Three-Dimensional Patient-Specific Guides for Intraoperative Navigation for Cortical Screw Trajectory Pedicle Fixation

Article Journal of Nanoscience and Nanotechnology

Copyright © 2019 American Scientific Publishers All rights reserved Printed in the United States of America

Vol. 19, 1014–1017, 2019 www.aspbs.com/jnn

Efficient Spent Sulfidic Caustic (SSC) Wastewater Treatment Using Nano TiO2 -Bottom Ash (NTB) Composite Jong Kyu Kim1 , Jong Ho Kim2 , Luiza Campos3 ∗ , Jin Chul Joo4 ∗ , and Woochang Jeong1 ∗ 1

Department of Civil Engineering, Kyungnam University, Changwon, 51767, Republic of Korea Department of Chemical Engineering, Chonnam National University, 61186, Republic of Korea 3 Department of Civil, Environmental and Geomatic Engineering, University College London, WC1E 6BT, UK 4 Department of Civil and Environmental Engineering, Hanbat National University, 34158, Republic of Korea 2

Novel composites with nano-sized TiO2 synthesized on the surface of bottom ash (NTB) were prepared for treatment of spent sulfidic caustic (SSC) wastewater. The efficiency of SSC wastewater treatment was compared and evaluated by using NTBs made with organic binder and inorganic binder, respectively. The treatment efficiency of NTB composite made with organic binder was higher than that of NTB composite made with inorganic binder. Although NBT composite made with inorganic binder had many pores on the surface, the white cement used as binder was excessively applied to the surface, and amount of coated nano-sized TiO2 was decreased. The photocatalytic activity of nano-sized TiO2 is more effective for SSC wastewater treatment than surface adsorption ability of surface pores.

IP: 5.62.152.41 On: Thu, 10 Jan 2019 00:46:42

Keywords: Spent Sulfidic Caustic, American Photocatalysis, BottomPublishers Ash, TiO2 , NTB Composite. Copyright: Scientific Delivered by Ingenta

1. INTRODUCTION Spent sulfidic caustic (SSC) wastewater from a petrochemical plant is produced during the refining process of Liquefied Petroleum Gas (LPG) or Natural Gas (NG).1 2 It contains high concentration of sulfide and cresylic, phenolic and mercaptan which are toxic and odorous. These impurities are generated by the reaction of NaOH used with H2 S to remove volatile sulfur compounds during LPG or NG refining process. A typical SSC wastewater comes in dark brown to black and contains 5–12 wt% NaOH, 0.1–4 wt% S2− and high alkalinity (pH > 12).1–3 The high pH and high concentration of sulfide in SSC wastewater limit direct biological treatment and tend to have high COD load. Accordingly, special and effective treatment process for SSC wastewater is required before being discharged to a conventional wastewater treatment plant. Numerous processes have been made in order to treat SSC wastewater associated with physico-chemical process including precipitation, wet air oxidation (WAO), incineration and oxidation with strong oxidant agent, thermal, biological or bio-electrochemical processes.3 In spite of using various processes to treat SSC wastewater, there ∗

Authors to whom correspondence should be addressed.

1014

J. Nanosci. Nanotechnol. 2019, Vol. 19, No. 2

are many difficulties to apply directly in the field because of many restrictions such as cost, high consumption of chemicals, complexity and safety problem. Among various types of SSC wastewater treatment processes, heterogeneous photocatalysis using suspended TiO2 or ZnO powders gained increased attention owing to the potential to degrade complex chemical mixtures using highly reactive transitory species such as hydroxyl radicals superoxide radicals and singlet oxygen.4 Moreover TiO2 or ZnO photocatalysts are chemically stable over wide pH range and safely handled.4 In order to achieve the required level of treatment photocatalysis is usually paired with other treatment process such as adsorption process. Kim et al.4 produced TCNSP composite which is synthesized TiO2 with coconut shell powder to remove humic acid in water. In addition, Joo et al.5 developed nanoZnO/Laponite composite to mineralize TCE without difficulties for recovery of ZnO photocatalysts and increase adsorption ability. However, in these cases, the use of adsorbents or supports for photocatalysts increase the overall treatment cost. Moreover, since the SSC wastewater has a high COD concentration and a high sulfide level, it is not economically desirable to treat the SSC wastewater by applying an adsorbent such as activated carbon with a 1533-4880/2019/19/1014/004

doi:10.1166/jnn.2019.15964

Kim et al.

Efficient Spent Sulfidic Caustic (SSC) Wastewater Treatment Using Nano TiO2 -Bottom Ash (NTB) Composite

high price. Therefore, it is preferable to apply a material capable of securing an inexpensive and abundant amount and capable of supporting photocatalysts. Coal bottom ash can be a good candidate of photocatalyst supporter as it is a material produced in a furnace with a high calcining temperature of 800  C or higher by-products generated from a coal-fired thermal power plant and it has a porous inorganic component and is well suited for producing an adsorbent. In addition, bottom ash has a much larger surface area to volume ratio than most substrates such as sand or clay. Thus, by using bottom ash as a photocatalyst and as an adsorbent, for producing a novel composite, the photocatalytic activity of TiO2 and the adsorption action of the bottom ash work together to produce a synergistic effect can be obtained. Therefore, in this study, a novel composite with nanosized TiO2 synthesized on the surface of bottom ash (NTB) was prepared. The efficiency of SSC wastewater treatment was compared and evaluated by using organic binder and inorganic binder, respectively. XRD and SEM analysis was performed to evaluate the surface properties of the prepared NTB composites. Figure 2.

Lab-scaled batch reactor.

2. EXPERIMENTAL PROCEDURES were sprayed on the surface of composite, and finally 2.1. Preparation of NTB Composites NTB composite was prepared. In case of inorganic binders, In this study, NTB composites were synthesized by the white cement was applied in place of PVA, and NTB was chemical solution method. All raw IP: materials were ofOn: ana-Thu, 10 5.62.152.41 Jan 2019 00:46:42 prepared Publishers in the same order. Copyright: (99.7%American purity, Scientific lytical grade. Nano-sized TiO2 particles Delivered by Ingenta <25 nm particle size) were purchased from Sigma2.2. Physicochemical Properties and Treatment Aldrich. Bottom ash was provided from Donghae therEfficiency of NTB Composite moelectric power plant in South Korea with an average In order to characterize the space structure and crystalline diameter 3∼5 mm. The organic binder, PVA (P17, Visphase of NTB composite, scanning electron microscopy cosity 25.5–28.6cP) were supplied by Daemyung Chem(SEM, HITACHI, S-4700) and X-ray diffraction (XRD, ical. The inorganic binder, white cement (Density: about 3 Rigaku Rint 2000, Japan) analyses were performed. Total 1.97 g/cm  was supplied by Union Cement Company. organic canbon (TOC) were determined to evaluate the PVA powder was mixed with deionized water in the efficiency of NTB using a 5000TOCi analyzer (Mettler ratio of 10 g:50 ml, and the resulting solution was stirred Toledo, USA). for 1.5 h by heating at 150  C to dissolve PVA powder. After that, washed bottom ash particles were mixed with 2.3. Lab-Scaled Batch Experiments dissolved PVA glue in the ratio of 100 g:10 ml. Then the In order to evaluate the performance of NTB composmixture was moved to NTB mold (Fig. 1) to be prepared ites made with organic and inorganic binders, experiments in the form of a square. After 5 minutes, the squared comwere conducted using a lab-scaled batch reactor (Fig. 2). posite was demolded and then nano-sized TiO2 powder The reactor consists of rectangular box employing a UV lamp mounted vertically inside the reactor, and all parts were made with acrylic material. All experiments were performed in triplicate with the same initial concentration.

3. RESULTS AND DISCUSSION

Figure 1.

The picture of NTB mold.

J. Nanosci. Nanotechnol. 19, 1014–1017, 2019

3.1. Characterization of NTB Composites Made from Organic and Inorganic The structure and crystalline phase characterization of the newly prepared NTB composites were evaluated by XRD and SEM analysis. As shown in Figure 3 the main peak 1015

Efficient Spent Sulfidic Caustic (SSC) Wastewater Treatment Using Nano TiO2 -Bottom Ash (NTB) Composite

Figure 3.

Kim et al.

IP: 5.62.152.41 On: Thu, 10 Jan 2019 00:46:42 Copyright: American Scientific Publishers Delivered by Ingenta

X-ray diffraction graphs of composites made with inorganic binder and organic binder.

(marked in red circle) was observed at 25.4 in each NTB composite made with inorganic and organic binders. These results indicated that the nano-sized TiO2 (anatase type) used as a photocatalyst in this study is well coated onto surface of the composites. Other peaks (marked with blue arrows) of the composites made with inorganic binders are inherent peaks of cement used as inorganic binder. The surface morphology of the NTB composites was also observed by SEM analysis. Figure 4 shows that the raw bottom ash particle surface (without binder), the bottom ash particle surface coated with an organic binder,

and the bottom ash particle surface coated with an inorganic binder, respectively. As shown in Figure 4, the pores were not detected in the surface of the raw bottom ash particle without the binder (Fig. 4(a)). And the surface was almost flat and dense, and therefore it is considered that raw bottom ash has almost no adsorption capacity in water. On the other hand, in the case of a bottom ash coated with an organic binder (Fig. 4(b)), the surface was rugged and had some pores. Also, a bottom ash coated with an inorganic binder (Fig. 4(c)) had a large amount of pores in

Figure 4. Pictorial images of (a) raw bottom ash particle (b) bottom ash particle coated with organic binder (c) bottom ash particle coated with inorganic binder.

1016

J. Nanosci. Nanotechnol. 19, 1014–1017, 2019

Kim et al.

Figure 5.

Efficient Spent Sulfidic Caustic (SSC) Wastewater Treatment Using Nano TiO2 -Bottom Ash (NTB) Composite

The NTB composites.

compared with raw bottom ash or organic binder coated bottom ash. Furthermore, the surface of this bottom ash was very bumpy, and sharp liner crystals appeared. This is similar to the phenomenon appearing on the surface of cured materials using cement. It is considered that the rough surface and the large amount of pores can easily adsorb the pollutants in the water to the surface.

obtained by the first pre-treatment, and the initial TOC concentration of this wastewater was 1,200 mg/L. Figure 6 shows the results of SSC wastewater treatment efficiency of NTB composites prepared using different binder. The treatment efficiency of NTB composite made with organic binder was higher than that of NTB composite made with inorganic binder. These results indicated that although NBT composite made with inorganic binder had many pores on the surface, the white cement used as binder was excessively applied to the surface, and amount of exposed nano TiO2 was decreased. Therefore, it is considered that photocatalytic oxidation of the nano TiO2 was less than that of the NTB made with organic binder. In conclusion, the photocatalytic activity of nano TiO2 is more effective for SSC wastewater treatment than surface adsorption ability.

4. CONCLUSION 3.2. Investigation of the SSC Wastewater Treatment Novel composites with nano-sized TiO2 synthesized on Using Organic and Inorganic Binder the surface of bottom ash (NTB) were prepared for treatCoated NTB Composite ment of SSC wastewater. The efficiency of SSC wastewaFigure 5 shows the appearance of the NTB composites ter treatment was compared and evaluated by using NTB with photocatalytic ability and adsorption capacity. Labmade with organic binder and inorganic binder, respecscaled batch experiments were conducted to evaluate SSC tively. The treatment efficiency of NTB composite made wastewater treatment efficiency for each NTB composite with organic binder was higher than that of NTB composprepared using the organic and inorganic binders, respecite made with inorganic binder. In conclusion, the phototively. The SSC wastewater used IP: in the experimentOn: wasThu, 10 catalytic activity of nano TiO2 is more effective for SSC 5.62.152.41 Jan 2019 00:46:42 wastewater treatment than surface adsorption ability of surCopyright: American Scientific Publishers Delivered byface Ingenta pores. Acknowledgment: This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (Ministry of Education) (No. 2017R 1D 1A 1B03032181).

References and Notes

Figure 6.

SCC wastewater treatment efficiency using NTB composites.

1. A. Hawari, H. Ramadan, I. Abu-Reesh, and M. Ouederni, J. Environ. Manage. 151, 105 (2015). 2. E. Vaiopolou, T. Provijn, A. Prevoteau, I. Pikaar, and K. Rabaey, Water. Res. 92, 38 (2016). 3. I. B. Hariz, A. Halleb, N. Adhoum, and L. Monser, Sep. Purif. Technol. 107, 150 (2013). 4. J. K. Kim, D. G. Jang, L. C. Campos, Y. W. Jung, J. Kim, and J. C. Joo, J. Nanomater. 2016, 1 (2016). 5. J. C. Joo, C. H. Ahn, D. G. Jang, Y. H. Yoon, J. K. Kim, L. Campos, and H. Ahn, J. Hazard Mater. 263, 569 (2013).

Received: 20 December 2017. Accepted: 15 January 2018.

J. Nanosci. Nanotechnol. 19, 1014–1017, 2019

1017