- Email: [email protected]
Degradation of carbamazepine using hydrodynamic cavitation combined with advanced oxidation processes
Accepted Manuscript Degradation of Carbamazepine Using Hydrodynamic Cavitation Combined With Advanced Oxidation Processes Pooja Thanekar, Mihir Panda, Parag R. Gogate PII: DOI: Reference:
S1350-4177(17)30355-3 http://dx.doi.org/10.1016/j.ultsonch.2017.08.001 ULTSON 3806
To appear in:
Ultrasonics Sonochemistry
Received Date: Revised Date: Accepted Date:
8 May 2017 25 June 2017 1 August 2017
Please cite this article as: P. Thanekar, M. Panda, P.R. Gogate, Degradation of Carbamazepine Using Hydrodynamic Cavitation Combined With Advanced Oxidation Processes, Ultrasonics Sonochemistry (2017), doi: http:// dx.doi.org/10.1016/j.ultsonch.2017.08.001
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Degradation of Carbamazepine Using Hydrodynamic Cavitation Combined With Advanced Oxidation Processes
Pooja Thanekar, Mihir Panda, Parag R. Gogate*
Chemical Engineering Department, Institute of Chemical Technology, Matunga, Mumbai 40019, India
*Corresponding Author: E-mail: [email protected] Phone: +91 22 3361 2024 Fax: +91 22 3361 1020
Abstract Degradation of carbamazepine (CBZ), a widely detected recalcitrant pharmaceutical in sewage treatment plant (STP) effluent, has been studied in the present work using combination of hydrodynamic cavitation (HC) and advanced oxidation processes (AOPs). Due to its recalcitrant nature, it cannot be removed effectively by the conventional wastewater treatment plants (WWTPs) which make CBZ a pharmaceutical of very high environmental relevance and impact as well as stressing the need for developing new treatment schemes. In the present study, the effect of inlet pressure (3-5bar) and operating pH (3-11) on the extent of degradation have been initially studied with an objective of maximizing the degradation using HC alone. The established optimum conditions as pressure of 4 bar and pH of 4 resulted in maximum degradation of CBZ as 38.7%. The combined approaches of HC with ultraviolet irradiation (HC+UV), hydrogen peroxide (HC+H2O2), ozone (HC+O3) as well as combination of HC , H2O2 and O3 (HC+H2O2+O3) have been investigated under optimized pressure and operating pH. It was observed that a significant increase in the extent of degradation is obtained for the combined operations of HC+H2O2+O3, HC+O3, HC+H2O2, HC+ UV with the actual extent of degradation being 100%, 91.4%, 58.3% and 52.9% respectively. Kinetic analysis revealed that degradation of CBZ fitted first order kinetics for all the approaches. The processes were also compared on the basis of cavitational yield calculations and also in terms of total treatment cost. Overall, it has been demonstrated that combined process of HC, H2O2 and O3 can be effectively used for treatment of wastewater containing CBZ.
Keywords: Carbamazepine; Hydrodynamic cavitation; advanced oxidation processes; kinetic study; cavitational yield; total treatment cost.
1. Introduction: Carbamazepine (CBZ) is an antiepileptic drug commonly used for treatment of schizophrenia as well as bipolar disorder. Due the chronic administration in high dosages (100-2000 mg daily), the annual production is typically very high [1]. Approximately <3% of the dosed CBZ is excreted in unaltered form, along with the pharmacologically active 10, 11 epoxycarbamazepine and further hydrolyzed dihydroxy derivatives. As CBZ is highly stable, it allows long-term transportation within the aquatic environment [2]. Studies have demonstrated that the removal efficiency of CBZ by conventional wastewater treatment plants (WWTPs) is very low (<10%)[3], which results in presence of CBZ in bio-solids and treated water discharges. Considering these aspects, CBZ can get accumulated in root tissues of plants and also translocated into other parts including beans. CBZ has been reported to have significant on the embryonic cell growth [4]. The chromic exposure of fish to CBZ has been demonstrated to yield reduction in fish steroid hormone which influences the reproduction ability of fish population. Also, low concentration exposure of CBZ caused an adverse effect on histology of kidney and liver, hampering fish development [5]. Thus it becomes imperative to develop an efficient method which will ensure its complete removal from effluents. In literature, various advanced oxidation processes (AOPs) have been reported to be effective techniques for the degradation of complex emerging pollutants[6]. AOPs involves the production of highly oxidizing species (hydroxyl radicals, •OH) for the degradation and also complete mineralization of emerging pollutants. Among the AOPs, cavitation (acoustic and hydrodynamic), photo catalytic oxidation, Fenton (Fe2+/H2O2) and Fenton like processes have been applied with better efficacy for complete removal of organic pollutants[7,8]. Cavitation has shown considerable promise for wastewater treatment application over last few years[7] due to the significant effects in terms of local hot spots, highly reactive free radicals and
intense mixing based on turbulence and liquid circulation [9,10]. All these effects are extremely suitable for the oxidation of complex compounds, both organic as well as inorganic, including the pesticides and the emerging contaminants such as pharmaceutical drugs[11]. The two modes of cavitation generally found suitable for different chemical/physical transformations include acoustic and hydrodynamic cavitation [12]. In acoustic cavitation, high frequency sound waves (16 kHz–2 MHz) are utilized for the generation of cavities based on the variation of pressure in the liquid. Though most commonly applied at laboratory scale for degradation of various pollutants, ultrasonic reactors offer significant problems for large scale operation due to localized nature of intense cavitation zones, lower energy efficiency and higher treatment costs. Hydrodynamic cavitation (HC) reactors have been looked as an energy efficient alternative to ultrasonic reactors [13,14]. In the case of hydrodynamic cavitation, presence of constriction in the liquid flow drives the different stages of cavitation [7] based on the changes in the kinetic energy of the liquid and the local pressure. At the downstream of the constriction, a very high intensity fluid turbulence occurs and generation of oxidants occurs attributed to the violent collapse of the cavities [13]. Various studies have been reported on the degradation of CBZ using AOPs such as photocatalysis[15,16] and Fenton’s reaction[17] operated individually as well as using combined treatment schemes such as sonoelectrochemical oxidation[18], sonophoto catalytic degradation[19],
Hydrodynamic
acoustic
cavitation
(HAC)
[20]
and
combined
Hydrodynamic cavitation- hydrogen peroxide (HC/H2O2) [21] approach. Zupanc et al. [21] investigated the removal efficiencies of five model pharmaceuticals as ibuprofen, naproxen, ketoprofen, carbamazepine and diclofenac using different approaches based on biological processes, HC and UV treatment. The removal extent of CBZ using the combined approach of HC/H2O2 was reported to be around 80% within 30 min under the
optimized parameters of 20ml of 30% H2O2 and initial pressure of 6 bar. The combined operation of three processes i.e. biological process, HC and UV treatment under optimized conditions resulted in maximum removal extent as >98%. Braeutigam et al. [20] investigated a novel approach of Hydrodynamic-Acoustic-Cavitation (HAC) for the degradation of CBZ and reported that 96% degradation was obtained within 15 min under optimized conditions. The observed synergistic effect was 63% as compared to the addition of individual approaches. Exposito et al. [19] studied photo-Fenton degradation of CBZ combined with ultrasound (US/UV/H2O2/Fe) and reported around 60 % of mineralization. Tran et al. [18] reported synergistic effects of ultrasound in the sonoelectrochemical oxidation for degradation of CBZ. The degree of synergy was reported to be strongly dependent on the current intensity. Dong et al. [22] studied degradation of CBZ using direct and sensitized photolysis. The sensitized photolysis on five days exposure resulted in degradation in the range of 67–98%. Ghauch et al. [23] investigated CBZ oxidation using an improved Fenton’s process based on combination of ultrasound, zero valent iron and hydrogen peroxide. It was reported that almost 90% degradation of CBZ was obtained using optimized loading of Fe0 acting as pseudo catalyst combined with low ultrasound (US) frequency (40 kHz) and H2O2. Deng et al. [24] investigated CBZ degradation using UV irradiation in the presence of oxidants such as hydrogen peroxide (H2O2), peroxymonosulfate (PMS), and persulfate (PS). Higher extent of degradation was observed in the presence of oxidant PS as compared to H2O2 and PMS. Detailed analysis of literature revealed that many studied are available reporting the use of AOP for degradation of CBZ, but no studies have been reported based on combination of HC with other AOPs such as H2O2, Ozone and UV treatment. Considering this analysis, the present work focuses on developing an efficient combined oxidation approach based on HC which can lead to significant efficacy for degradation, which can prompt possible commercial
applications. The work also compares the effectiveness of processes such as HC/H2O2, HC/ozone, and HC/UV in terms of cavitational yield and the treatment costs. 2. Materials and Methodology: 2.1 Materials Carbamazepine was obtained from High Media Pvt. Ltd., Mumbai, India. Hydrogen peroxide (30%, w/v) of AR grade and Acetonitrile of HPLC grade were obtained from Thomas Baker Pvt. Ltd., Mumbai, India. The freshly prepared distilled water, using the laboratory distillation unit obtained from Borosil Glass Work Ltd., Mumbai, India was used for preparation of solutions of known concentrations. 2.2 Experimental set up The schematic representation of experimental setup of HC used in the present work has been depicted in Fig.1. The setup consists of a closed loop circuit including a feed tank, a reciprocating pump of power rating 1.1 kW, pressure gauges, flanges to accommodate the cavitating device (slit venturi) and control valves to control the flow rate through the main and bypass lines. The setup also includes a main line housing the slit venturi and a bypass line to control the flow rate through the main line. The geometric details of slit venturi used as cavitating device in the preset work have been reported by Patil et al. [25]. For the combined approach of HC and UV, two UV lamps (Philips TUV 4 W/G4T5) of output power 8 W each with a dominant wavelength of 254 nm were inserted inside the feed tank of HC reactor. For combined approach of HC and H2O2, different ratios of CBZ: H2O2 as 1:1(10 mg/L H2O2), 1:2 (20 mg/L H2O2), 1:3(30 mg/L H2O2), 1:4(40 mg/L H2O2), 1:5(50 mg/L H2O2), and 1:6(60 mg/L H2O2) have been used. Ozone generator (model-DOZ400) procured from Eltech Engineering, Mumbai has been used for combined approach of HC and ozone. Ozone gas was introduced into the feed tank at the required flow rate using a ceramic diffuser.
2.3
Methodology
For all the degradation experiments, 4L aqueous solution of 10ppm CBZ was taken in the feed tank. After starting the circulation pump, the pressure at the inlet was adjusted by closing the by-pass line. Different inlet pressures over the range of 3 to 5 bar have been used in the study. The constant feed temperature of 35°C was achieved based on the circulation of cooling water through the jacket. To study the effect of pH on the extent of degradation, different pH values ranging from 3-11 were varied in the study with adjustments based on the use of 0.1 M H2SO4 and 0.1 M NaOH as required. All the experimental runs were performed for a treatment time of 120 min and samples were removed at regular time interval of 20 min for the analysis of extent of degradation. Experiments related to the combination of HC and AOPs were then performed under optimum inlet pressure and pH. In order to study efficacy of combined operation of HC/UV process on extent of degradation, UV lamp of 8W and 16 W placed inside a jacketed quartz cylinder was inserted vertically inside the feed tank of HC reactor. The effect of addition of hydrogen peroxide (H2O2) on the degradation of CBZ in presence of HC has also been studied at different loadings of H2O2 using the ratios of CBZ: H2O2 from 1:1 to 1:6 for the fixed initial concentration of CBZ (10ppm). The combined effect of HC/ozone on extent of degradation of CBZ has been studied by injecting ozone inside the feed tank of HC reactor at flow rate of 400 mg/h. 2.4 Analysis CBZ concentration was monitored using the Agilent High Performance Liquid Chromatography (HPLC) unit with an Agilent eclipse plus C-18 column having dimensions of 4.6×100 mm and particle size of 3.5 µm. The mobile phase of acetonitrile: water (40:60) with the flow rate of 1mL/min was used in the work. The eluted CBZ was detected at wavelength of 220 nm using UV detector. Integral method of analysis was used for fitting the kinetic model to the degradation process. The treatment cost was also calculated to compare
the efficacy of the combination approaches with the individual treatment approaches. The intermediates formed during the degradation of CBZ were identified using liquid chromatography–mass spectroscopy (LC- MS) technique. 3. Results and Discussion 3.1 Effect of inlet pressure The studies related to understanding the effect of inlet pressure were performed at natural pH of solution (11.6). The obtained results for the effect of inlet pressure on extent of degradation of CBZ over the range of 3 -5 bar has been depicted in Fig.2 (a). The integral analysis was also performed to find the kinetic rate constants and reaction order. Fig.2 (b) shows the plot of ln (Ca0/Ca) vs. time for the first order kinetics and the obtained results for the kinetic rate constant are given in Table 1. It was observed that at 4 bar inlet pressure, maximum extent of degradation obtained was 16.5% with first order rate constant of 1.1×10 -3 min-1 using HC reactor with slit venturi as cavitating device. Typically, the optimum value of pressure is in the range of 4-6 bar for low pressure configurations such as orifice plate and venturi [26]. From Fig. 2(a), it can be observed that the extent of degradation increases with an increase in the inlet pressure up to 4 bar and any further increase beyond this results in only marginal decrease in the extent of degradation. The cavitational intensity increases with an increase in pressure based on a lower cavitation number. However, further increase in pressure beyond optimum value leads to the formation of cavity cloud which in turn reduces cavitational intensity resulting in a decrease in the extent of degradation [27,28]. Saharan et al. [29] have confirmed the cavity cloud formation inside a transparent venturi by performing photographic study at different inlet pressures. Wang and Zhang [30] studied the alachlor herbicide degradation using HC and also reported the increase in degradation rate with an increase in inlet pressure from 0.2 MPa to 0.6 MPa. Chakinala et al. [31] studied the treatment of real industrial effluent using combined operation of HC and heterogeneous
advanced Fenton process (AFP) in presence of zero valent iron as the catalyst. It was reported that 60% TOC removal is obtained at 1500psi (10,340kPa), whereas at low pressure such as 1000psi (6893.3kPa) and 500psi (3446.7kPa) the extent of TOC removal was only about 52% and 50% respectively. Bagal and Gogate [32] have also reported similar effect of pressure on extent of degradation of pharmaceutical drug, diclofenac sodium. For 20 ppm aqueous solution of diclofenac sodium, maximum degradation is at 3 bar pressure was 20.81% using venturi as cavitating device. Jadhav et al. [33] investigated the synergistic effect of HC and H2O2 on degradation of imidacloprid. The extent of degradation has been investigated at different inlet pressures (5-20 bar) using circular venturi as a cavitating device. It was reported that the rate of degradation of imidacloprid increased with an increase in pressure till an optimum pressure of 15 bar. The comparison of the extents of degradation obtained for different pollutants at varying pressure reveals that though the trend is similar, the optimum value of pressure is different and also the extent of intensification obtained at varying pressures is different. This analysis confirms the necessity of performing the detailed investigation related to effect of inlet pressure and hence establishes the importance of the current work. 3.2Effect of pH The experiments for understanding the effect of pH on the extent of degradation were performed at varying pH over the range from 3-11, at optimized 4 bar inlet pressure. The obtained results for the extent of degradation and kinetic rate constant have been shown in the Fig. 3 and Table 2. It was observed that minimum degradation was obtained as 19.0% at pH 11, whereas maximum degradation of 38.7 % was achieved at pH 4. It is also interesting to observe that the rate of degradation is higher in the initial stages and lowers after about 60 min of operation which is a typical first order behavior and also some contribution from the dissolved gases in the initial period drives such trend. The trend is significantly seen for pH
of 4 where maximum degradation is observed. The first order kinetic rate constant was also observed to decrease as pH increases. Under the acidic conditions, generation of OH radical is favored as its oxidation potential is higher. Remaining experiments were performed keeping pH of solution constant at 4. Deng et al. [24] have also reported that maximum degradation occurred at low pH. Patil and Gogate [28] reported that the degradation of methyl parathion using hydrodynamic cavitation was higher at acidic condition ( pH as 3) than alkaline pH (pH as 8.2). Pradhan and Gogate [34] also reported that maximum degradation of p-nitrophenol was obtained as 63.2% using combination of HC and Fenton chemistry at pH 3.75, whereas at pH 8 (alkaline condition), considerably lower removal (35.7 %) was obtained. Ghauch et al. [23] also observed significant removal of CBZ at pH 3 (95%) with lower removal at pH 5 (60%) using ultrasonic/Fe0/H2O2 systems. Rajoriya et al. [35] studied the decolorization of Rhodamine 6G dye using HC coupled with other oxidative agents such as H2O2 and ozone. It was reported that the decolorization rate was higher in basic conditions (optimum value of 10.0) than acidic conditions (pH of 2). The maximum extent of degradation of 32.1% was obtained at optimized pH of 10 with kinetic rate constant of 3×10-3min-1. The comparison of the observed trends in different literature illustrations revealed that exact optimum pH and the extent of variation in the degradation obtained is different and hence effect of pH was studied in details for CBZ. 3.3 Combined operation of HC/UV: In order to study the efficacy of combined operation of HC and UV, degradation of CBZ was studied by inserting UV lamp (8W and 16W) inside the feed tank. The obtained results for the combination approach have been given in Fig. 4. It can be observed that the maximum extent of degradation (52.9%) was obtained using UV lamp of power 16W and lower extent of degradation was obtained at 8W power of UV (45.4%). Using only HC resulted in an extent of degradation as 38.7% under otherwise similar conditions. Thus it can be said that
use of UV in combination with HC helps in increasing the extent of degradation by about 15 to 40% depending on the rated power as compared to only HC (considered as base value for calculations of percentage increase). The degradation of CBZ using combined approach also followed first order kinetics and rate constant obtained for combination with 16W UV lamp was 4.9×10-3 min-1. In order to compare individual approach of UV with combined treatment of HC+UV, set of experiments were performed by closing main line valve of HC setup so that the solution bypasses the cavitating device and is only exposed to UV irradiation. The observed extent of degradation using only 16W UV lamp was 18% whereas earlier studies established that degradation obtained using only HC was 38.7%. It was thus established that the combined operation gives higher extents of degradation. UV irradiation generates OH radicals via photolysis of water molecule, whereas in HC, collapse of cavities yields OH radicals. Hence, combined operation of HC/UV leads to generation of more OH radicals than HC alone or UV alone which results in an increase in the extent of degradation[32]. The synergistic index based on degradation rate constant can be calculated by the following Eq. (1)
=
=
. × .× . ×
= 0.9
(1)
The obtained synergistic index revealed that the combined method of HC+UV results in better efficiency that individual method but no synergism was observed. Deng et al. [24] investigated CBZ degradation using UV (253.7 nm) irradiation in combination with oxidants like hydrogen peroxide (H2O2), peroxymonosulfate (PMS) and persulfate (PS). It was reported that maximum degradation efficiency was obtained using the UV/PS combination followed by UV/H2O2 and minimum for the UV/PMS combination. Pereira et al. [36] investigated UV photolysis and UV/H2O2 oxidation of pharmaceutically active compounds including ketoprofen, naproxen, carbamazepine, ciprofloxacin, clofibric acid, and iohexol. It was reported that negligible removal of CBZ was observed when
subjected to only UV irradiation at intensity of 100mJ/cm2. However enhanced removal of CBZ up to 13% was observed when 10mg/L of hydrogen peroxide was added in sample before its exposure to UV irradiation, confirming the role of hydrogen peroxide in enhancing the free radical formation. Zupanc et al. [21] reported that use of hydrodynamic cavitation with photolysis resulted in beneficial results for the degradation of CBZ along with other pharmaceutical compounds including diclofenac, ibuprofen, naproxen, ketoprofen and active metabolite of the lipid regulating agent clofibric acid. Barik and Gogate [37,38] studied the extent of degradation of 4-chloro 2-aminophenol using combined process of US as well as HC with AOPs such as photolysis and ozone. In the case of US coupled with UV, the extent of degradation found was more (88.42%) than the individual processes of US (24.17%) and UV (80.8%). Also in case of HC combined with UV and O3, maximum extent of degradation obtained was 96.85% with TOC reduction of 73.6%. 3.4 Combined operation of HC and hydrogen peroxide (H2O2) Approach of hydrogen peroxide in combination with HC was also investigated and observed results have been depicted in Fig. 5. The effect of different loadings of H2O2 using the ratios of CBZ: H2O2 as 1:1, 1:2, 1:3, 1:4,1:5 and 1:6 was investigated. It was observed that the extent of degradation increases from 31% to 58.3% as loading of H2O2 increases from 1:1 to 1:5. Also the reaction fitted to first order kinetics and rate constant observed at 1:5 H2O2 loading was the maximum as 6.1×10 -3min-1. Further increase in H2O2 loading to 1:6 resulted in a decrease in the extent of degradation. The lower degradation at highest loading is attributed to scavenging action of residual H2O2. Beyond the optimum loading of H2O2, generated OH radicals react with H2O2 as given by following reaction(2) [39]. .
H2O2 +OH
H2O+ HO2
(2)
This phenomenon of scavenging is also confirmed from the literature reports though different optimum values of H2O2 loading are observed. Mishra and Gogate[40] investigated the
application of combined approach of HC and H2O2 on degradation of Rhodamine B by taking five different concentrations of H2O2, ranging from 10mg/L to 200mg/L. It was reported that degradation of Rhodamine B increased up to 99.9% in the presence of 200 mg/L H2O2 with TOC reduction of 55%. Also, the combined effect of HC and H2O2 was studied by Jadhav et al. [33] for the degradation of imidacloprid insecticide and 100% degradation was reported in 45 min of operation at molar ratio of imidacloprid : H2O2 as1:40. . In the present work, the extent of degradation of CBZ and rate constant obtained using only H2O2 (1:5 ratio) was 29.4 and 2.2×10-3 min-1 respectively. The operation of using only hydrogen peroxide induced degradation was again based on closing main line valve of HC setup blocking the flow though cavitating device. To compare efficiency of hybrid processes (HC+ H2O2) with individual process, synergistic index was again calculated as per the following Eq. (3):
=
=
.× .× . ×
= 1.01
(3)
The obtained synergistic index confirmed that the combined method is better than the individual method and also gives more than the additive effect. The observed trend is attributed to enhanced generation of OH* radicals by increasing the rate of dissociation of H2O2 in presence of HC. Also, HC generates turbulence which increases diffusivity leading to elimination of mass transfer resistances for the pollutant [33]. Zupanc et al. [21] have also reported beneficial results for the combination of hydrodynamic cavitation and hydrogen peroxide with much higher degradation as 89% under optimum dosage of hydrogen peroxide as 20 mL as compared to only 24% degradation for the operation of only hydrodynamic cavitation. 3.5 Combined operation of HC and Ozone Ozone is a strong oxidant with standard reduction potential (E0) of 2.07 V and can be effectively used for degradation of complex compounds such as pesticides, dyes,
pharmaceuticals etc. [41]. The reaction of ozone with pollutants follows two types of mechanism viz. direct molecular attack and indirect reaction involving OH radicals [42]. Ozone coupled with HC can result in more degradation rates as compared to HC alone and ozone alone, which is attributed to elimination of mass transfer resistance due to cavitational effects along with formation of highly reactive OH radicals [43,44]. In this study, ozone loading of 400 mg/h was injected directly inside the feed tank containing CBZ solution, using ozone generator for 120 min of treatment. From the results depicted in Fig.6, it can be observed that the extent of degradation and rate constant obtained was 91.3% and 19.1×10 -3 min-1 respectively under optimized conditions. In order to obtain extent of degradation and rate constant of CBZ using only ozone, the main line valve of HC setup was closed so that all the flow goes through bypass line and ozone loading of 400 mg/h was injected inside the tank. The extent of degradation and rate constant obtained using only ozone was 49.1% and 4.8×10 -3 min-1 respectively. To compare efficiency of combined process of HC and Ozone with individual process, synergistic index was calculated using following Eq. (4)
=
!
=
.× .× .×
= 2.2
(4)
The obtained synergistic index demonstrates that the combined effect is more efficient over the individual method. The cavitation generates turbulence which overcomes mass transfer limitations and also results in decomposition of ozone into reactive species like nascent oxygen and OH* radicals which in turn increases extent of degradation. The combined mechanism of elimination of mass transfer resistance (dominant in the present case due to the gas liquid nature of system as compared to other combinations involving hydrogen peroxide or UV light) and production of additional oxidants gives the maximum synergistic effect for the current combination. Barik and Gogate [45] have reported similar increase in the extent of degradation of 2,4dichlorophenol using combination of US/Ozone/Catalyst. Gogate and Patil [43] studied the
degradation of triazophos using the combined process of HC and O3. It was reported that introducing ozone in the feed tank gave about 86.68% degradation, whereas 49.67% and 59.36% degradation was obtained using individual approach of HC and O3 alone respectively. Patil and Gogate [44] reported complete degradation of dichlorvos pesticide with 93% removal of TOC in 30 min of treatment using the combined operation of ozone (1.95 g/h) and sonication. Similarly, effect of combination of HC and ozone on degradation of Rhodamine 6G dye was studied by Rajoriya et al. [35]. It was reported that 100% decolorization observed in 10 min at ozone feed rate of 3 g/h. TOC reduction of 73.19% with rate constant 10.9×10 -3min-1 was also reported in 120 min of reaction time at ozone feed rate of 3 g/h. 3.6 Combined operation of HC+H2O2+O3 The combination of HC, H2O2 (CBZ: H2O2 =1:5) and O3 (flow rate= 400mg/h) was also investigated in the work and observed to give complete degradation of CBZ within 100 min of treatment as per the results represented in Fig. 7. To compare individual approaches with combined treatment, set of experiments were performed by closing main line valve of HC set up so that all the flow gores through the by-pass line allowing restriction to flow passage through cavitation chamber. By this method, the extent of degradation for the individual treatments such as UV, H2O2 and O3 were obtained. From Fig.8, it can be observed that extent of degradation of combined treatment approaches such as HC+UV, HC+H2O2, HC+O3, HC+H2O2+O3 was higher as compared to the individual approach of HC, UV, H2O2 and O3. This is attributed to generation of more OH radicals as well as enhancement in the mass transfer due to cavitation [43]. The obtained values for the synergistic Index are given in Table 5 whereas calculation for combined HC+H2O2+O3 is shown as follows:
=
!
=
.#× .× . × .×
= 3.2
(5)
The observed synergistic index for combined operation of HC+H2O2+O3 was higher as compared to other approaches which may be attributed to generation of more OH radicals in combined operations than individual operation and also stronger contribution of the mass transfer elimination.
3.7 Analysis of intermediates: Intermediate analysis was performed for the combined approach of HC with H2O2 and O3 where maximum extent of degradation (100%) was achieved. Intermediates were analyzed using LC-MS technique. The prominent peaks were observed at m/z 141.04, 183.08, 166.02, 296.13 and 187.16 in the mass spectra. The compounds detected based on free radical oxidation of CBZ were 2-Aminomuconate 6-semialdehyde (A), Benzoquinone acetic acid (B), Racepinephrine (C), Di-demethylcitalopram (D), N1-Acetylspermidine (E) ,swietenine (F) as depicted in Fig. 9. 3.8 Cavitational yield and cost of treatment: Cavitational yield is defined as desired chemical change obtained per unit power dissipation. In hydrodynamic cavitational reactors, the energy delivered by the reciprocating pump is main energy dissipation source for generating cavitation [14]. The power dissipation per unit volume was obtained to be 5.87 W/L based on flow rate basis (Power= flow rate ×pressure). From the results given in Table 4, the cavitational yield (detailed calculation has been given in appendix I) for HC+H2O2+O3 was observed to be higher (15.7×10-5mg/J) as compared to other processes. Patil and Gogate [28,44] have obtained cavitational yield of 4.44×10
-6
mg/J
for the 44 % of extent of degradation for the 20 ppm initial solution of methyl parathion, whereas 8.08 × 10 −5 mg/J of cavitational yield was obtained for degradation of dichlorvos pesticide using combined effect of US + solar + TiO2. The operating cost of the treatment was also calculated from the cavitational yield given in
Table 4. It was observed that the treatment cost requirement for combined process of HC+H2O2+O3 is 0.16 Rs/L which is quite low as compared to other treatment methods. The operation of HC alone would cost around 0.27 Rs/L which is higher as compared to other combined approaches based on HC. Therefore to obtain better cost efficiency, the combined process is preferable. Patil and Gogate[44] reported cost estimation for degradation of dichlorvos using combined ultrasound coupled with AOPs and also observed that higher cost was required for individual operation related to use of ultrasound (5.69 Rs/L), H2O2 (6.37 Rs/L), and TiO2 (4.16 Rs/L) as compared to the combined processes.
4 .Conclusions: The present work demonstrated the effective use of HC coupled with AOPs such as UV irradiation, H2O2 and O3 for degradation of CBZ. The use of HC alone for degradation of CBZ resulted in 38.7% degradation, whereas combination of HC+H2O2+O3 resulted in almost complete degradation within 100 min at optimized loadings. It has been conclusively established combined treatment approaches such as HC+UV, HC+H2O2, HC+O3, HC+H2O2+O3 resulted in showing enhanced reaction rates as compared to the individual approach of HC, UV, H2O2 and O3. The combination of HC+H2O2+O3 resulted in 100 % degradation of CBZ in 100 min of treatment with operating cost of 0.16 Rs/L. The calculated synergistic index confirmed the effectiveness of combined approaches as compared to the individual approaches. Also, it has been observed that the use of hydrodynamic cavitation alone may not give satisfactory results of extent of degradation of target compound and hence it is recommended to use HC coupled with other appropriate AOPs. Overall it can be concluded that using optimized combination of HC with ozone and hydrogen peroxide is the best treatment approach for the complete degradation of CBZ in most economic manner.
Appendix-I Sample calculation for Cavitational yield: (mg/J) Power dissipated for 4 L reaction volume (W) = Flow rate (m3/s) × ∆P (N/m2) = 78.12×10 -6×3×105 = 23.43 Power rating of pump (based on flow rate basis) =23.43 W Power dissipated per unit volume= 23.43/4 = 5.87 W/L Extent of degradation= Cavitational yield=
×.#
= 3.87mg/L
+,-./- 01 2.34525-60/ 708.4 26996:5-60/
=
.# ;.#× ×
= 9.15×10-5 mg/J
Sample calculation for Cost of treatment: Cavitational yield = 9.15×10-5 mg/J Energy required for removal of CBZ = 10/9.15×10-5 = 0.03035 kWh Considering 1 kWh = Rs. 8.78 (Maharashtra State Electricity Distribution Co. Ltd., 2012) Cost of treatment = 0.030 × 8.78 = 0.27Rs.
Acknowledgement: Authors would like to acknowledge the funding of Department of Science and Technology under the Water Technology initiative scheme (Project reference: DST/TM/WTI/2K15/126(G)). Authors would also like to acknowledge the funding of TEQIP INN scheme for fellowship to Mihir Panda
5. References [1]
T. Kosjek, H.R. Andersen, B. Kompare, A. Ledin, Fate of Carbamazepine during Water Treatment, Environ. Sci. Technol. 43 (2009) 6256–6261.
[2]
S.M. C.Tixier, H. Singer, S. oellers , S.R. Muller,Occurrence and Fate of Occurrence
and Fate of Carbamazepine, Clofibric Acid, Diclofenac, Ibuprofen, Ketoprofen, and Naproxen in Surface Waters, Environ. Sci. Technol. 37 (2003) 1061–1068. [3]
Y. Zhang, S. Geiben, C. Gal, Chemosphere Carbamazepine and diclofenac : Removal in wastewater treatment plants and occurrence in water bodies, Chemosphere. 73 (2008) 1151–1161.
[4]
S. Castiglioni, E. Zuccato, R. Fanelli, D. Vigetti, C. Rossetti, D. Calamari, Effects of a Complex Mixture of Therapeutic Drugs at Environmental Levels on Human Embryonic Cells, Environ. Sci. Technol. 40 (2006) 2442–2447.
[5]
M. Galus, N. Kirischian, S. Higgins, J. Purdy, J. Chow, S. Rangaranjan, H. Li, C. Metcalfe, J.Y. Wilson, Chronic , low concentration exposure to pharmaceuticals impacts multiple organ systems in zebrafish, Aquat. Toxicol. 132–133 (2013) 200– 211.
[6] I. Michael, Z. Frontistis, D. Fatta-kassinos, Removal of Pharmaceuticals from Environmentally Relevant Matrices by Advanced Oxidation Processes ( AOPs ), Chapter in book by M. Petrovic, S. Perez, D. Barcelo (Eds), Analysis, Removal, Effects and Risk of Pharmaceuticals in the Water cycle 2nd ed., Elsevier U.K.(2013) 345-408 [7]
P.R. Gogate, Cavitational reactors for process intensification of chemical processing applications: A critical review, Chem. Eng. Process. Process Intensif. 47 (2008) 515– 527.
[8]
H. Wang, W. Liang, Q. Zhang, W. Jiang, Solar-light-assisted Fenton oxidation of 2,4dinitrophenol (DNP) using Al2O3 -supported Fe ( III ) -5-sulfosalicylic acid (ssal) complex as catalyst, Chem. Eng. J. 164 (2010) 115–120.
[9]
T.G. Leighton, Bubble population phenomena in acoustic cavitation,Ultrason. Sonochem. 2 (1995) 123–136.
[10] P. Cintas, J. Luche, Green chemistry: The sonochemical approach, Green Chem. 43 (1999) 115–125. [11] P.R. Gogate, A.B. Pandit, Application of Cavitational reactors for cell disruption for recovery of intracellular enzymes, J.Chem.Technol.Biotechnol.1093 (2008) 1083– 1093. [12] P.R. Gogate, A.M. Kabadi, Authors personal copy A review of applications of cavitationin biochemical engineering / biotechnology, Biochem. J. 44 (2009) 60–72 [13] P.R. Gogate, A.B. Pandit, A review and assessment of hydrodynamic cavitation as a technology for the future, Ultrason. Sonochem. 12 (2005) 21–27. [14] P.R. Gogate, I.Z. Shirgaonkar, M. Sivakumar, P. Senthilkumar, N.P. Vichare, A.B. Pandit, Cavitation reactors: Efficiency assessment using a model reaction, AICHE J. 47 (2001). [15] M.W. Lam, S.A. Mabury, Photodegradation of the pharmaceuticals atorvastatin, carbamazepine, levofloxacin, and sulfamethoxazole in natural waters, Aquat. Sci. 67 (2005) 177–188. [16] S.Chiron, C. Minero, D. Vione, Photodegradation Processes of the Antiepileptic Drug Carbamazepine, Relevant To Estuarine Waters, Environ. Sci. Technol. 40 (2006) 5977–5983. [17] A. Karpinska, A. Sokol, J. Karpinska, Studies on the kinetics of carbamazepine degradation in aqueous matrix in the course of modified Fenton’s reactions, J. Pharm.
Biomed. Anal. 106 (2015) 46–51. [18] N. Tran, P. Drogui, S. Brar, A. Coninck, Synergistic effects of ultrasounds in the sonoelectrochemical oxidation of pharmaceutical carbamazepine pollutant, Ultrason. Sonochem. 34 (2017) 380–388. [19] A.J. Exposito, D.A. Patterson, J.M. Monteagudo, A. Duran, Sono-photo-degradation of carbamazepine in a thin falling film reactor: Operation costs in pilot plant, Ultrason. Sonochem. 34 (2017) 496–503. [20] P. Braeutigam, M. Franke, R.J. Schneider, A. Lehmann, A. Stolle, B. Ondruschka, Degradation of carbamazepine in environmentally relevant concentrations in water by Hydrodynamic-Acoustic- Cavitation ( HAC ), Water Res. 46 (2012) 2469–2477. [21] M. Zupanc, T. Kosjek, M. Petkovsek, M. Dular, B. Kompare, B. Sirok, Z. Blazeka, E. Heath, Removal of pharmaceuticals from wastewater by biological processes, hydrodynamic cavitation and UV treatment, Ultrason. Sonochem. 20 (2013) 1104– 1112. [22] M.M. Dong, R. Trenholm, F.L. Rosario-Ortiz, Photochemical degradation of atenolol, carbamazepine, meprobamate, phenytoin and primidone in wastewater effluents, J. Hazard. Mater. 282 (2015) 216–223. [23] A. Ghauch, H. Baydoun, P. Dermesropian, Degradation of aqueous carbamazepine in ultrasonic/Fe0/H2O2 systems, Chem. Eng. J. 172 (2011) 18–27. [24] J. Deng, Y. Shao, N. Gao, S. Xia, C. Tan, S. Zhou, X. Hu, Degradation of the antiepileptic drug carbamazepine upon different UV-based advanced oxidation processes in water, Chem. Eng. J. 222 (2013) 150–158.
[25]
P.N. Patil, S.D. Bote, P.R. Gogate, Degradation of imidacloprid using combined advanced oxidation processes based on hydrodynamic cavitation, Ultrason. Sonochem. 21 (2014) 1770–1777.
[26] P.R. Gogate, P.N. Patil, Combined treatment technology based on synergism between hydrodynamic cavitation and advanced oxidation processes, Ultrason. Sonochem. 25 (2015) 60–69. [27] M. V. Bagal, P.R. Gogate, Degradation of 2,4-dinitrophenol using a combination of hydrodynamic cavitation, chemical and advanced oxidation processes, Ultrason. Sonochem. 20 (2013) 1226–1235. [28] P.N. Patil, P.R. Gogate, Degradation of methyl parathion using hydrodynamic cavitation: Effect of operating parameters and intensification using additives, Sep. Purif. Technol. 95 (2012) 172–179. [29] V.K. Saharan, M.P. Badve, A.B. Pandit, Degradation of Reactive Red 120 dye using hydrodynamic cavitation, Chem. Eng. J. 178 (2011) 100–107. [30] X. Wang, Y. Zhang, Degradation of alachlor in aqueous solution by using hydrodynamic cavitation, J. Hazard. Mater. 161 (2009) 202–207. [31] A.G. Chakinala, P.R. Gogate, A.E. Burgess, D.H. Bremner, Industrial wastewater treatment using hydrodynamic cavitation and heterogeneous advanced Fenton processing, Chem. Eng. J. 152 (2009) 498–502. [32] M. V. Bagal, P.R. Gogate, Degradation of diclofenac sodium using combined processes based on hydrodynamic cavitation and heterogeneous photocatalysis, Ultrason. Sonochem. 21 (2014) 1035–1043.
[33] S. Raut-jadhav, V. Kumar, D. Pinjari, S. Sonawane, D. Saini, A. Pandit, Synergetic effect of combination of AOP ’ s ( hydrodynamic cavitation and H2O2) on the degradation of neonicotinoid class of insecticide, J. Hazard. Mater. 261 (2013) 139– 147. [34] A.A. Pradhan, P.R. Gogate, Removal of p-nitrophenol using hydrodynamic cavitation and Fenton chemistry at pilot scale operation, Chem. Eng. J. 156 (2010) 77–82. [35] S. Rajoriya, S. Bargole, V.K. Saharan, Degradation of a cationic dye (Rhodamine 6G) using hydrodynamic cavitation coupled with other oxidative agents: Reaction mechanism and pathway, Ultrason. Sonochem. 34 (2017) 183–194. [36] V.J. Pereira, K.G. Linden, H.S. Weinberg, Evaluation of UV irradiation for photolytic and oxidative degradation of pharmaceutical compounds in water, Water Res. 41 (2007) 4413–4423. [37] A.J. Barik, P.R. Gogate, Degradation of 4-chloro 2-aminophenol using combined strategies based on ultrasound, photolysis and ozone, Ultrason. Sonochem. 28 (2016) 90–99. [38] A.J. Barik, P.R. Gogate, Degradation of 4-chloro 2-aminophenol using a novel combined process based on hydrodynamic cavitation, UV photolysis and ozone, Ultrason. Sonochem. 30 (2016) 70–78. [39] A.L. Patil, P.N. Patil, P.R. Gogate, Degradation of imidacloprid containing wastewaters using ultrasound based treatment strategies, Ultrason. Sonochem. 21 (2014) 1778–1786. [40] K.P. Mishra, P.R. Gogate, Intensification of degradation of Rhodamine B using hydrodynamic cavitation in the presence of additives, Sep. Purif. Technol. 75 (2010)
385–391. [41] K. Chandrasekara Pillai, T.O. Kwon, I.S. Moon, Degradation of wastewater from terephthalic acid manufacturing process by ozonation catalyzed with Fe2+, H2O2 and UV light: Direct versus indirect ozonation reactions, Appl. Catal. B: Environ. 91 (2009) 319–328. [42] R.K. Joshi, P.R. Gogate, Degradation of dichlorvos using hydrodynamic cavitation based treatment strategies, Ultrason. Sonochem. 19 (2012) 532–539. [43] P.R. Gogate, P.N. Patil, Combined treatment technology based on synergism between hydrodynamic cavitation and advanced oxidation processes, Ultrason. Sonochem. 25 (2015) 60–69. [44] P.N. Patil, P.R. Gogate, Degradation of dichlorvos using hybrid advanced oxidation processes based on ultrasound, J. Water Process Eng. 8 (2015) 58–65. [45] A.J. Barik, P.R. Gogate, Degradation of 2,4-dichlorophenol using combined approach based on ultrasound, ozone and catalyst, Ultrason. Sonochem. (2016).
List of Figures: Figure 1 Schematic representation of HC reactor Figure 2 (a) Effect of inlet pressure on extent of degradation of CBZ Figure 2 (b) Kinetic data fitting for the degradation of CBZ at different operating pressure Figure 3 Effect of pH on extent on degradation of CBZ Figure 4 Degradation of CBZ using combined approach of HC and UV radiation Figure 5 Degradation of CBZ using combined approach of HC and H2O2 loading Figure 6 Degradation of CBZ using combined approach of HC and ozone Figure 7 Degradation of CBZ using combined approach of HC+H2O2+ O3 Figure 8 Comparison of different approaches in terms of extent of degradation of CBZ Figure 9 Analysis of intermediates using LC-MS List of Tables: Table 1: Effect of inlet pressure on extent of degradation of CBZ and kinetic rate constant Table 2: Effect of pH on extent of degradation of CBZ and kinetic rate constant Table 3: Comparison of different combined processes in terms of synergistic index Table 4: Comparison of cavitational yield and total treatment cost
Figure 1 Schematic representation of HC reactor
18
P= 3 bar
P= 4 Bar
P= 5 Bar
Extent of Degradation (%)
16 14 12 10 8 6 4 2 0 0
20
40
60
80
100
120
Time (min)
Figure 2 (a) Effect of pressure on extent of degradation of CBZ
P= 3 bar
P= 4 bar
P= 5 bar
0.2 y = 0.0014x R² = 0.9679
0.18 0.16
ln Ca0/Ca
0.14
y = 0.0011x R² = 0.8424
0.12 0.1 0.08
y = 0.0006x R² = 0.897
0.06 0.04 0.02 0 0
20
40
60
80
100
120
Time (min)
Figure 2 (b) Kinetic data fitting for the degradation of CBZ at different operating pressure
Extent of Degradation (%)
50
pH = 3
pH = 4
pH = 5
pH = 6
20
40
60
80
pH=11
40
30
20
10
0 0
100
120
Time (min)
Figure 3 Effect of pH on extent of degradation of CBZ
60
Extent of Degradation (%)
8 Watt
16 Watt
50
40
30
20
10
0 0
20
40
60
80
100
120
Time (min)
Figure 4 Combined effect of HC and UV radiation on extent of degradation of CBZ
70
H2O2 (1:3) H2O2 (1:2) H2O2 (1:6)
Extent of degradation (%)
60
H2O2 (1:4) H2O2 (1:1) H2O2 (1:5)
50 40 30 20 10 0 0
20
40
60
80
100
120
Time (min)
Figure 5 Combined effect of HC and H2O2 loading on extent of degradation of CBZ 100
Extent of Degradation (%)
90 80 70 60 50 40 30 20 10 0 0
20
40
60
80
100
120
Time (min)
Figure 6 Combined effect of HC and ozone on extent of degradation of CBZ
100
Extent of Degradation (%)
90 80 70 60 50 40 30 20 10 0 0
20
40
60
80
100
120
Time (min)
Figure 7 Combined effect of HC+H2O2+ O3 on extent of degradation of CBZ
120 100
% Degradation
100
91.4
80 58.3
60 40 20
52.9
49.1
38.7 29.4 18
0
Figure 8 Comparison of different approaches in terms of extent of degradation of CBZ
Figure 9 Intermediate analysis using LC-MS
Table 5: Effect of inlet pressure on extent of degradation of CBZ and kinetic rate constant Pressure
Extent of degradation (%)
K× 103 (min-1)
3
10.4
0.6
4
16.5
1.3
5
16.03
1.4
Table 6: Effect of pH on extent of degradation of CBZ and kinetic rate constant pH
Extent of degradation (%)
K× 103 (min-1)
3
31.8
3.1
4
38.7
3.8
5
20.4
1.9
6
22.4
2.1
11
19.0
1.9
Table 7: Comparison of different combined processes in terms of synergistic index Extent of degradation
K× 103 (min-1)
Synergistic Index
Scheme (%) Only HC
38.7
3.8
-
Only UV
18.0
1.3
-
Only H2O2
29.4
2.2
-
Only O3
49.1
4.8
-
HC+ UV
52.9
4.9
0.9
HC+ H2O2
58.3
6.1
1.01
HC + O3
91.4
19.1
2.2
HC+ H2O2 + O3
100
34.7
3.2
Table 8: Comparison of different processes in terms of cavitational yield and total treatment cost Total Cavitation Degradation Yield×105
Scheme (%)
(mg/J)
Energy required
cost
Total Additive
related
to
Treatment cost
power
(kWh)
cost (Rs./L)
(Rs./L)
(Rs./L)
Only HC
38.7
9.15
0.0303
0.27
-
0.27
HC+ UV
52.9
7.45
0.0372
0.33
-
0.33
HC+ H2O2
58.3
13.8
0.0201
0.18
0.13
0.31
HC + O3
91.4
15
0.01857
0.16
-
0.16
HC+ H2O2 + O3
100
15.7
0.01777
0.16
0.13
0.29
HIGHLIGHTS: Degradation of Carbamazepine using combined processes based on hydrodynamic cavitation
Understanding into effect of operating pressure and pH of wastewater
Comparison of different treatment approaches at large scale operation in terms of cavitational yield and economics Combined process gives higher extent of degradation resulting into synergistic effects Optimized approach involving hydrodynamic cavitation, ozone and hydrogen peroxide is the best
S1350-4177(17)30355-3 http://dx.doi.org/10.1016/j.ultsonch.2017.08.001 ULTSON 3806
To appear in:
Ultrasonics Sonochemistry
Received Date: Revised Date: Accepted Date:
8 May 2017 25 June 2017 1 August 2017
Please cite this article as: P. Thanekar, M. Panda, P.R. Gogate, Degradation of Carbamazepine Using Hydrodynamic Cavitation Combined With Advanced Oxidation Processes, Ultrasonics Sonochemistry (2017), doi: http:// dx.doi.org/10.1016/j.ultsonch.2017.08.001
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Degradation of Carbamazepine Using Hydrodynamic Cavitation Combined With Advanced Oxidation Processes
Pooja Thanekar, Mihir Panda, Parag R. Gogate*
Chemical Engineering Department, Institute of Chemical Technology, Matunga, Mumbai 40019, India
*Corresponding Author: E-mail: [email protected] Phone: +91 22 3361 2024 Fax: +91 22 3361 1020
Abstract Degradation of carbamazepine (CBZ), a widely detected recalcitrant pharmaceutical in sewage treatment plant (STP) effluent, has been studied in the present work using combination of hydrodynamic cavitation (HC) and advanced oxidation processes (AOPs). Due to its recalcitrant nature, it cannot be removed effectively by the conventional wastewater treatment plants (WWTPs) which make CBZ a pharmaceutical of very high environmental relevance and impact as well as stressing the need for developing new treatment schemes. In the present study, the effect of inlet pressure (3-5bar) and operating pH (3-11) on the extent of degradation have been initially studied with an objective of maximizing the degradation using HC alone. The established optimum conditions as pressure of 4 bar and pH of 4 resulted in maximum degradation of CBZ as 38.7%. The combined approaches of HC with ultraviolet irradiation (HC+UV), hydrogen peroxide (HC+H2O2), ozone (HC+O3) as well as combination of HC , H2O2 and O3 (HC+H2O2+O3) have been investigated under optimized pressure and operating pH. It was observed that a significant increase in the extent of degradation is obtained for the combined operations of HC+H2O2+O3, HC+O3, HC+H2O2, HC+ UV with the actual extent of degradation being 100%, 91.4%, 58.3% and 52.9% respectively. Kinetic analysis revealed that degradation of CBZ fitted first order kinetics for all the approaches. The processes were also compared on the basis of cavitational yield calculations and also in terms of total treatment cost. Overall, it has been demonstrated that combined process of HC, H2O2 and O3 can be effectively used for treatment of wastewater containing CBZ.
Keywords: Carbamazepine; Hydrodynamic cavitation; advanced oxidation processes; kinetic study; cavitational yield; total treatment cost.
1. Introduction: Carbamazepine (CBZ) is an antiepileptic drug commonly used for treatment of schizophrenia as well as bipolar disorder. Due the chronic administration in high dosages (100-2000 mg daily), the annual production is typically very high [1]. Approximately <3% of the dosed CBZ is excreted in unaltered form, along with the pharmacologically active 10, 11 epoxycarbamazepine and further hydrolyzed dihydroxy derivatives. As CBZ is highly stable, it allows long-term transportation within the aquatic environment [2]. Studies have demonstrated that the removal efficiency of CBZ by conventional wastewater treatment plants (WWTPs) is very low (<10%)[3], which results in presence of CBZ in bio-solids and treated water discharges. Considering these aspects, CBZ can get accumulated in root tissues of plants and also translocated into other parts including beans. CBZ has been reported to have significant on the embryonic cell growth [4]. The chromic exposure of fish to CBZ has been demonstrated to yield reduction in fish steroid hormone which influences the reproduction ability of fish population. Also, low concentration exposure of CBZ caused an adverse effect on histology of kidney and liver, hampering fish development [5]. Thus it becomes imperative to develop an efficient method which will ensure its complete removal from effluents. In literature, various advanced oxidation processes (AOPs) have been reported to be effective techniques for the degradation of complex emerging pollutants[6]. AOPs involves the production of highly oxidizing species (hydroxyl radicals, •OH) for the degradation and also complete mineralization of emerging pollutants. Among the AOPs, cavitation (acoustic and hydrodynamic), photo catalytic oxidation, Fenton (Fe2+/H2O2) and Fenton like processes have been applied with better efficacy for complete removal of organic pollutants[7,8]. Cavitation has shown considerable promise for wastewater treatment application over last few years[7] due to the significant effects in terms of local hot spots, highly reactive free radicals and
intense mixing based on turbulence and liquid circulation [9,10]. All these effects are extremely suitable for the oxidation of complex compounds, both organic as well as inorganic, including the pesticides and the emerging contaminants such as pharmaceutical drugs[11]. The two modes of cavitation generally found suitable for different chemical/physical transformations include acoustic and hydrodynamic cavitation [12]. In acoustic cavitation, high frequency sound waves (16 kHz–2 MHz) are utilized for the generation of cavities based on the variation of pressure in the liquid. Though most commonly applied at laboratory scale for degradation of various pollutants, ultrasonic reactors offer significant problems for large scale operation due to localized nature of intense cavitation zones, lower energy efficiency and higher treatment costs. Hydrodynamic cavitation (HC) reactors have been looked as an energy efficient alternative to ultrasonic reactors [13,14]. In the case of hydrodynamic cavitation, presence of constriction in the liquid flow drives the different stages of cavitation [7] based on the changes in the kinetic energy of the liquid and the local pressure. At the downstream of the constriction, a very high intensity fluid turbulence occurs and generation of oxidants occurs attributed to the violent collapse of the cavities [13]. Various studies have been reported on the degradation of CBZ using AOPs such as photocatalysis[15,16] and Fenton’s reaction[17] operated individually as well as using combined treatment schemes such as sonoelectrochemical oxidation[18], sonophoto catalytic degradation[19],
Hydrodynamic
acoustic
cavitation
(HAC)
[20]
and
combined
Hydrodynamic cavitation- hydrogen peroxide (HC/H2O2) [21] approach. Zupanc et al. [21] investigated the removal efficiencies of five model pharmaceuticals as ibuprofen, naproxen, ketoprofen, carbamazepine and diclofenac using different approaches based on biological processes, HC and UV treatment. The removal extent of CBZ using the combined approach of HC/H2O2 was reported to be around 80% within 30 min under the
optimized parameters of 20ml of 30% H2O2 and initial pressure of 6 bar. The combined operation of three processes i.e. biological process, HC and UV treatment under optimized conditions resulted in maximum removal extent as >98%. Braeutigam et al. [20] investigated a novel approach of Hydrodynamic-Acoustic-Cavitation (HAC) for the degradation of CBZ and reported that 96% degradation was obtained within 15 min under optimized conditions. The observed synergistic effect was 63% as compared to the addition of individual approaches. Exposito et al. [19] studied photo-Fenton degradation of CBZ combined with ultrasound (US/UV/H2O2/Fe) and reported around 60 % of mineralization. Tran et al. [18] reported synergistic effects of ultrasound in the sonoelectrochemical oxidation for degradation of CBZ. The degree of synergy was reported to be strongly dependent on the current intensity. Dong et al. [22] studied degradation of CBZ using direct and sensitized photolysis. The sensitized photolysis on five days exposure resulted in degradation in the range of 67–98%. Ghauch et al. [23] investigated CBZ oxidation using an improved Fenton’s process based on combination of ultrasound, zero valent iron and hydrogen peroxide. It was reported that almost 90% degradation of CBZ was obtained using optimized loading of Fe0 acting as pseudo catalyst combined with low ultrasound (US) frequency (40 kHz) and H2O2. Deng et al. [24] investigated CBZ degradation using UV irradiation in the presence of oxidants such as hydrogen peroxide (H2O2), peroxymonosulfate (PMS), and persulfate (PS). Higher extent of degradation was observed in the presence of oxidant PS as compared to H2O2 and PMS. Detailed analysis of literature revealed that many studied are available reporting the use of AOP for degradation of CBZ, but no studies have been reported based on combination of HC with other AOPs such as H2O2, Ozone and UV treatment. Considering this analysis, the present work focuses on developing an efficient combined oxidation approach based on HC which can lead to significant efficacy for degradation, which can prompt possible commercial
applications. The work also compares the effectiveness of processes such as HC/H2O2, HC/ozone, and HC/UV in terms of cavitational yield and the treatment costs. 2. Materials and Methodology: 2.1 Materials Carbamazepine was obtained from High Media Pvt. Ltd., Mumbai, India. Hydrogen peroxide (30%, w/v) of AR grade and Acetonitrile of HPLC grade were obtained from Thomas Baker Pvt. Ltd., Mumbai, India. The freshly prepared distilled water, using the laboratory distillation unit obtained from Borosil Glass Work Ltd., Mumbai, India was used for preparation of solutions of known concentrations. 2.2 Experimental set up The schematic representation of experimental setup of HC used in the present work has been depicted in Fig.1. The setup consists of a closed loop circuit including a feed tank, a reciprocating pump of power rating 1.1 kW, pressure gauges, flanges to accommodate the cavitating device (slit venturi) and control valves to control the flow rate through the main and bypass lines. The setup also includes a main line housing the slit venturi and a bypass line to control the flow rate through the main line. The geometric details of slit venturi used as cavitating device in the preset work have been reported by Patil et al. [25]. For the combined approach of HC and UV, two UV lamps (Philips TUV 4 W/G4T5) of output power 8 W each with a dominant wavelength of 254 nm were inserted inside the feed tank of HC reactor. For combined approach of HC and H2O2, different ratios of CBZ: H2O2 as 1:1(10 mg/L H2O2), 1:2 (20 mg/L H2O2), 1:3(30 mg/L H2O2), 1:4(40 mg/L H2O2), 1:5(50 mg/L H2O2), and 1:6(60 mg/L H2O2) have been used. Ozone generator (model-DOZ400) procured from Eltech Engineering, Mumbai has been used for combined approach of HC and ozone. Ozone gas was introduced into the feed tank at the required flow rate using a ceramic diffuser.
2.3
Methodology
For all the degradation experiments, 4L aqueous solution of 10ppm CBZ was taken in the feed tank. After starting the circulation pump, the pressure at the inlet was adjusted by closing the by-pass line. Different inlet pressures over the range of 3 to 5 bar have been used in the study. The constant feed temperature of 35°C was achieved based on the circulation of cooling water through the jacket. To study the effect of pH on the extent of degradation, different pH values ranging from 3-11 were varied in the study with adjustments based on the use of 0.1 M H2SO4 and 0.1 M NaOH as required. All the experimental runs were performed for a treatment time of 120 min and samples were removed at regular time interval of 20 min for the analysis of extent of degradation. Experiments related to the combination of HC and AOPs were then performed under optimum inlet pressure and pH. In order to study efficacy of combined operation of HC/UV process on extent of degradation, UV lamp of 8W and 16 W placed inside a jacketed quartz cylinder was inserted vertically inside the feed tank of HC reactor. The effect of addition of hydrogen peroxide (H2O2) on the degradation of CBZ in presence of HC has also been studied at different loadings of H2O2 using the ratios of CBZ: H2O2 from 1:1 to 1:6 for the fixed initial concentration of CBZ (10ppm). The combined effect of HC/ozone on extent of degradation of CBZ has been studied by injecting ozone inside the feed tank of HC reactor at flow rate of 400 mg/h. 2.4 Analysis CBZ concentration was monitored using the Agilent High Performance Liquid Chromatography (HPLC) unit with an Agilent eclipse plus C-18 column having dimensions of 4.6×100 mm and particle size of 3.5 µm. The mobile phase of acetonitrile: water (40:60) with the flow rate of 1mL/min was used in the work. The eluted CBZ was detected at wavelength of 220 nm using UV detector. Integral method of analysis was used for fitting the kinetic model to the degradation process. The treatment cost was also calculated to compare
the efficacy of the combination approaches with the individual treatment approaches. The intermediates formed during the degradation of CBZ were identified using liquid chromatography–mass spectroscopy (LC- MS) technique. 3. Results and Discussion 3.1 Effect of inlet pressure The studies related to understanding the effect of inlet pressure were performed at natural pH of solution (11.6). The obtained results for the effect of inlet pressure on extent of degradation of CBZ over the range of 3 -5 bar has been depicted in Fig.2 (a). The integral analysis was also performed to find the kinetic rate constants and reaction order. Fig.2 (b) shows the plot of ln (Ca0/Ca) vs. time for the first order kinetics and the obtained results for the kinetic rate constant are given in Table 1. It was observed that at 4 bar inlet pressure, maximum extent of degradation obtained was 16.5% with first order rate constant of 1.1×10 -3 min-1 using HC reactor with slit venturi as cavitating device. Typically, the optimum value of pressure is in the range of 4-6 bar for low pressure configurations such as orifice plate and venturi [26]. From Fig. 2(a), it can be observed that the extent of degradation increases with an increase in the inlet pressure up to 4 bar and any further increase beyond this results in only marginal decrease in the extent of degradation. The cavitational intensity increases with an increase in pressure based on a lower cavitation number. However, further increase in pressure beyond optimum value leads to the formation of cavity cloud which in turn reduces cavitational intensity resulting in a decrease in the extent of degradation [27,28]. Saharan et al. [29] have confirmed the cavity cloud formation inside a transparent venturi by performing photographic study at different inlet pressures. Wang and Zhang [30] studied the alachlor herbicide degradation using HC and also reported the increase in degradation rate with an increase in inlet pressure from 0.2 MPa to 0.6 MPa. Chakinala et al. [31] studied the treatment of real industrial effluent using combined operation of HC and heterogeneous
advanced Fenton process (AFP) in presence of zero valent iron as the catalyst. It was reported that 60% TOC removal is obtained at 1500psi (10,340kPa), whereas at low pressure such as 1000psi (6893.3kPa) and 500psi (3446.7kPa) the extent of TOC removal was only about 52% and 50% respectively. Bagal and Gogate [32] have also reported similar effect of pressure on extent of degradation of pharmaceutical drug, diclofenac sodium. For 20 ppm aqueous solution of diclofenac sodium, maximum degradation is at 3 bar pressure was 20.81% using venturi as cavitating device. Jadhav et al. [33] investigated the synergistic effect of HC and H2O2 on degradation of imidacloprid. The extent of degradation has been investigated at different inlet pressures (5-20 bar) using circular venturi as a cavitating device. It was reported that the rate of degradation of imidacloprid increased with an increase in pressure till an optimum pressure of 15 bar. The comparison of the extents of degradation obtained for different pollutants at varying pressure reveals that though the trend is similar, the optimum value of pressure is different and also the extent of intensification obtained at varying pressures is different. This analysis confirms the necessity of performing the detailed investigation related to effect of inlet pressure and hence establishes the importance of the current work. 3.2Effect of pH The experiments for understanding the effect of pH on the extent of degradation were performed at varying pH over the range from 3-11, at optimized 4 bar inlet pressure. The obtained results for the extent of degradation and kinetic rate constant have been shown in the Fig. 3 and Table 2. It was observed that minimum degradation was obtained as 19.0% at pH 11, whereas maximum degradation of 38.7 % was achieved at pH 4. It is also interesting to observe that the rate of degradation is higher in the initial stages and lowers after about 60 min of operation which is a typical first order behavior and also some contribution from the dissolved gases in the initial period drives such trend. The trend is significantly seen for pH
of 4 where maximum degradation is observed. The first order kinetic rate constant was also observed to decrease as pH increases. Under the acidic conditions, generation of OH radical is favored as its oxidation potential is higher. Remaining experiments were performed keeping pH of solution constant at 4. Deng et al. [24] have also reported that maximum degradation occurred at low pH. Patil and Gogate [28] reported that the degradation of methyl parathion using hydrodynamic cavitation was higher at acidic condition ( pH as 3) than alkaline pH (pH as 8.2). Pradhan and Gogate [34] also reported that maximum degradation of p-nitrophenol was obtained as 63.2% using combination of HC and Fenton chemistry at pH 3.75, whereas at pH 8 (alkaline condition), considerably lower removal (35.7 %) was obtained. Ghauch et al. [23] also observed significant removal of CBZ at pH 3 (95%) with lower removal at pH 5 (60%) using ultrasonic/Fe0/H2O2 systems. Rajoriya et al. [35] studied the decolorization of Rhodamine 6G dye using HC coupled with other oxidative agents such as H2O2 and ozone. It was reported that the decolorization rate was higher in basic conditions (optimum value of 10.0) than acidic conditions (pH of 2). The maximum extent of degradation of 32.1% was obtained at optimized pH of 10 with kinetic rate constant of 3×10-3min-1. The comparison of the observed trends in different literature illustrations revealed that exact optimum pH and the extent of variation in the degradation obtained is different and hence effect of pH was studied in details for CBZ. 3.3 Combined operation of HC/UV: In order to study the efficacy of combined operation of HC and UV, degradation of CBZ was studied by inserting UV lamp (8W and 16W) inside the feed tank. The obtained results for the combination approach have been given in Fig. 4. It can be observed that the maximum extent of degradation (52.9%) was obtained using UV lamp of power 16W and lower extent of degradation was obtained at 8W power of UV (45.4%). Using only HC resulted in an extent of degradation as 38.7% under otherwise similar conditions. Thus it can be said that
use of UV in combination with HC helps in increasing the extent of degradation by about 15 to 40% depending on the rated power as compared to only HC (considered as base value for calculations of percentage increase). The degradation of CBZ using combined approach also followed first order kinetics and rate constant obtained for combination with 16W UV lamp was 4.9×10-3 min-1. In order to compare individual approach of UV with combined treatment of HC+UV, set of experiments were performed by closing main line valve of HC setup so that the solution bypasses the cavitating device and is only exposed to UV irradiation. The observed extent of degradation using only 16W UV lamp was 18% whereas earlier studies established that degradation obtained using only HC was 38.7%. It was thus established that the combined operation gives higher extents of degradation. UV irradiation generates OH radicals via photolysis of water molecule, whereas in HC, collapse of cavities yields OH radicals. Hence, combined operation of HC/UV leads to generation of more OH radicals than HC alone or UV alone which results in an increase in the extent of degradation[32]. The synergistic index based on degradation rate constant can be calculated by the following Eq. (1)
=
=
. × .× . ×
= 0.9
(1)
The obtained synergistic index revealed that the combined method of HC+UV results in better efficiency that individual method but no synergism was observed. Deng et al. [24] investigated CBZ degradation using UV (253.7 nm) irradiation in combination with oxidants like hydrogen peroxide (H2O2), peroxymonosulfate (PMS) and persulfate (PS). It was reported that maximum degradation efficiency was obtained using the UV/PS combination followed by UV/H2O2 and minimum for the UV/PMS combination. Pereira et al. [36] investigated UV photolysis and UV/H2O2 oxidation of pharmaceutically active compounds including ketoprofen, naproxen, carbamazepine, ciprofloxacin, clofibric acid, and iohexol. It was reported that negligible removal of CBZ was observed when
subjected to only UV irradiation at intensity of 100mJ/cm2. However enhanced removal of CBZ up to 13% was observed when 10mg/L of hydrogen peroxide was added in sample before its exposure to UV irradiation, confirming the role of hydrogen peroxide in enhancing the free radical formation. Zupanc et al. [21] reported that use of hydrodynamic cavitation with photolysis resulted in beneficial results for the degradation of CBZ along with other pharmaceutical compounds including diclofenac, ibuprofen, naproxen, ketoprofen and active metabolite of the lipid regulating agent clofibric acid. Barik and Gogate [37,38] studied the extent of degradation of 4-chloro 2-aminophenol using combined process of US as well as HC with AOPs such as photolysis and ozone. In the case of US coupled with UV, the extent of degradation found was more (88.42%) than the individual processes of US (24.17%) and UV (80.8%). Also in case of HC combined with UV and O3, maximum extent of degradation obtained was 96.85% with TOC reduction of 73.6%. 3.4 Combined operation of HC and hydrogen peroxide (H2O2) Approach of hydrogen peroxide in combination with HC was also investigated and observed results have been depicted in Fig. 5. The effect of different loadings of H2O2 using the ratios of CBZ: H2O2 as 1:1, 1:2, 1:3, 1:4,1:5 and 1:6 was investigated. It was observed that the extent of degradation increases from 31% to 58.3% as loading of H2O2 increases from 1:1 to 1:5. Also the reaction fitted to first order kinetics and rate constant observed at 1:5 H2O2 loading was the maximum as 6.1×10 -3min-1. Further increase in H2O2 loading to 1:6 resulted in a decrease in the extent of degradation. The lower degradation at highest loading is attributed to scavenging action of residual H2O2. Beyond the optimum loading of H2O2, generated OH radicals react with H2O2 as given by following reaction(2) [39]. .
H2O2 +OH
H2O+ HO2
(2)
This phenomenon of scavenging is also confirmed from the literature reports though different optimum values of H2O2 loading are observed. Mishra and Gogate[40] investigated the
application of combined approach of HC and H2O2 on degradation of Rhodamine B by taking five different concentrations of H2O2, ranging from 10mg/L to 200mg/L. It was reported that degradation of Rhodamine B increased up to 99.9% in the presence of 200 mg/L H2O2 with TOC reduction of 55%. Also, the combined effect of HC and H2O2 was studied by Jadhav et al. [33] for the degradation of imidacloprid insecticide and 100% degradation was reported in 45 min of operation at molar ratio of imidacloprid : H2O2 as1:40. . In the present work, the extent of degradation of CBZ and rate constant obtained using only H2O2 (1:5 ratio) was 29.4 and 2.2×10-3 min-1 respectively. The operation of using only hydrogen peroxide induced degradation was again based on closing main line valve of HC setup blocking the flow though cavitating device. To compare efficiency of hybrid processes (HC+ H2O2) with individual process, synergistic index was again calculated as per the following Eq. (3):
=
=
.× .× . ×
= 1.01
(3)
The obtained synergistic index confirmed that the combined method is better than the individual method and also gives more than the additive effect. The observed trend is attributed to enhanced generation of OH* radicals by increasing the rate of dissociation of H2O2 in presence of HC. Also, HC generates turbulence which increases diffusivity leading to elimination of mass transfer resistances for the pollutant [33]. Zupanc et al. [21] have also reported beneficial results for the combination of hydrodynamic cavitation and hydrogen peroxide with much higher degradation as 89% under optimum dosage of hydrogen peroxide as 20 mL as compared to only 24% degradation for the operation of only hydrodynamic cavitation. 3.5 Combined operation of HC and Ozone Ozone is a strong oxidant with standard reduction potential (E0) of 2.07 V and can be effectively used for degradation of complex compounds such as pesticides, dyes,
pharmaceuticals etc. [41]. The reaction of ozone with pollutants follows two types of mechanism viz. direct molecular attack and indirect reaction involving OH radicals [42]. Ozone coupled with HC can result in more degradation rates as compared to HC alone and ozone alone, which is attributed to elimination of mass transfer resistance due to cavitational effects along with formation of highly reactive OH radicals [43,44]. In this study, ozone loading of 400 mg/h was injected directly inside the feed tank containing CBZ solution, using ozone generator for 120 min of treatment. From the results depicted in Fig.6, it can be observed that the extent of degradation and rate constant obtained was 91.3% and 19.1×10 -3 min-1 respectively under optimized conditions. In order to obtain extent of degradation and rate constant of CBZ using only ozone, the main line valve of HC setup was closed so that all the flow goes through bypass line and ozone loading of 400 mg/h was injected inside the tank. The extent of degradation and rate constant obtained using only ozone was 49.1% and 4.8×10 -3 min-1 respectively. To compare efficiency of combined process of HC and Ozone with individual process, synergistic index was calculated using following Eq. (4)
=
!
=
.× .× .×
= 2.2
(4)
The obtained synergistic index demonstrates that the combined effect is more efficient over the individual method. The cavitation generates turbulence which overcomes mass transfer limitations and also results in decomposition of ozone into reactive species like nascent oxygen and OH* radicals which in turn increases extent of degradation. The combined mechanism of elimination of mass transfer resistance (dominant in the present case due to the gas liquid nature of system as compared to other combinations involving hydrogen peroxide or UV light) and production of additional oxidants gives the maximum synergistic effect for the current combination. Barik and Gogate [45] have reported similar increase in the extent of degradation of 2,4dichlorophenol using combination of US/Ozone/Catalyst. Gogate and Patil [43] studied the
degradation of triazophos using the combined process of HC and O3. It was reported that introducing ozone in the feed tank gave about 86.68% degradation, whereas 49.67% and 59.36% degradation was obtained using individual approach of HC and O3 alone respectively. Patil and Gogate [44] reported complete degradation of dichlorvos pesticide with 93% removal of TOC in 30 min of treatment using the combined operation of ozone (1.95 g/h) and sonication. Similarly, effect of combination of HC and ozone on degradation of Rhodamine 6G dye was studied by Rajoriya et al. [35]. It was reported that 100% decolorization observed in 10 min at ozone feed rate of 3 g/h. TOC reduction of 73.19% with rate constant 10.9×10 -3min-1 was also reported in 120 min of reaction time at ozone feed rate of 3 g/h. 3.6 Combined operation of HC+H2O2+O3 The combination of HC, H2O2 (CBZ: H2O2 =1:5) and O3 (flow rate= 400mg/h) was also investigated in the work and observed to give complete degradation of CBZ within 100 min of treatment as per the results represented in Fig. 7. To compare individual approaches with combined treatment, set of experiments were performed by closing main line valve of HC set up so that all the flow gores through the by-pass line allowing restriction to flow passage through cavitation chamber. By this method, the extent of degradation for the individual treatments such as UV, H2O2 and O3 were obtained. From Fig.8, it can be observed that extent of degradation of combined treatment approaches such as HC+UV, HC+H2O2, HC+O3, HC+H2O2+O3 was higher as compared to the individual approach of HC, UV, H2O2 and O3. This is attributed to generation of more OH radicals as well as enhancement in the mass transfer due to cavitation [43]. The obtained values for the synergistic Index are given in Table 5 whereas calculation for combined HC+H2O2+O3 is shown as follows:
=
!
=
.#× .× . × .×
= 3.2
(5)
The observed synergistic index for combined operation of HC+H2O2+O3 was higher as compared to other approaches which may be attributed to generation of more OH radicals in combined operations than individual operation and also stronger contribution of the mass transfer elimination.
3.7 Analysis of intermediates: Intermediate analysis was performed for the combined approach of HC with H2O2 and O3 where maximum extent of degradation (100%) was achieved. Intermediates were analyzed using LC-MS technique. The prominent peaks were observed at m/z 141.04, 183.08, 166.02, 296.13 and 187.16 in the mass spectra. The compounds detected based on free radical oxidation of CBZ were 2-Aminomuconate 6-semialdehyde (A), Benzoquinone acetic acid (B), Racepinephrine (C), Di-demethylcitalopram (D), N1-Acetylspermidine (E) ,swietenine (F) as depicted in Fig. 9. 3.8 Cavitational yield and cost of treatment: Cavitational yield is defined as desired chemical change obtained per unit power dissipation. In hydrodynamic cavitational reactors, the energy delivered by the reciprocating pump is main energy dissipation source for generating cavitation [14]. The power dissipation per unit volume was obtained to be 5.87 W/L based on flow rate basis (Power= flow rate ×pressure). From the results given in Table 4, the cavitational yield (detailed calculation has been given in appendix I) for HC+H2O2+O3 was observed to be higher (15.7×10-5mg/J) as compared to other processes. Patil and Gogate [28,44] have obtained cavitational yield of 4.44×10
-6
mg/J
for the 44 % of extent of degradation for the 20 ppm initial solution of methyl parathion, whereas 8.08 × 10 −5 mg/J of cavitational yield was obtained for degradation of dichlorvos pesticide using combined effect of US + solar + TiO2. The operating cost of the treatment was also calculated from the cavitational yield given in
Table 4. It was observed that the treatment cost requirement for combined process of HC+H2O2+O3 is 0.16 Rs/L which is quite low as compared to other treatment methods. The operation of HC alone would cost around 0.27 Rs/L which is higher as compared to other combined approaches based on HC. Therefore to obtain better cost efficiency, the combined process is preferable. Patil and Gogate[44] reported cost estimation for degradation of dichlorvos using combined ultrasound coupled with AOPs and also observed that higher cost was required for individual operation related to use of ultrasound (5.69 Rs/L), H2O2 (6.37 Rs/L), and TiO2 (4.16 Rs/L) as compared to the combined processes.
4 .Conclusions: The present work demonstrated the effective use of HC coupled with AOPs such as UV irradiation, H2O2 and O3 for degradation of CBZ. The use of HC alone for degradation of CBZ resulted in 38.7% degradation, whereas combination of HC+H2O2+O3 resulted in almost complete degradation within 100 min at optimized loadings. It has been conclusively established combined treatment approaches such as HC+UV, HC+H2O2, HC+O3, HC+H2O2+O3 resulted in showing enhanced reaction rates as compared to the individual approach of HC, UV, H2O2 and O3. The combination of HC+H2O2+O3 resulted in 100 % degradation of CBZ in 100 min of treatment with operating cost of 0.16 Rs/L. The calculated synergistic index confirmed the effectiveness of combined approaches as compared to the individual approaches. Also, it has been observed that the use of hydrodynamic cavitation alone may not give satisfactory results of extent of degradation of target compound and hence it is recommended to use HC coupled with other appropriate AOPs. Overall it can be concluded that using optimized combination of HC with ozone and hydrogen peroxide is the best treatment approach for the complete degradation of CBZ in most economic manner.
Appendix-I Sample calculation for Cavitational yield: (mg/J) Power dissipated for 4 L reaction volume (W) = Flow rate (m3/s) × ∆P (N/m2) = 78.12×10 -6×3×105 = 23.43 Power rating of pump (based on flow rate basis) =23.43 W Power dissipated per unit volume= 23.43/4 = 5.87 W/L Extent of degradation= Cavitational yield=
×.#
= 3.87mg/L
+,-./- 01 2.34525-60/ 708.4 26996:5-60/
=
.# ;.#× ×
= 9.15×10-5 mg/J
Sample calculation for Cost of treatment: Cavitational yield = 9.15×10-5 mg/J Energy required for removal of CBZ = 10/9.15×10-5 = 0.03035 kWh Considering 1 kWh = Rs. 8.78 (Maharashtra State Electricity Distribution Co. Ltd., 2012) Cost of treatment = 0.030 × 8.78 = 0.27Rs.
Acknowledgement: Authors would like to acknowledge the funding of Department of Science and Technology under the Water Technology initiative scheme (Project reference: DST/TM/WTI/2K15/126(G)). Authors would also like to acknowledge the funding of TEQIP INN scheme for fellowship to Mihir Panda
5. References [1]
T. Kosjek, H.R. Andersen, B. Kompare, A. Ledin, Fate of Carbamazepine during Water Treatment, Environ. Sci. Technol. 43 (2009) 6256–6261.
[2]
S.M. C.Tixier, H. Singer, S. oellers , S.R. Muller,Occurrence and Fate of Occurrence
and Fate of Carbamazepine, Clofibric Acid, Diclofenac, Ibuprofen, Ketoprofen, and Naproxen in Surface Waters, Environ. Sci. Technol. 37 (2003) 1061–1068. [3]
Y. Zhang, S. Geiben, C. Gal, Chemosphere Carbamazepine and diclofenac : Removal in wastewater treatment plants and occurrence in water bodies, Chemosphere. 73 (2008) 1151–1161.
[4]
S. Castiglioni, E. Zuccato, R. Fanelli, D. Vigetti, C. Rossetti, D. Calamari, Effects of a Complex Mixture of Therapeutic Drugs at Environmental Levels on Human Embryonic Cells, Environ. Sci. Technol. 40 (2006) 2442–2447.
[5]
M. Galus, N. Kirischian, S. Higgins, J. Purdy, J. Chow, S. Rangaranjan, H. Li, C. Metcalfe, J.Y. Wilson, Chronic , low concentration exposure to pharmaceuticals impacts multiple organ systems in zebrafish, Aquat. Toxicol. 132–133 (2013) 200– 211.
[6] I. Michael, Z. Frontistis, D. Fatta-kassinos, Removal of Pharmaceuticals from Environmentally Relevant Matrices by Advanced Oxidation Processes ( AOPs ), Chapter in book by M. Petrovic, S. Perez, D. Barcelo (Eds), Analysis, Removal, Effects and Risk of Pharmaceuticals in the Water cycle 2nd ed., Elsevier U.K.(2013) 345-408 [7]
P.R. Gogate, Cavitational reactors for process intensification of chemical processing applications: A critical review, Chem. Eng. Process. Process Intensif. 47 (2008) 515– 527.
[8]
H. Wang, W. Liang, Q. Zhang, W. Jiang, Solar-light-assisted Fenton oxidation of 2,4dinitrophenol (DNP) using Al2O3 -supported Fe ( III ) -5-sulfosalicylic acid (ssal) complex as catalyst, Chem. Eng. J. 164 (2010) 115–120.
[9]
T.G. Leighton, Bubble population phenomena in acoustic cavitation,Ultrason. Sonochem. 2 (1995) 123–136.
[10] P. Cintas, J. Luche, Green chemistry: The sonochemical approach, Green Chem. 43 (1999) 115–125. [11] P.R. Gogate, A.B. Pandit, Application of Cavitational reactors for cell disruption for recovery of intracellular enzymes, J.Chem.Technol.Biotechnol.1093 (2008) 1083– 1093. [12] P.R. Gogate, A.M. Kabadi, Authors personal copy A review of applications of cavitationin biochemical engineering / biotechnology, Biochem. J. 44 (2009) 60–72 [13] P.R. Gogate, A.B. Pandit, A review and assessment of hydrodynamic cavitation as a technology for the future, Ultrason. Sonochem. 12 (2005) 21–27. [14] P.R. Gogate, I.Z. Shirgaonkar, M. Sivakumar, P. Senthilkumar, N.P. Vichare, A.B. Pandit, Cavitation reactors: Efficiency assessment using a model reaction, AICHE J. 47 (2001). [15] M.W. Lam, S.A. Mabury, Photodegradation of the pharmaceuticals atorvastatin, carbamazepine, levofloxacin, and sulfamethoxazole in natural waters, Aquat. Sci. 67 (2005) 177–188. [16] S.Chiron, C. Minero, D. Vione, Photodegradation Processes of the Antiepileptic Drug Carbamazepine, Relevant To Estuarine Waters, Environ. Sci. Technol. 40 (2006) 5977–5983. [17] A. Karpinska, A. Sokol, J. Karpinska, Studies on the kinetics of carbamazepine degradation in aqueous matrix in the course of modified Fenton’s reactions, J. Pharm.
Biomed. Anal. 106 (2015) 46–51. [18] N. Tran, P. Drogui, S. Brar, A. Coninck, Synergistic effects of ultrasounds in the sonoelectrochemical oxidation of pharmaceutical carbamazepine pollutant, Ultrason. Sonochem. 34 (2017) 380–388. [19] A.J. Exposito, D.A. Patterson, J.M. Monteagudo, A. Duran, Sono-photo-degradation of carbamazepine in a thin falling film reactor: Operation costs in pilot plant, Ultrason. Sonochem. 34 (2017) 496–503. [20] P. Braeutigam, M. Franke, R.J. Schneider, A. Lehmann, A. Stolle, B. Ondruschka, Degradation of carbamazepine in environmentally relevant concentrations in water by Hydrodynamic-Acoustic- Cavitation ( HAC ), Water Res. 46 (2012) 2469–2477. [21] M. Zupanc, T. Kosjek, M. Petkovsek, M. Dular, B. Kompare, B. Sirok, Z. Blazeka, E. Heath, Removal of pharmaceuticals from wastewater by biological processes, hydrodynamic cavitation and UV treatment, Ultrason. Sonochem. 20 (2013) 1104– 1112. [22] M.M. Dong, R. Trenholm, F.L. Rosario-Ortiz, Photochemical degradation of atenolol, carbamazepine, meprobamate, phenytoin and primidone in wastewater effluents, J. Hazard. Mater. 282 (2015) 216–223. [23] A. Ghauch, H. Baydoun, P. Dermesropian, Degradation of aqueous carbamazepine in ultrasonic/Fe0/H2O2 systems, Chem. Eng. J. 172 (2011) 18–27. [24] J. Deng, Y. Shao, N. Gao, S. Xia, C. Tan, S. Zhou, X. Hu, Degradation of the antiepileptic drug carbamazepine upon different UV-based advanced oxidation processes in water, Chem. Eng. J. 222 (2013) 150–158.
[25]
P.N. Patil, S.D. Bote, P.R. Gogate, Degradation of imidacloprid using combined advanced oxidation processes based on hydrodynamic cavitation, Ultrason. Sonochem. 21 (2014) 1770–1777.
[26] P.R. Gogate, P.N. Patil, Combined treatment technology based on synergism between hydrodynamic cavitation and advanced oxidation processes, Ultrason. Sonochem. 25 (2015) 60–69. [27] M. V. Bagal, P.R. Gogate, Degradation of 2,4-dinitrophenol using a combination of hydrodynamic cavitation, chemical and advanced oxidation processes, Ultrason. Sonochem. 20 (2013) 1226–1235. [28] P.N. Patil, P.R. Gogate, Degradation of methyl parathion using hydrodynamic cavitation: Effect of operating parameters and intensification using additives, Sep. Purif. Technol. 95 (2012) 172–179. [29] V.K. Saharan, M.P. Badve, A.B. Pandit, Degradation of Reactive Red 120 dye using hydrodynamic cavitation, Chem. Eng. J. 178 (2011) 100–107. [30] X. Wang, Y. Zhang, Degradation of alachlor in aqueous solution by using hydrodynamic cavitation, J. Hazard. Mater. 161 (2009) 202–207. [31] A.G. Chakinala, P.R. Gogate, A.E. Burgess, D.H. Bremner, Industrial wastewater treatment using hydrodynamic cavitation and heterogeneous advanced Fenton processing, Chem. Eng. J. 152 (2009) 498–502. [32] M. V. Bagal, P.R. Gogate, Degradation of diclofenac sodium using combined processes based on hydrodynamic cavitation and heterogeneous photocatalysis, Ultrason. Sonochem. 21 (2014) 1035–1043.
[33] S. Raut-jadhav, V. Kumar, D. Pinjari, S. Sonawane, D. Saini, A. Pandit, Synergetic effect of combination of AOP ’ s ( hydrodynamic cavitation and H2O2) on the degradation of neonicotinoid class of insecticide, J. Hazard. Mater. 261 (2013) 139– 147. [34] A.A. Pradhan, P.R. Gogate, Removal of p-nitrophenol using hydrodynamic cavitation and Fenton chemistry at pilot scale operation, Chem. Eng. J. 156 (2010) 77–82. [35] S. Rajoriya, S. Bargole, V.K. Saharan, Degradation of a cationic dye (Rhodamine 6G) using hydrodynamic cavitation coupled with other oxidative agents: Reaction mechanism and pathway, Ultrason. Sonochem. 34 (2017) 183–194. [36] V.J. Pereira, K.G. Linden, H.S. Weinberg, Evaluation of UV irradiation for photolytic and oxidative degradation of pharmaceutical compounds in water, Water Res. 41 (2007) 4413–4423. [37] A.J. Barik, P.R. Gogate, Degradation of 4-chloro 2-aminophenol using combined strategies based on ultrasound, photolysis and ozone, Ultrason. Sonochem. 28 (2016) 90–99. [38] A.J. Barik, P.R. Gogate, Degradation of 4-chloro 2-aminophenol using a novel combined process based on hydrodynamic cavitation, UV photolysis and ozone, Ultrason. Sonochem. 30 (2016) 70–78. [39] A.L. Patil, P.N. Patil, P.R. Gogate, Degradation of imidacloprid containing wastewaters using ultrasound based treatment strategies, Ultrason. Sonochem. 21 (2014) 1778–1786. [40] K.P. Mishra, P.R. Gogate, Intensification of degradation of Rhodamine B using hydrodynamic cavitation in the presence of additives, Sep. Purif. Technol. 75 (2010)
385–391. [41] K. Chandrasekara Pillai, T.O. Kwon, I.S. Moon, Degradation of wastewater from terephthalic acid manufacturing process by ozonation catalyzed with Fe2+, H2O2 and UV light: Direct versus indirect ozonation reactions, Appl. Catal. B: Environ. 91 (2009) 319–328. [42] R.K. Joshi, P.R. Gogate, Degradation of dichlorvos using hydrodynamic cavitation based treatment strategies, Ultrason. Sonochem. 19 (2012) 532–539. [43] P.R. Gogate, P.N. Patil, Combined treatment technology based on synergism between hydrodynamic cavitation and advanced oxidation processes, Ultrason. Sonochem. 25 (2015) 60–69. [44] P.N. Patil, P.R. Gogate, Degradation of dichlorvos using hybrid advanced oxidation processes based on ultrasound, J. Water Process Eng. 8 (2015) 58–65. [45] A.J. Barik, P.R. Gogate, Degradation of 2,4-dichlorophenol using combined approach based on ultrasound, ozone and catalyst, Ultrason. Sonochem. (2016).
List of Figures: Figure 1 Schematic representation of HC reactor Figure 2 (a) Effect of inlet pressure on extent of degradation of CBZ Figure 2 (b) Kinetic data fitting for the degradation of CBZ at different operating pressure Figure 3 Effect of pH on extent on degradation of CBZ Figure 4 Degradation of CBZ using combined approach of HC and UV radiation Figure 5 Degradation of CBZ using combined approach of HC and H2O2 loading Figure 6 Degradation of CBZ using combined approach of HC and ozone Figure 7 Degradation of CBZ using combined approach of HC+H2O2+ O3 Figure 8 Comparison of different approaches in terms of extent of degradation of CBZ Figure 9 Analysis of intermediates using LC-MS List of Tables: Table 1: Effect of inlet pressure on extent of degradation of CBZ and kinetic rate constant Table 2: Effect of pH on extent of degradation of CBZ and kinetic rate constant Table 3: Comparison of different combined processes in terms of synergistic index Table 4: Comparison of cavitational yield and total treatment cost
Figure 1 Schematic representation of HC reactor
18
P= 3 bar
P= 4 Bar
P= 5 Bar
Extent of Degradation (%)
16 14 12 10 8 6 4 2 0 0
20
40
60
80
100
120
Time (min)
Figure 2 (a) Effect of pressure on extent of degradation of CBZ
P= 3 bar
P= 4 bar
P= 5 bar
0.2 y = 0.0014x R² = 0.9679
0.18 0.16
ln Ca0/Ca
0.14
y = 0.0011x R² = 0.8424
0.12 0.1 0.08
y = 0.0006x R² = 0.897
0.06 0.04 0.02 0 0
20
40
60
80
100
120
Time (min)
Figure 2 (b) Kinetic data fitting for the degradation of CBZ at different operating pressure
Extent of Degradation (%)
50
pH = 3
pH = 4
pH = 5
pH = 6
20
40
60
80
pH=11
40
30
20
10
0 0
100
120
Time (min)
Figure 3 Effect of pH on extent of degradation of CBZ
60
Extent of Degradation (%)
8 Watt
16 Watt
50
40
30
20
10
0 0
20
40
60
80
100
120
Time (min)
Figure 4 Combined effect of HC and UV radiation on extent of degradation of CBZ
70
H2O2 (1:3) H2O2 (1:2) H2O2 (1:6)
Extent of degradation (%)
60
H2O2 (1:4) H2O2 (1:1) H2O2 (1:5)
50 40 30 20 10 0 0
20
40
60
80
100
120
Time (min)
Figure 5 Combined effect of HC and H2O2 loading on extent of degradation of CBZ 100
Extent of Degradation (%)
90 80 70 60 50 40 30 20 10 0 0
20
40
60
80
100
120
Time (min)
Figure 6 Combined effect of HC and ozone on extent of degradation of CBZ
100
Extent of Degradation (%)
90 80 70 60 50 40 30 20 10 0 0
20
40
60
80
100
120
Time (min)
Figure 7 Combined effect of HC+H2O2+ O3 on extent of degradation of CBZ
120 100
% Degradation
100
91.4
80 58.3
60 40 20
52.9
49.1
38.7 29.4 18
0
Figure 8 Comparison of different approaches in terms of extent of degradation of CBZ
Figure 9 Intermediate analysis using LC-MS
Table 5: Effect of inlet pressure on extent of degradation of CBZ and kinetic rate constant Pressure
Extent of degradation (%)
K× 103 (min-1)
3
10.4
0.6
4
16.5
1.3
5
16.03
1.4
Table 6: Effect of pH on extent of degradation of CBZ and kinetic rate constant pH
Extent of degradation (%)
K× 103 (min-1)
3
31.8
3.1
4
38.7
3.8
5
20.4
1.9
6
22.4
2.1
11
19.0
1.9
Table 7: Comparison of different combined processes in terms of synergistic index Extent of degradation
K× 103 (min-1)
Synergistic Index
Scheme (%) Only HC
38.7
3.8
-
Only UV
18.0
1.3
-
Only H2O2
29.4
2.2
-
Only O3
49.1
4.8
-
HC+ UV
52.9
4.9
0.9
HC+ H2O2
58.3
6.1
1.01
HC + O3
91.4
19.1
2.2
HC+ H2O2 + O3
100
34.7
3.2
Table 8: Comparison of different processes in terms of cavitational yield and total treatment cost Total Cavitation Degradation Yield×105
Scheme (%)
(mg/J)
Energy required
cost
Total Additive
related
to
Treatment cost
power
(kWh)
cost (Rs./L)
(Rs./L)
(Rs./L)
Only HC
38.7
9.15
0.0303
0.27
-
0.27
HC+ UV
52.9
7.45
0.0372
0.33
-
0.33
HC+ H2O2
58.3
13.8
0.0201
0.18
0.13
0.31
HC + O3
91.4
15
0.01857
0.16
-
0.16
HC+ H2O2 + O3
100
15.7
0.01777
0.16
0.13
0.29
HIGHLIGHTS: Degradation of Carbamazepine using combined processes based on hydrodynamic cavitation
Understanding into effect of operating pressure and pH of wastewater
Comparison of different treatment approaches at large scale operation in terms of cavitational yield and economics Combined process gives higher extent of degradation resulting into synergistic effects Optimized approach involving hydrodynamic cavitation, ozone and hydrogen peroxide is the best