Biosorption of Cr(VI) and Ni(II) onto Hydrilla verticillata dried biomass

Ecological Engineering 73 (2014) 713–723

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Biosorption of Cr(VI) and Ni(II) onto Hydrilla verticillata dried biomass Ashutosh Mishra a , Brahma Dutt Tripathi b, *, Ashwani Kumar Rai b a b

Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi 221005, India Department of Botany, Banaras Hindu University, Varanasi 221005, India

A R T I C L E I N F O

A B S T R A C T

Article history: Received 5 May 2014 Received in revised form 10 August 2014 Accepted 7 September 2014 Available online xxx

In the present study Hydrilla verticillata dried biomass was modified by Fenton reagent and its technical feasibility for removal of Cr6+ and Ni2+ ions from wastewater were investigated. Fenton modification process was optimized by varying pH, biosorbent dose, contact time, and Fe2+/H2O2 ratio. For Fenton modification process the optimum values of pH, biosorbent dose, contact time, and Fe2+/H2O2 ratio were 4, 70 mg L
1, 70 min and 0.04 w/w, respectively. The modified biosorbent was characterized by using SEM-EDX, FT-IR and Malvern particle size analyzer. SEM-EDX analysis revealed the enhancement in weight percent of Cr6+ (47.38%) and Ni2+ (41.26%) ions on the surface of Fenton modified dried biomass of Hydrilla verticillata (FMB) after biosorption. Maximum biosorption of Cr6+ and Ni2+ ions were observed to be 29.43 and 48.72 mg g
1 for raw biomass and 107.64 and 106.12 mg g
1 for Fenton modified biomass respectively. Experimental data were modeled using single and multi-component isotherm models. For single-metal component, the Freundlich isotherm model fits the data better than the Langmuir isotherm model. In case of binary-metal solution the experimental data show good agreement with multicomponent Freundlich isotherm model. The enhancement in the overall biosorption capacity after the Fenton modification was observed which follows the sequence: Cr6+ > Ni2+. The biosorption process followed the pseudo-second order kinetics. The equilibrium data suggest the involvement of chemisorption mechanism. Positive values of enthalpy and negative values of Gibbs free energy obtained during thermodynamic study revealed that the biosorption process was endothermic and spontaneous in nature. ã 2014 Elsevier B.V. All rights reserved.

Key words: Biosorption Chromium Fenton Modification Hydrilla verticillata Nickel SEM-EDX

1. Introduction The adverse effect of metals on the environment and especially on human health has become a very important matter of concern in the third world countries. Due to their persistent nature these metals do not eliminate easily and gets accumulated in the different components of the environment (Sasmaz and Obek, 2009), causing serious threat to natural ecosystems (DeForest et al., 2007). Some of these metals viz. chromium (Cr6+) and nickel (Ni2+) are excessively discharged into the environment by various industrial processes (leather tanning, electroplating, steel manufacturing, pulp processing, wood preservation etc.) and are identified as carcinogenic to human beings (Fu and Wang, 2011). The industrial effluent maximum permissible discharge limit of Cr6+ and Ni2+ into inland surface water is 0.1 and 3.0 mg L
1, respectively (Congeevaram et al., 2007; BIS, 1993). Chromium more than its permissible limit

* Corresponding author. Tel.: +91 9415225011; fax: +91 5422369139. E-mail addresses: [email protected] (A. Mishra), [email protected] (B.D. Tripathi), [email protected] (A.K. Rai). http://dx.doi.org/10.1016/j.ecoleng.2014.09.057 0925-8574/ ã 2014 Elsevier B.V. All rights reserved.

adversely affect human health by causing skin diseases, lung carcinoma etc. (Khezami and Capart, 2005). Nickel more than its maximum contaminant level poses severe kidney and lung disorders apart from pulmonary fibrosis, skin dermatitis, and gastrointestinal suffering (Borba et al., 2006). Numerous techniques are reported for the elimination of metals from wastewater such as chemical precipitation (Esalah et al., 2000), ion exchange (Cardoso et al., 2004), reverse osmosis (Mohsen-Nia et al., 2007), solvent extraction (Li et al., 2008), membrane technologies (Janson et al., 1982), electrochemical treatment (Lai and Lin, 2003), coagulation and flotation (Yuan et al., 2008), etc. However, use of these techniques are occasionally restricted owing to their technical or economical limitations (Puranik and Paknikar, 1999). Therefore, it becomes necessary to develop simple, cost effective, and ecofriendly technology for the removal of metal ions from wastewater. In recent times, removal of metals using biosorption technique has gained significant interest because of their high effectiveness, low cost, and simplicity (Vijayaraghavan et al., 2006). Extensive review of available literatures suggested that number of low cost natural biosorbents or adsorbents such as Coriolus versicolor (Bhatti and Amin, 2013), Citrus paradise pulp waste (Ishfaq et al., 2013),

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Eucalyptus citriodora distillation sludge (Bhatti and Hamid, 2014), Pine needles (Dakiky et al., 2002); Alternanthera philoxeroides biomass (Wang and Qin, 2006), sawdust activated carbon (Karthikeyen et al., 2005); Ulva sp. and Gracillaria sp. (Sheng et al., 2004), coconut shell carbon (Babel and Kurniawan, 2000), dried Chlorella vulgaris (Aksu and Acikel, 1999); clinoptilolite and chabazite (Ouki and Kavannagh, 1999), Sargassum sp. (Kratochvil et al., 1998) etc., have been utilized for the removal of toxic metal ions from wastewater. To enhance the removal efficiency and to reduce organic contents of low cost natural biosorbents, different modification techniques have been utilized by previous researchers (Bhatti et al., 2013; Kausara et al., 2013; Argun and Dursun, 2008; Horsfall et al., 2006; Taty-Costodes et al., 2003). Among them, the Fenton’s oxidation process has attracted considerable interest. Fenton’s reagent is a mixture of ferrous iron and hydrogen peroxide (H2O2/Fe2+) which generates highly reactive hydroxyl radical, capable of degrading wide range of organic and inorganic pollutants (Pignatello et al., 2006; San Sebastian et al., 2003). The Fenton process also has numerous significant advantages for instance reagents are economical, short reaction time among all advanced oxidation processes (Pouran et al., 2013), iron is highly abundant and non-toxic, hydrogen peroxide is easy to handle and environmentally benign (Venny Gan and Ng, 2012; Valderrama et al., 2009; Ferrarese et al., 2008; Munter, 2001), high efficiency of mineralization facilitates the conversion of organic pollutants into non-toxic carbon dioxide (Bokare and Choi, 2014; Nidheesh et al., 2013) and the overall procedure is easy to execute and control (Miretzky and Munoz, 2011; Argun and Dursun, 2008). Hydrogen peroxide used in the Fenton process would cause no environmental threat because application of diluted and stabilized hydrogen peroxide (5–20%) not only promotes a safer working environment during exothermic in situ application of Fenton reaction but also results in enhanced treatment efficiency throughout the in situ remediation compared to concentrated H2O2 (30–35% commercial grade) (Kakarla et al., 2002; Venny Gan and Ng, 2012). In the present investigation Hydrilla verticillata, a submerged invasive aquatic plant was utilized as a source of biomass because of its wide spread availability and very fast growth rate (2.5 centimeters per day) (Nigam et al., 2013). Numerous investigations on biosorption of different metals utilizing H. verticillata suggest that these aquatic plants possess hydroxyl groups in their cellulosic matrix (Li et al., 2013; Naveen et al., 2011; Huang et al., 2010). Modification of biosorbent using Fenton’s reagent can oxidize these hydroxyl groups of cellulose into carboxyl groups by creating a weak cationic ion exchanger (Shukla and Pai, 2005), which ultimately could enhance the metal removal efficiency up to many folds. Therefore, the aim of the present research study was to investigate the potential of Fenton modified dried biomass of H. verticillata (FMB) for the removal of Cr6+ and Ni2+ ions from aqueous solutions as well as from wastewater. Various mathematical models related to biosorption isotherm, kinetics, and thermodynamic parameters were utilized for the better perception of the overall biosorption process. Moreover, these models were

also used to compare the biosorption capacity of FMB with raw H. verticillata dried biomass (RB). 2. Materials and methods 2.1. Study area Present research work was performed in the city of Varanasi (24 350 N to 25 300 N and 82 150 E to 83 300 E) situated in the Gangetic plain of India. In the city, three sewage treatment plants (STP) viz. Dinapur STP (1986), Bhagwanpur STP (1988) and Diesel Locomotive Works STP (1989) with treatment capacities of 80, 9.8 and 12 million liters per day million litres per day (MLD) respectively were commissioned under the Ganga Action Plan (GAP) by the Government of India. These STPs provide only primary and secondary treatment of wastewater functioning on Activated Sludge Process (ASP) technology. There is no provision for the advance treatment of wastewater. It is estimated that in the city approximately 300 MLD wastewater (industrial effluent mixed with city sewage) is generated, out of which approximately 101.8 MLD is treated and rest is being discharged directly or indirectly into the river Ganga (Tripathi et al., 2011) that serves the population of northern India. This insufficient discharge of wastewater ultimately aggravates the problems associated with river pollution (Dyer et al., 2003). Moreover, these secondary treated effluents laden with several metal ions are also used for the irrigation of nearby crop fields at Varanasi. This unsuitable irrigation practice results in the accumulation of metals in different edible parts of the plant ultimately causing serious threat to human health (Rai and Tripathi, 2008). Therefore, present study was conducted to suggest an economic as well as effective tertiary treatment process using the Fenton modified biosorption technology. 2.2. Wastewater sampling and analysis Representative wastewater samples were collected from the effluent channel of Bhagwanpur STP in PTFE bottles (pre-washed with acid), preserved and transported to the pollution ecology research laboratory in ice boxes. Concentration of metal ions in samples were analyzed by using standard protocols (APHA, 2012). Data presented in Table 1 revealed that the concentration of Cr6+ and Ni2+ ions in wastewater samples were higher as compared to their maximum effluent discharge standards (EPA, 2004; BIS, 1993). 2.3. Biosorbent preparation The live biomass of H. verticillata was collected from the nearby pond of the university. The biomass was washed under the running tap water followed by ultra pure water (Milli-Q) to remove sediments and particulate matter. Further, the biomass was dried in sunlight for two days followed by oven drying at 70  C for 48 h. After drying, the biomass was grounded and sieved through mesh to get particles below 1 mm in size. The dried biomass of

Table 1 Concentration of Cr6+ and Ni2+ ions in wastewater samples with their maximum effluent discharge standards. Metal ions

Concentration in wastewater samples (mg L
1)

a

EPA (mg L
1)

b BIS specification is 10500 (mg L
1)

Cr6+ Ni2+

1.2 0.67

0.05 0.20

0.10 3.00

a b

Environmental Protection Agency (EPA) 2004, USA. Bureau of Indian Standard Specification (BIS), IS 1993, India.

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H. verticillata (biosorbent) was further subjected to Fenton modification process. 2.4. Fenton modification of biosorbent Fenton modification of biosorbent was done by the method as described elsewhere (Argun and Dursun, 2008). After determining the optimum Fe2+/H2O2 ratio (0.04 w/w), pH 4, temperature (room temperature), contact time (70 min) and biosorbent dose (70 g L
1), 20 g of dried biomass of H. verticillata was added into 500 mL Erlenmeyer flask containing 250 mL Fenton’s reagents and agitated on rotatory shaker at 250 rpm for 60 min. After agitation the solution was filtered and the modified biosorbent was washed with ultra pure water followed by oven drying at 80  C for 2 h. 2.5. Metal solutions Stock solutions (1000 mg L
1) of Cr6+ and Ni2+ ions were prepared by dissolving known quantity of K2Cr2O7 and NiCl26H2O (analytical reagent grade) respectively in ultra pure Milli-Q water. Standard solutions of Cr6+ and Ni2+ ions with different concentrations were finally prepared by diluting the stock solutions. 0.1 M NaOH and HNO3 were used for the pH adjustment.

715

blanks were also used as controls. The quantity of Cr6+ and Ni2+ ions biosorbed by RB and FMB was computed by subsequent mass balance expression (Davis et al., 2000):
V S Ci
Cf (1) Q MA ¼ W DB where, QMA is the quantity of metal ions biosorbed (mg g
1), VS is the volume of solution (L), Ci and Cf are initial and final metal ions concentration (mg L
1) and WDB is the weight of dried biomass (g). The removal efficiency (REM) of Cr6+ and Ni2+ ions by RB and FMB was calculated by using the following equation (Miretzky and Munoz, 2011): REM ¼ ðCi
Cf =CfÞ  100

(2)

2.6.2. Performance of batch reactor in treating secondary effluent In order to evaluate the efficiency of batch reactor in treating secondary effluent containing Cr6+ and Ni2+ ions, the wastewater samples were used instead of metal solutions under same experimental conditions. The concentration of Cr6+ and Ni2+ ions in wastewater samples are presented in Table 1. 3. Results and discussion

2.6. Experimental design

3.1. Characterization of biosorbent

2.6.1. Biosorption batch experiment Batch experiments were executed in 250 mL Erlenmeyer flask, containing 100 mL solution of metal ions at pH values ranging from 1 to 7. Required amount of RB and FMB were then added separately to the Erlenmeyer flask and agitated for 60 min at 250 rpm. Preliminary experiments showed that the time period of 60 min was enough to achieve equilibrium. After agitation the metalbiosorbent solution was further subjected to centrifugation for 15 min at 2000 rpm and finally filtered with the help of cellulose acetate membrane (0.45 mm). Initial and final concentrations of Cr6+ ions were analyzed by diphenylcarbazide method, using an UV/visible spectrophotometer at 540 nm. Similarly, Ni2+ ions were analyzed by atomic absorption spectrophotometer at 232 nm following standard protocols (APHA, 2012). In order to avoid errors in measurement all experiments were carried out thrice and their mean values were used for calculations. Under the same experimental conditions, metal ions-free and dried biomass-free

The average particle size and specific surface area of the FMB was found to be 49.7 mm and 33.33 m2 g
1 respectively, analyzed using Malvern Matersizer 2000. The FT-IR spectra of FMB before and after biosorption were obtained using PerkinElmer Spectrum Version 10.03.05 (Fig. 1a and b). The spectral band at 3421.24 cm
1 shows the stretching of O—H and N—H, 2926.17 cm
1 indicates the asymmetric stretching vibration of CH2, the peak at 1637.35 cm
1 correspond to stretching vibration of C¼O, the peaks at 1420.29 cm
1 and 1322.04 cm
1 correspond to stretching of C—O and carboxyl group respectively. Shift in different peaks were observed after the biosorption process which suggests the combination of functional groups and metal ions (Baral et al., 2009; Huang et al., 2010). SEM (scanning electron microscopy) coupled with EDX (energy dispersive X-Ray spectroscopy) (FEI QUANTA 200 F) was used to analysis the fresh FMB and metal ions (Cr6+ and Ni2+) loaded FMB to assess the alteration in surface morphology and elemental composition before and after the biosorption

Fig. 1. FT-IR spectra of FMB (a) before biosorption (b) after biosorption.

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Fig. 2. SEM-EDX image of FMB (a) before biosorption (b) after biosorption.

process (Fig. 2a and b). It can be observed from the figures (Fig. 2a and b) that the surface was rough before biosorption process which becomes smooth after the process. The weight percent of Cr6+ and Ni2+ ions on FMB surface before biosorptionwas observed to be 0.43% and 0.22% respectively. But after the biosorption considerable enhancement in the weight percent of Cr6+ (47.38%) and Ni2+ (41.26%) ions were found, confirming the biosorption of Cr6+ and Ni2+ ions on the surface of FMB (Baral et al., 2009). Furthermore, the decline in the peaks of sodium and potassium indicates (Fig. 2a and b) that the biosorption process might be due to ion-exchange mechanism (Huang et al., 2010). 3.2. Effect of Fenton oxidation process parameters on modification of biosorbent For the Fenton modification process we have considered the removal of Cr6+ ions only and results were applied in all the

following batch experiments. The influence of pH on the FMB was assessed by the efficiency of Cr6+ ion removal (Fig. 3a). The maximum biosorption of Cr6+ ion was attained at pH value 4 (Fig. 3a). At pH values less than 4, the excess production of H+ ion suppresses the hydroxyl radical formation. On the other hand, generation of metal hydroxides at pH values greater than 4, hinder the whole catalytic process suppressing the formation of hydroxyl radical (Miretzky and Munoz, 2011). Thus it can be concluded that for modification process the optimum pH value was 4. Since there was no significant effect on the removal of Cr6+ ions with rise in temperature from 20  C to 70  C (Fig. 3b), so room temperature was selected as an optimum temperature for the modification process. The optimum biosorbent dose for modification process was observed to be 70 g L
1 (Fig. 3c). Also Fe2+/H2O2 ratio of 0.04 (w/w) was found to be optimum for the process. Fig. 3d suggests that 70 min contact time was optimum for the reaction.

A. Mishra et al. / Ecological Engineering 73 (2014) 713–723

a

100

c 80

90

70

80

% Removal

60

% Removal

717

50 40 30

70 60 50 40

20

30

10 0

20 0

2

4

6

8

0

20

40

60

pH

Dose (g

100

120

140

L-1)

d

100 95

100

90

90

85

80

80

% Removal

% Removal

b

80

75 70 65

70 60 50

60

40

55

30

50

20 0

20

40

60

80

Temperature OC

0

20

40

60

80

100

120

Time (minutes)

Fig. 3. Effect of (a) pH (b) temperature (c) dose (d) contact time on the Fenton modification process.

3.3. Biosorption batch studies 3.3.1. Effect of initial metal solution pH on biosorption Previous researches on Cr6+ and Ni2+ biosorption demonstrated that pH is an important factor which influences the overall biosorption process (Gupta et al., 2010; Chojnacka et al., 2005). Therefore, the effect of initial metal solution pH on the biosorption process using FMB was examined. In order to examine the effect, the pH range was varied from 1 to 7. To avoid the precipitation of Cr6+ and Ni2+ ions, solution pH was not increased beyond 7 (Hawari and Mulligan, 2006; Gupta et al., 2010). The optimum biosorption capacity was observed at pH 4.5 and 5.5 for Cr6+ and Ni2+ ions, respectively (Fig. 4a). Sharp decrease in biosorption capacity was observed below pH 2.5. The plausible explanation for this behavior might be the development of repulsive force due to the protonation of active binding sites which restrict the binding of metal ions under acidic condition (Hawari and Mulligan, 2006; Aldor et al., 1995). 3.3.2. Effect of initial metal ion concentration on biosorption The effect of different initial concentrations of Cr6+ and Ni2+ ions on biosorption by FMB were examined at the most suitable experimental conditions. The results were shown in Fig. 4b. The equilibrium Cr6+ and Ni2+ uptake by FMB increases from 6.26 to

14.09 mg g–1 and 4.32 to 11.43mg g–1 respectively, as the metal ions concentration increases (Manohar et al., 2002) but the biosorption percentage of Cr6+ and Ni2+ ions decreases from 89.34% to 61.57% and 83.64% to 56.14% respectively. The increase in metal uptake could be attributed to the differences in the concentration gradient across the two phases. Decrease in biosorption percentage might be due to lack of availability of more active sites and sufficient surface area to hold more metal ions present in the solution (Gupta et al., 2010; Kumar et al., 2006). 3.3.3. Effect of contact time on biosorption Batch experiments were performed to find out the effect of contact time on the biosorption of Cr6+ and Ni2+ ions (Fig. 4c). Throughout the experiment the other parameters viz. pH (4.5 and  5.5), temperature (30 C), initial metal concentration (10 mg L
1) and biosorbent dose (2.5 g and 1.9 g) were kept constant. The process was very fast initially for a period of 20 min thereafter the process becomes slow and reached the equilibrium at 80 min (Cr6+) and 120 min (Ni2+ ions). Very fast process of biosorption initially could be attributed to the availability of more free surface active sites and involvement of mechanisms like ion-exchange or physical biosorption at the FMB surface (Ronda et al., 2013). Once these sites are blocked, the intra-particle diffusion of biosorbate takes place which might be responsible for the slower biosorption

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120 90 80

Cr

100

Cr

60

% Removal

% Removal

70 Ni

50 40

80

Ni

60

40

30 20

20

10 0

0 0

2

4

6

0

8

50

pH

150

200

250

Time (minutes)

c

d 50

85

45

80

40

75

35

70

30

95 Cr %

90

% Removal

90

Metal Uptake (mg g-1)

% Biosorption

100

Ni %

85 Ni 80

65

25

60

20

55

15

50

10

45

5

65

0

60

40 0

50

Cr Uptake

Cr

75 70

Ni Uptake

100

0

1

Concentration (mg L-1)

2

3

4

5

Biosorbent Dose (g)

Fig. 4. Effect of (a) pH (b) initial metal ion concentration (c) time (d) biosorbent dose on the removal of metal ions.

process at the later stage (Baral et al., 2009; Karthikeyen et al., 2005). Moreover, involvement of mechanisms like micro-precipitation or complexation might also be responsible for slower phase. Similar results (two stage biosorption kinetics) were also reported by other researchers (Nordin et al., 2012; Sharain-Liew et al., 2011; Garcia-Rosales and Colin-Cruz, 2010).

2007). The optimum biosorbent dose was found to be 2.5 g and 1.9 g for Cr6+ and Ni2+ ions respectively. With further increase in biosorbent dose beyond the optimum level the removal efficiency of metal ions remained almost constant, this may be due to the reaching of equilibrium state at given experimental conditions (Baral et al., 2009).

3.3.4. Effect of biosorbent dose The effect of varying biosorbent dosage on the removal efficiency of Cr6+ and Ni2+ ions are shown in Fig. 4d. The biosorption of metal ions increased with increasing biosorbent dosage, this can be attributed to the rise in overall surface area due to increase in more active sites on the biosorbent (Ahmel et al.,

3.4. Biosorption isotherm studies 3.4.1. Models for single-component systems The equilibrium biosorption data obtained from the batch study were modeled using Langmuir (1916) and Freundlich (1906) isotherm models. Langmuir model is expressed by equation as

Table 2 Langmuir and Freundlich isotherm constants and correlation coefficients of isotherm models. Metal ions

6+

Cr

Ni2+

Treatment

Langmuir

Freundlich 2

Qmax

b

r

Kf

1/N

r2

Raw biomass Fenton modified biomass

29.43 107.64

0.227 0.531

0.879 0.989

19.27 24.52

0.597 0.922

0.948 0.998

Raw biomass Fenton modified biomass

48.72 106.12

0.244 0.574

0.882 0.996

16.35 22.18

0.604 0.883

0.896 0.999

A. Mishra et al. / Ecological Engineering 73 (2014) 713–723

lnQ e ¼ lnK f þ

follows: Qe ¼

Q max  b  C e 1 þ b  Ce

(3)
1

where Qe is the amount of metal ions biosorbed (mg g ), Qmax is the maximum biosorption capacity (mg g
1), Ce is the metal ions concentration in the solution at equilibrium (mg L
1) and b is the constant related to the energy or net enthalpy of biosorption (L mg
1). In order to fit the experimental data, the linear form of Langmuir expression was used which is described by the equation given as follows: 1 1 1 1 þ ¼ þ Q e Q max Q max  b C e

(4)

The Langmuir isotherm fitting parameters and correlation coefficient (r2) values for Cr6+ and Ni2+ ions biosorption onto RB and FMB are shown in Table 2. Langmuir Qmax values of Cr6+ and Ni2+ ions were 29.43 and 48.72 mg g
1 for RB and 107.64 and 106.12 mg g
1 for FMB respectively. This clearly indicates that the Fenton modification of the biomass significantly increased the biosorption capacity. Modification of biomass with Fenton’s reagent results in the oxidation of hydroxyl groups of cellulose and hemicellulose, which ultimately generates weak cationic ionic exchanger. This oxidation of the cellulosic component might be responsible for its degradation finally leading to chain scission. Similar studies were reported by other researchers also (Miretzky and Munoz, 2011; Shukla and Pai, 2005). The study conducted by Shukla and Pai (2005) indicates that modification of jute fibers by oxidation with hydrogen peroxide ultimately enhances the adsorbent efficiency in removing Cu2+, Ni2+ and Zn2+ ions from their aqueous solutions than the unmodified adsorbent. The metal ion uptake values of Cu2+, Ni2+ and Zn2+ ions for oxidized jute fibers were 7.73, 5.57 and 8.02 mg g
1, as against 4.23, 3.37 and 3.55 mg g
1 for unmodified jute fibers. Similarly, the research study of Miretzky and Munoz (2011) showed that the activation of Eichhornia crassipes biomass by Fenton treatment increase the adsorption efficiency by 78% for Zn2+ removal from contaminated water. Freundlich model is expressed by the equation: 1 n

Q e ¼ K f  Ce

(5)

where Kf (mg g
1) is the Freundlich constant or biosorption capacity and n denotes the biosorption intensity. In order to fit the experimental data, the linearized Freundlich expression was utilized which is described by the equation given as follows:

719

1  lnC e n

(6)

The increased Kf value after the Fenton modification process indicates the enhancement in biosorption capacity (Table 2). The value of 1/n less than 1 shows the favorable biosorption. Both the biosorption isotherm models fit the experimental data reasonably well. However, the Freundlich isotherm model fits the data slightly better than the Langmuir isotherm model. The biosorption capacity of Cr6+ and Ni2+ ions were in agreement with earlier research studies using Rosa damascena Phytomass (Iqbal et al., 2013), Termitomyces clypeatus (Khowala, 2012), Pleurotus ostreatus spent biomass (Carol et al., 2012), immobilized Cunninghamella elegans (Abdel-Razek, 2011), Chlorella species (Kanchana et al., 2011), Alternanthera philoxeroides biomass (Wang and Qin, 2006), marine algal biomass (Sheng et al., 2004). Comparison of raw and Fenton modified H. verticillata dried biomass with other adsorbents or biosorbents for Cr6+ and Ni2+ ions removal were presented in Table 3. From the table it can be concluded that the FMB is much more efficient in removing Cr6+ and Ni2+ ions from wastewater. 3.4.2. Models for multi-component systems When numerous metal ions are present, there might be interference and competition between different metal ions for surface active sites. Thus single metal ion biosorption isotherm models are inapplicable in that case. As a consequence of the non applicability of single metal ion biosorption isotherm models for multi-component systems, the experimental data was further analyzed using subsequent multi-component isotherm models viz. modified Langmuir model (McKay and Al Duri, 1989) and Freundlich multi-component model (Fritz and Schluender, 1974). The modified Langmuir isotherms for binary metal ion solution can be expressed as follows: Q e;1 ¼

Q 01  b1  C 1 1 þ b1  C 1 þ b2  C 2

(7)

Q e;2 ¼

Q 02  b2  C 2 1 þ b1  C 1 þ b2  C 2

(8)

where C1and C2 are the concentrations of Cr6+ and Ni2+ in the solution at equilibrium, Qe,1 and Qe,2 are the uptakes of Cr6+ and Ni2+in the binary metal solution, b1 and b2 are the Langmuir biosorption constants of Cr6+ and Ni2+in the single component systems, Q10 and Q20 are the Langmuir biosorption capacities of Cr6 + and Ni2+ in the single component system. The multi-component Freundlich isotherms can be expressed as:

Table 3 Comparison of raw biomass (RB) and Fenton modified Hydrilla verticillata dried biomass (FMB) with other biosorbent for Cr6+ and Ni2+ ions removal. Biosorbent

Biosorption capacity (mg g
1) 6+

Sargassum sp. Ulva sp. Gracillaria sp. Clinoptilolite Chabazite Sawdust activated carbon Spirogyra Coconut shell carbon Alternanthera philoxeroides biomass Pine needles Dried Chlorella vulgaris RB FMB

References 2+

Cr

Ni

40 – – – – 44.05 14.7 10.88 17.17 21.5 27.8 29.43 107.64

35.3 16.8 16.2 0.9 4.5 – – – 9.73 – – 48.72 106.12

(Kratochvil et al., 1998; Sheng et al., 2004) (Sheng et al., 2004) (Sheng et al., 2004) (Ouki and Kavannagh, 1999) (Ouki and Kavannagh, 1999) (Karthikeyen et al., 2005) (Kratochvil and Pimentel, 1998) (Babel and Kurniawan, 2000) (Wang and Qin, 2006) (Dakiky et al., 2002) (Aksu and Acikel, 1999) Present study Present study

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Table 4 Modified Langmuir and Freundlich multi-component isotherm comparisons for raw biomass and Fenton modified biomass. Metal ions

Treatment

Metal concerntration (mg L-1)

Qe (mg g-1)

Modified Langmuir model -1

6+

Cr

Raw biomass

Fenton modified biomass

Ni2+

Raw biomass

Fenton modified biomass

Freundlich multi-component model

Qe(mg g ) predicted

Qe (mg g-1) predicted

20 40 60 80 100 20 40 60 80 100

47 49 52 53 57 84 87 89 90 93

36 38 40 46 47 61 65 67 72 74

47 48 50 54 60 87 90 88 90 96

20 40 60 80 100 20 40 60 80 100

34 35 38 41 44 73 79 81 84 86

23 26 27 29 32 59 62 68 69 72

31 34 39 44 43 76 78 85 87 86

C1 1 ¼  b1
a12 C2 C2

(9)

C2 1 ¼  b2
a21 C1 C2

(10)

where C1 and C2 are the concentrations of Cr6+ and Ni2+ in the solution at equilibrium, a12 and a21 are the competition coefficients. The result presented in Table 4 showed that the modified Langmuir isotherm model could not be applied for the prediction of biosorption isotherm because of differences in the experimental and predicted values of Cr6+ and Ni2+ uptake over the range of concentrations studied using RB and FMB both. This might be due to the supposition of entirely competitive biosorption incorporated in the modified Langmuir isotherm model whereas the competition of Cr6+ and Ni2+ ions for surface active sites on RB and FMB could have been very low (Baig et al., 2009). The results of multi-component Freundlich isotherm model are shown in Table 4. The experimental data for Cr6+ and Ni2+ ions show good agreement with multi-component Freundlich isotherm model predictions over the range of concentrations studied using RB and FMB both. Furthermore, the biosorption capacities of both RB and FMB for

binary-metal solution were relatively lower in comparison to the single metal solution. This may be due to differences in ionic charge, radii, and electrode potential of different metals which affects the overall binary-metal ions biosorption (Saygideger et al., 2005). 3.5. Biosorption kinetic studies Two different biosorption kinetic models viz. pseudo-first order and pseudo-second order models were employed to the experimentally obtained biosorption data. The biosorption kinetic studies were performed separately for RB and FMB. The pseudofirst order (Lagergren, 1898) rate equation which is expressed as follows: logðQ e
Q t Þ ¼ logQ e


K1  t 2:303

(11)

Eq. (11) was used to fit the experimental data, where Qe (mg g
1) and Qt (mg g
1) are the amount of metal ions biosorbed at equilibrium and at time t respectively. k1 (min
1) is the biosorption rate constant. The values of k1 and Qe calculated (cal.) can be obtained from the slope and intercept of the plot between log (Qe –

Table 5 Fitting parameters for pseudo-first order and pseudo second-order along with their correlation coefficients (r2) values. Metal ions

Cr6+

Treatment

Raw biomass

Fenton modified biomass

Ni2+

Raw biomass

Fenton modified biomass

Temperature(K)

Qe (mg g
1) experimental

Pseudo-first order model

Pseudo second order model

k 1(min
1)

Qe(cal.) (mg g
1)

r

2

k2 (g mg
1 min
1)

Qe(cal.) (mg g
1)

r

2

293 303 313 293 303 313

46 44 42 79 76 72

0.1033 0.1021 0.0895 0.0824 0.0578 0.0532

30 29 27 48 45 46

0.812 0.789 0.767 0.856 0.862 0.859

0.0758 0.0834 0.0862 0.0710 0.0893 0.0968

45 41 38 79 71 75

0.998 0.977 0.992 0.999 0.986 0.984

293 303 313 293 303 313

38 33 32 60 58 57

0.0539 0.0492 0.0736 0.0543 0.0527 0.0483

26 28 24 46 44 44

0.726 0.744 0.725 0.819 0.834 0.828

0.0872 0.0927 0.0963 0.0875 0.0894 0.0912

38 33 32 60 58 55

0.979 0.994 0.997 0.998 0.996 0.999

A. Mishra et al. / Ecological Engineering 73 (2014) 713–723

Qt) and t. The biosorption rate constant (k1) and their corresponding correlation coefficient (r2) values are given in the Table 5. Owing to differences in calculated values of Qe (cal.) and experimental values of Qe, it can be concluded that the pseudo-first order model is not appropriate to predict the biosorption reaction kinetics in this case. Therefore, the experimental data was further analyzed using pseudo-second order model. The linear form of the pseudo-second order model is expressed as (Ho and McKay, 1999): t t 1 ¼ þ Q t Q e K 2  Q 2e

(12)

where Qe (mg g
1) and Qt (mg g
1) are the amount of metal ions biosorbed at equilibrium and at time t respectively. k2 (g mg
1 min
1) is the biosorption rate constant and t is the contact time (min). The values of k2 and Qe (cal.) can be obtained from the slope and intercept of the plot between t / Qt and t. The calculated values of Qe (cal.) obtained from the plot matches with the experimental values of Qe (Table 5). Moreover, the correlation coefficient (r2) values were higher for Cr6+ and Ni2+ions. Thus it can be concluded that the pseudo-second order rate equation fits the experimental data relatively better than the pseudo-first order rate equation, supporting the postulation that the chemisorption may be the rate-limiting step in this case.

721

Table 6 Thermodynamic parameter for biosorption of Cr6+ and Ni2+ ions. Metal ions

Temperature (K)

Ko

DG0 (KJ mol
1)

Cr6+

293 303 313 293 303 313

39 41 42 31 33 36


2.59
4.36
6.44
1.82
3.27
5.94

Ni2+

Table 7 Percentage removals of Cr6+ and Ni2+ ions from wastewater using RB and FMB. Metal ions

Concentration (mg L
1) % Removal after raw before biosorption biomass biosorption

% Removal after FMB biosorption

Cr6+ Ni2+

1.2 0.67

94 % 85 %

72 % 67 %

secondary effluent samples instead of metal ion solutions under identical experimental conditions. Significant increase in removal efficiency of Cr6+ (from 72% to 94%) and Ni2+ (from 67% to 85%) ions were observed after the modification of biosorbent (Table 7).

3.6. Thermodynamic studies 4. Conclusions For thermodynamic studies batch experiments were performed at 293, 303 and 313 K temperatures using only FMB. To assess the feasibility of the process, different thermodynamic parameters were estimated using the equation given as follows:

DG0 ¼
RTlnK o

(13)

where DG is standard free energy change, R is the universal gas constant (8.314 Jmol
1 K
1), T is the absolute temperature, and Ko is the thermodynamic constant. Ko values can be determined by plotting a graph between ln Qe/Ce versus Qe at different temperatures, where Qe the amount of metal ions biosorbed and Ce is the metal ions concentration in the solution at equilibrium.The change in enthalpy (4H0) and entropy (4S0) were determined by the following equation: o

lnK o ¼

DSo R




DHo

(14)

RT

The change in enthalpy (4H ) and entropy (4S ) were estimated from the slope and intercept of the plot between ln Ko versus 1/T. With rise in temperature from 293 K to 313 K the value of Gibbs free energy decreases from
2.59 to
6.44 and
1.82 to
5.94 for Cr6+ and Ni2+ ions, respectively (Table 6). This might be due to increase in the degree of protonation of carboxylic and amine groups on the surface of FMB with rise in temperature (Donais et al., 1999; Biesuz et al., 1997). The change in enthalpy (4Ho) and entropy (4So) were found to be 63.52 and 58.14 and
0.324 and
0.253 for Cr6+ and Ni2 + ions, respectively. The positive values of 4Ho suggest that the process is endothermic in nature whereas the negative values of 4So indicate the decline in degree of freedom of biosorbed metal ions (Kadirvelu et al., 2001). Thus it can be concluded that the biosorption process using FMB was spontaneous, chemically governed and endothermic in nature. Similar findings were also reported by the other researchers (Baral et al., 2009; Wang and Qin, 2006). o

o

3.7. Performance of batch reactor in treating secondary effluent In order to assess the performance of batch reactor in treating secondary effluent, the batch studies were also executed by using

Fenton modification technique was used to enhance the biosorption capacity of H. verticillata dried biomass. For Fenton modification process at room temperature the optimum values of pH, biosorbent dose, contact time, and Fe2+/H2O2 ratio were 4, 70 mg L
1, 70 min and 0.04 w/w, respectively. Biosorption capacity for Cr6+ and Ni2+ ions were 29.43 and 48.72 mg g
1 for RB and 107.64 and 106.12 mg g
1 for FMB, respectively. Results revealed that for single-metal ion solution the Freundlich isotherm model fits the data better than the Langmuir isotherm model. In case of binary-metal ion solution the experimental data for Cr6+ and Ni2+ ions show good agreement with multi-component Freundlich model predictions over the range of concentrations studied using RB and FMB both. For multi-metal solution the biosorption capacity was found to be relatively lower than the single-metal solution. SEM-EDX analysis revealed the enhancement in the weight percent of Cr6+ (47.38%) and Ni2+ (41.26%) ions on the surface of FMB after the biosorption. The biosorption process followed the pseudo-second order kinetics suggesting that the chemisorption may be the rate-limiting step in this case. Thermodynamic study showed that the biosorption process was spontaneous and endothermic in nature. Performance of batch reactor in treating secondary effluent using FMB showed significant reduction in Cr6+ and Ni2+ ions concentration after the biosorption process. Thus it can be concluded that the FMB could be a better option to remove Cr6+ and Ni2+ ions from wastewater. Acknowledgements Authors are thankful to the University Grants Commission (Ref. No.: R-Dev-S. UGC-Research Fellow/2012-13/6417/01-06-2012), India for providing financial support and Institute of Environment and Sustainable Development and Centre of Advanced Study in Botany, Banaras Hindu University (BHU), Varanasi, India for providing necessary infrastructure. Authors are also thankful to the staff of Department of Chemistry, BHU and National Electron Microscope Facility, Department of Metallurgy, Indian Institute of Technology, Banaras Hindu University, Varanasi, India for FT-IR and SEM-EDX characterization.

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References Abdel-Razek, A., 2011. Removal of chromium ions from liquid waste solutions using immobilized Cunninghamella elegans. Nat. Sci. 9, 211–218. Ahmel, S., Mustafa, T., Demirhan, C., 2007. Adsorption characteristics of Cu(II) and Pb (II) onto expanded perlite from aqueous solution. J. Hazard. Mater. 148, 387–394. Aksu, Z., Acikel, U., 1999. A single-staged bioseparation process for simultaneous removal of copper(II) and chromium(VI) by using C. Vulgaris. Process Biochem. 34 (6/7), 589–599. Aldor, I., Fourest, E., Volesky, B., 1995. Desorption of cadmium from algal biosorbent. Can. J. Chem. Eng. 73, 516–522. APHA, 2012. Standard Methods for the Examination of Water and Wastewater, 22nd Ed. American Public Health Association, American Water Works Association and Water Environment Federation, Washington, D.C. Argun, M.E., Dursun, S., 2008. A new approach to modification of natural adsorbent for heavy metal adsorption. Bioresour. Technol. 99, 2516–2527. Babel, S., Kurniawan, T.A., 2000. Cr(VI) removal from synthetic wastewater using coconut shell charcoal and commercial activated carbon modified with oxidizing agents and/or chitosan. Chemosphere 54, 951–967. Baig, K.S., Doan, H.D., Wu, J., 2009. Multicomponent isotherms for biosorption of Ni2 + and Zn2+. Desalination 249, 429–439. Baral, S.S., Das, N., Chaudhury, G.R., Das, S.N., 2009. A preliminary study on the adsorptive removal of Cr(VI) using seaweed, Hydrilla verticillata. J. Hazard. Mater. 171, 358–369. Bhatti, H.N., Amin, M., 2013. Removal of zirconium(IV) from aqueous solution by Coriolus versicolor: equilibrium and thermodynamic study. Ecol. Eng. 51, 178– 180. Bhatti, H.N., Hamid, S., 2014. Removal of uranium(VI) from aqueous solutions using Eucalyptus citriodora distilliation sludge. Int. J. Environ. Sci. Technol. 11, 813–822. Bhatti, H.N., Saleem, A., Hanif, M.A., 2013. Utilization of Mentha arvensis waste biomass for the removal of Pb(II) and Co(II) from aqueous solutions. Desalin. Water Treat. 51, 3335–3343. Biesuz, R., Pesavento, M., Gonzalo, A., Valiente, M., 1997. Sorption of proton and heavy metal ions on a macroporous chelating resin with an iminodiacetate active group as a function of temperature. Talanta 47, 127–136. Bokare, A.D., Choi, W., 2014. Review of iron-free Fenton-like systems for activating H2O2 in advanced oxidation processes. J. Hazard. Mater. 275, 121–135. Borba, C.E., Guirardello, R., Silva, E.A., Veit, M.T., Tavares, C.R.G., 2006. Removal of nickel(II) ions from aqueous solution by biosorption in a fixed bed column: experimental and theoretical breakthrough curves. Biochem. Eng. J. 30, 184–191. Bureau of Indian Standard Specification, IS, India. 1993 Cardoso, de Souza, A.G., Sartoratto, P.P.C., Nunes, L.M., 2004. The ionic exchange process of cobalt: nickel and copper(II) in alkaline and acid-layered titanates. Colloid Surface A. 248, 145–149. Carol, D., Kingsley, S., Vincent, S., 2012. Hexavalent chromium removal from aqueous solutions by Pleurotus ostreatus spent biomass. Int. J. Eng. Sci. 4, 7–22. Chojnacka, K., Chojnacki, A., Gorecka, H., 2005. Biosorption of Cr3+, Cd2+ and Cu2+ ions by blue-green algae Spirulina sp.: kinetics, equilibrium and the mechanism of the process. Chemosphere 59 (1), 75–84. Congeevaram, S., Dhanarani, S., Park, J., Dexilin, M., Thamaraiselvi, K., 2007. Biosorption of chromium and nickel by heavy metal resistant fungal and bacterial isolates. J. Hazard. Mater. 146, 270–277. Dakiky, M., Khamis, M., Manassra, A., Mer’eb, M., 2002. Selective adsorption of chromium (VI) in industrial wastewater using low-cost abundantly available adsorbents. Adv. Environ Res. 6 (4), 533–540. Davis, T.A., Volesky, B., Vieira, R.H.S.F., 2000. Sargassum seaweed as biosorbent for heavy metals Sargassum seaweed as biosorbent for heavy metals. Water Res. 34, 4270–4278. DeForest, D., Brix, K., Adams, W., 2007. Assessing metal bioaccumulation in aquatic environments: the inverse relationship between bioaccumulation factors trophic transfer factors and exposure concentration. Aquat. Toxicol. 84, 236–246. Donais, M.K., Henry, R., Rettberg, T., 1999. Chromium speciation using an automated liquid handling system with inductively coupled plasma-mass spectrometric detection. Talanta 49, 1045–1050. Dyer, S.D., Peng, C., Mc Avoy, D.C., Fendinger, N.J., Masscheleyn, P., Castillo, L.V., Lim, J.M.U., 2003. The influence of untreated wastewater to aquatic communities in the Balatuin River, the Philippines. Chemosphere 52, 43–53. Environmental Protection Agency (EPA), USA, National pollutant discharge elimination system (NPDES); 2004 [http://www.cfpub.epa.gov/npdes/home. cfm?program_id=3]. Esalah, O.J., Weber, M.E., Vera, J.H., 2000. Removal of lead: cadmium and zinc from aqueous solutions by precipitation with sodium di-(n-octyl) phosphinate. Can. J. Chem. Eng. 78, 948–954. Ferrarese, E., Andreottola, G., Oprea, I.A., 2008. Remediation of PAH-contaminated sediments by chemical oxidation. J. Hazard. Mater. 52, 128–139. Freundlich, H.M.F., 1906. Over the adsorption in solution. J. Phys. Chem.-US 57, 385–470. Fritz, W., Schluender, E.U., 1974. Simultaneous adsorption equilibria of organic solutes in dilute aqueous solutions on activated carbon. Chem. Eng. Sci. 29 (5), 1279–1282. Fu, F., Wang, Q., 2011. Removal of heavy metal ions from wastewaters: a review. J. Environ. Manage. 92, 407–418.

Garcia-Rosales, G., Colin-Cruz, A., 2010. Biosorption of lead by maize (Zea mays) stalk sponge. J. Environ. Manage. 91, 2079–2086. Gupta, N., Amritphale, S.S., Chandra, N., 2010. Removal of Zn(II) from aqueous solution by using hybrid precursor of silicon and carbon. Bioresour. Technol. 101, 3355–3362. Hawari, A.H., Mulligan, C.N., 2006. Biosorption of lead(II) cadmium(II) copper(II) and nickel(II) by anaerobic granular biomass. Bioresour. Technol. 97, 692–700. HoY, McKay, G., 1999. Pseudo-second order model for sorption process. Process Biochem. 34, 451–465. Horsfall Jr., M., Abia, Spiff, A.A., 2006. Kinetic studies on the adsorption of Cd2+, Cu2+ and Zn2+ ions from aqueous solutions by cassava (Manihot sculenta Cranz) tuber bark waste. Bioresour. Technol. 97, 283–291. Huang, L., Zeng, G., Huang, D., Li, L., Du, C., Zhang, L., 2010. Biosorption of cadmium (II) from aqueous solution onto Hydrilla verticillata. Environ. Earth Sci. 60, 1683– 1691. Iqbal, J.M., Cecil, F., Ahmad, K., Iqbal, M., Mushtaq, M., Naeem, M.A., Bokhari, T.H., 2013. Kinetic study of Cr(III) and Cr(VI) biosorption using Rosa damascena phytomass: a rose waste biomass. Asian J. Chem 25, 2099–2103. Ishfaq, T., Naveed, S., Kazmia, M., Bhatti, H.N., Ferozea, N., 2013. A detailed investigation on engineering parameters for Cd(II) removal by ripped Citrus paradise pulp waste. J. Chil. Chem. Soc. 58 (N4) . Janson, C.E., Kenson, R.E., Tucker, L.H., 1982. Treatment of heavy metals in wastewaters. Environ. Prog. 1, 212–216. Kadirvelu, K., Thamaraiselvi, K., Namasivayam, C., 2001. Adsorption of nickel(II) from aqueous solution onto activated carbon prepared from coir pith. Sep. Purif. Technol. 24, 497–505. Kakarla, P.K., Andrews, T., Greenberg, R.S., Zervas, D., 2002. Modified-Fenton’s processes for effective in-situ chemical oxidation-laboratory and field evaluation. Remediat. J. 12, 23–36. Kanchana, S., Jeyanthi, J., Kumar, R.R.D., 2011. Equilibrium and kinetic studies on biosorption of chromium (VI) on to Chlorella species. Eur. J. Sci. Res. 63, 255–262. Karthikeyen, T., Rajgpal, S., Miranda, L.R., 2005. Cr(VI) adsorption from aqueous solution by Hevea brasilinesis saw dust activated carbon. J. Hazard. Mater. 124, 192–199. Kausara, A., Bhatti, H.N., MacKinnon, G., 2013. Equilibrium: kinetic and thermodynamic studies on the removal of U(VI) by low cost agricultural waste. Colloid Surface B: Biointerfaces 111, 124–133. Khezami, L., Capart, R., 2005. Removal of chromium(VI) from aqueous solution by activated carbons: kinetic and equilibrium studies. J. Hazard. Mater. 123, 223–231. Khowala, L.R.S., 2012. Effect of pretreatment on hexavalent chromium biosorption and multimetal biosorption efficiency of Termitomyces clypeatus biomass. Int. J. Integr. Sci. Innovat. Technol. 1, 7–15. Kratochvil, D., Pimentel, P., 1998. Advances in the biosorption of heavy metals. Trends Biotechnol. 16, 291. Kratochvil, D., Pimentel, P., Volesky, B., 1998. Removal of trivalent and hexavalent chromium by seaweed biosorbent. Environ. Sci. Technol. 32, 2693. Kumar, Y.P., King, P., Prasad, V.S.R.K., 2006. Zinc biosorption on Tectona grandis L.f. leaves biomass: Equilibrium and kinetic studies. Chem. Eng. J. 124, 63–70. Lagergren, S., 1898. About the theory of so called adsorption of solute substances. Kungliga Svenska, Vetenskapsakad. Handlingar Band. 24 (4), 1–39. Lai, C.L., Lin, S.H., 2003. Electrocoagulation of chemical mechanical polishing (CMP) wastewater from semiconductor fabrication. Chem. Eng. J. 95, 205–211. Langmuir, I., 1916. The adsorption gasses on plane surface of glass, mica and platinum. J. Am. Chem. Soc. 40, 1361–1368. Li, C.W., Chen, Y.M., Hsiao, S.T., 2008. Compressed air-assisted solvent extraction (CASX) for metal removal. Chemosphere 71, 51–58. Li, G.Z., Yan, C.Z., Zhang, D.D., Zhao, C., Chen, G.Y., 2013. Cadmium(II) biosorption from aqueous solutions using Hydrilla verticillata. Can. J. Chem. Eng. 91, 1022–1030. Manohar, D.M., Krishnan, K.A., Anirudhan, T.S., 2002. Removal of mercury(II) from aqueous solutions and chlor-alkali industry wastewater using 2 mercaptobenzimidazole–clay. Water Res. 36 (6), 1609–1619. McKay, G., Al Duri, B., 1989. Prediction of multicomponent biosorption equilibrium data using empirical correlations. J. Chem. Eng. 41 (1), 9–23. Miretzky, P., Munoz, C., 2011. Enhanced metal removal from aqueous solution by Fenton activated macrophyte biomass. Desalination 271, 20–28. Mohsen-Nia, M., Montazeri, P., Modarress, H., 2007. Removal of Cu2+ and Ni 2+from wastewater with a chelating agent and reverse osmosis processes. Desalination 217, 276–281. Munter, R., 2001. Advanced oxidation processes-current status and prospects. Proc. Estonian Acad. Sci. Chem. 59–65. Naveen, N., Saravanan, P., Baskar, G., Renganathan, S., 2011. Equilibrium and kinetic modeling on the removal of Reactive Red 120 using positively charged Hydrilla verticillata. J. Taiwan Inst. Chem. Eng. 42, 463–469. Nidheesh, P.V., Gandhimati, R., Ramesh, S.T., 2013. Degradation of dyes from aqueous solution by Fenton processes: a review. Environ. Sci. Pollut. Res. 20, 2099–2132. Nigam, S., Gopal, K., Vankar, P.S., 2013. Biosorption of arsenic in drinking water by submerged plant: Hydrilla verticilata. Environ. Sci. Pollut. Res. 20, 4000–4008. Nordin, N., Zakaria, Z.A., Ahmad, W.A., 2012. Utilisation of rubber wood shavings for the removal of Cu(II) and Ni(II) from aqueous solution. Water Air Soil Pollut. 223, 1649–1659. Ouki, S.K., Kavannagh, M., 1999. Treatment of metals-contaminated wastewaters by use of natural zeolites. Water Sci. Technol. 39, 115–122.

A. Mishra et al. / Ecological Engineering 73 (2014) 713–723 Pignatello, J.J., Oliveros, E., MacKay, A., 2006. Advanced oxidation processes for organic contaminant destruction based on the Fenton reaction and related chemistry. Crit. Rev. Environ. Sci. Technol. 36, 1–84. Pouran, S.R., Raman, A.A.A., Daud, W.M.A.W., 2013. Review on the application of modified iron oxides as heterogeneous catalysts in Fenton reactions. J. Clean Prod. 64, 24–35. Puranik, P.R., Paknikar, K.M., 1999. Biosorption of lead, cadmium, and zinc by Citrobacter strain MCM B-181: characterization studies. Biotechnol. Progr. 15, 228–237. Rai, P.K., Tripathi, B.D., 2008. Heavy metals in industrial wastewater, soil and vegetables in Lohta village, India. Toxicol. Environ. Chem. 90 (2), 247–257. Ronda, A., Martin-Lara, M.A., Calero, M., Blazquez, G., 2013. Analysis of the kinetics of lead biosorption using native and chemically treated olive tree pruning. Ecol. Eng. 58, 278–285. San Sebastian, N., Fernandez, J.F., Segura, X.F., Ferrer, A.S., 2003. Pre-oxidation of an extremely polluted industrial wastewater by the Fenton’s reagent. J. Hazard. Mater. 101, 315–322. Sasmaz, A., Obek, E., 2009. The accumulation of arsenic, uranium, and boron in Lemna gibba L. exposed to secondary effluents. Ecol. Eng. 35 (10), 1564–1567. Saygideger, S., Gulnaz, O., Salih, E., Yucel, N., 2005. Adsorption of Cd(II), Cu(II) and Ni (II) ions by Lemna minor L.: effect of physicochemical environment. J. Hazard. Mater. B126, 96–104. Sharain-Liew, Y.L., Joseph, C.G., How, S.-E., 2011. Biosorption of lead contaminated wastewater using cattails (Typha angustifolia) leaves: kinetic studies. J. Serb. Chem. Soc. 76, 1037–1047.

723

Sheng, P.X., Ting, Y.P., Chen, J.P., Hong, L., 2004. Sorption of lead, copper, cadmium, zinc, and nickel by marine algal biomass: characterization of biosorptive capacity and investigation of mechanisms. J. Colloid Interf. Sci. 275, 131–141. Shukla, S.R., Pai, R.S., 2005. Adsorption of Cu(II): Ni(II) and Zn(II) on modified jute fibres. Bioresour. Technol. 96, 1430–1438. Taty-Costodes, V.C., Fauduet, H., Porte, C., Delacroix, A., 2003. Removal of Cd(II) and Pb(II) ions, from aqueous solutions, by adsorption onto sawdust of Pinus sylvestris. J. Hazard. Mater. B 105, 121–142. Tripathi, S., Pathak, V., Tripathi, D.M., Tripathi, B.D., 2011. Application of ozone based treatments of secondary effluents in the tropical cities. Bioresour. Technol. 102, 2481–2486. Valderrama, C., Alessandri, R., Aunola, T., Cortina, J.L., Gamisans, X., Tuhkanen, T., 2009. Oxidation by Fenton's reagent combined with biological treatment applied to a creosote-comtaminated soil. J. Hazard. Mater. 166, 594–602. Venny Gan, S., Ng, H.K., 2012. Current status and prospects of Fenton oxidation for the decontamination of persistent organic pollutants (POPs) in soils. Chem. Eng. J. 213, 295–317. Vijayaraghavan, K., Palanivelu, K., Velan, M., 2006. Biosorption of copper(II) and cobalt(II) from aqueous solutions by crab shell particles. Bioresour. Technol. 97, 1411–1419. Wang, X.S., Qin, Y., 2006. Removal of Ni(II), Zn(II) and Cr(VI) from aqueous solution by Alternanthera philoxeroides biomass. J. Hazard. Mater. B 138, 582–588. Yuan, X.Z., Meng, Y.T., Zeng, G.M., Fang, Y.Y., Shi, J.G., 2008. Evaluation of tea-derived biosurfactant on removing heavy metal ions from dilute wastewater by ion flotation. Colloid Surface A 317, 256–261.