Personal Research Database

Full Text: 2009\Wat Res43, 4336.pdf

Abstract: Polyethylene-water partitioning coefficients (K(PE)) and mass transfer coefficients (k(PE)) for the ortho and para isomers of the organochlorine pesticide dichlorodiphenyltrichloroethane (DDT) and its metabolites dichlorodiphenyldichloroethane (DDD), dichlorodiphenyldichloroethylene (DDE) and, dichlorodiphenylmonochloroethylene (DDMU) were measured. These data were used to derive activated carbon (AC) sorption isotherms in clean water in the sub-nanogram per litre free aqueous concentration range for a Virgin and a regenerated AC. The sorption strength of AC for DDT and its metabolites was very high and logarithmic values of the AC-water partitioning coefficients, logK(AC), ranged from 8.47 to 9.26. A numerical mass transfer model was calibrated with this data to interpret previously reported reductions in DDT uptake by semipermeable membrane devices after AC amendment of sediment from Lauritzen Channel, California, USA. The activated carbon-water partitioning coefficient values (K(AC)) measured in clean water systems appear to overestimate the AC sorption capacity in sediment up to a factor 32 for DDT and its metabolites at long contact time with fine-sized AC. Modelling results show decreased attenuation of the AC sorption capacity with increased sediment-AC contact time. We infer that increased resistance in mass transfer of DDTs to sorption sites in the microporous region likely caused by deposits of dissolved organic matter in the macro- and mesopores of AC appears to be the most relevant fouling mechanism. These results suggest that DDTs may diffuse through possible deposits of dissolved organic matter over time, implying that the effects of sediment on the sorption of DDTs by AC may be more kinetic than competitive. (c) 2009 Elsevier Ltd. All rights reserved.

Keywords: Activated Carbon, Activated Carbon Fouling, Adsorption, Capacity, Contaminated Sediment, Environmental Black Carbon, Isotherms, Macoma-Balthica, Marine Sediment, Mechanism, Metabolites, Model, Native Pahs, Organic-Compounds, Organochlorine Pesticide, Passive Sampling, Polychlorinated-Biphenyls, Polyethylene, Polyethylene Devices, Resistance, Semipermeable-Membrane Devices, Sorbent Amendment, Sorption, Strength, Uptake

? Chan, Y.T., Kuan, W.H., Chen, T.Y. and Wang, M.K. (2009), Adsorption mechanism of selenate and selenite on the binary oxide systems. Water Research, 43 (17), 4412-4420.

Full Text: 2009\Wat Res43, 4412.pdf

Abstract: Removal of selenium oxyanions by the binary oxide systems, Al- or Fe-oxides mixed with X-ray noncrystalline SiO(2), was previously not well understood. This study evaluates the adsorption capacity and kinetics of selenium oxyanions by different metal hydroxides onto SiO(2), and uses X-ray absorption spectroscopy (XAS) to assess the interaction between selenium oxyanions and the sorbents at pH 5.0. The binary oxide systems of Al(III)- or Fe(III)-oxides mixed with SiO(2) were prepared, and were characterized for their surface area, point of zero charge (PZC), pH envelopes, X-ray diffraction analysis (XRD), and then macroscale adsorption isotherm and kinetics of selenite and selenate, micro-scale adsorption XAS. The adsorption capacity of selenite and selenate on Al(III)/SiO(2) is greater than on Fe(III)/SiO(2). Adsorption isothermal and kinetic data of selenium can be well fitted to the Langmuir isotherm and pseudo-second-order kinetic models. Based on simple geometrical constraints, selenite on both the binary oxide systems forms bidentate inner-sphere surface complexes, and selenate on Fe(III)/SiO(2) forms stronger complexes than on Al(III)/SiO(2). (c) 2009 Elsevier Ltd. All rights reserved.

Keywords: Adsorption, Analysis, Binary Oxide Systems, Capacity, Coated Sand, Isotherm, Kinetic Models, Kinetics, Langmuir Isotherm, Mechanism, Mixed Oxides, Oxyanions, pH, Pseudo-Second-Order, Pseudo-Second-Order Kinetic Model, Removal, Selenium Oxyanions, Silicic-Acid, Sulfate Adsorption, Surface, Water, X-Ray Absorption Spectroscopy (XAS), X-Ray-Absorption, XRD

? Parab, H. and Sudersanan, M. (2010), Engineering a lignocellulosic biosorbent - Coir pith for removal of cesium from aqueous solutions: Equilibrium and kinetic studies. Water Research, 44 (3), 854-860.

Full Text: 2010\Wat Res44, 854.pdf

Abstract: A novel method of engineering lignocellulosic biosorbent- coir pith (CP) by incorporation of nickel hexacyanoferrate (NiHCF), also referred to as Prussian blue analogue (PBA) inside its porous matrix is reported. Structural characterization confirmed the successful synthesis of NiHCF in the coir pith matrix. Sorption capacity of coir pith (CP) before and after loading of NiHCF was investigated for cesium (Cs) in batch equilibrium studies. Kinetic studies showed that the sorption process was rapid and saturation was attained within 30 min. The applicability of non linear Langmuir, Freundlich and Redlich Peterson isotherms was examined for the experimental data. The present studies revealed that there was nearly 100% increase in the sorption capacity of CP after its surface modification with NiHCF. Owing to its low cost, fast sorption kinetics and high uptake capacity, coir pith loaded with NiHCF (CP-NiHCF) seems to be one of the most promising biosorbents for recovery of cesium from liquid nuclear wastes. (c) 2009 Elsevier Ltd. All rights reserved.

Keywords: Adsorption, Biosorption, Capacity, Cesium, Characterization, Chemically-Modified Biomass, Clinoptilolite, Coir Pith, Electrochemical Properties, Equilibrium, Isotherms, Kinetic, Kinetics, Lignocellulosic, Modification, Nickel Hexacyanoferrate, Nickel Hexacyanoferrate, Nuclear Waste Solutions, Prussian Blue, Recovery, Removal, Self-Assembled Films, Sorption, Sorption, Sorption Kinetics, Uptake

? Luo, P., Zhao, Y.F., Zhang, B., Liu, J.D., Yang, Y. and Liu, J.F. (2010), Study on the adsorption of Neutral Red from aqueous solution onto halloysite nanotubes. Water Research, 44 (5), 1489-1497.

Full Text: 2010\Wat Res44, 1489.pdf

Abstract: Halloysite nanotubes (HNTs), a low-cost available clay mineral, were tested for the ability to remove cationic dye, Neutral Red (NR), from aqueous solution. Natural HNTs used as adsorbent in this work were initially characterized by XRD, FT-IR, TEM and BET. The effect of adsorbent dose, initial pH, temperature, initial concentration and contact time were investigated. Adsorption increased with increase in adsorbent dose, initial pH, temperature and initial concentration. The equilibrium data were well described by both the Langmuir and Freundlich isotherm models. The maximum adsorption capacity was 54.85, 59.24 and 65.45 mg/g at 298, 308 and 318 K, respectively. Batch kinetic experiments showed that the adsorption followed pseudo-second-order kinetic model with correlation coefficients greater than 0.999. Thermodynamic parameters of Delta G(0), Delta H(0) and Delta S(0) indicated the adsorption process was spontaneous and endothermic. The results above confirmed that HNTs had the potential to be utilized as low-cost and relatively effective adsorbent for cationic dyes removal. (C) 2009 Elsevier Ltd. All rights reserved.

Keywords: Activated Carbons, Adsorbent, Adsorption, Basic-Dyes, Capacity, Cationic Dyes, Clay Nanotubes, De-Oiled Soya, Dye Adsorption, Equilibrium, Ftir, Halloysite, Halloysite Nanotubes, Industry Waste, Isotherm, Isotherm Models, Kinetic Model, Methylene-Blue, Model, Natural Halloysite, Neutral Red, pH, Pseudo-Second-Order, Removal, Thermodynamic, Thermodynamic Parameter, Thermodynamic Parameters, Waste-Water, XRD

? Hosseini, S.D., Asghari, F.S. and Yoshida, H. (2010), Decomposition and decoloration of synthetic dyes using hot/liquid (subcritical) water. Water Research, 44 (6), 1900-1908.

Full Text: 2010\Wat Res44, 1900.pdf

Abstract: We have studied the decomposition and decoloration of 4-(2-Hydroxynaphthylazo) benzenesulfonic acid sodium salt (AO7, acid dye) as a model for textile wastes by using a flow-type subcritical water system. The operating temperature was ranged from 180 to 374 degrees C at 10-25 MPa at a wide range of residence time. The pressure (up to 25 MPa) did not affect the decomposition reactions. AO7 completely decomposed at higher temperatures and or longer residence times. The main products from decomposition of AO7 were found to be 2-naphthalenol, phenol, 1,1’-Binaphthalene-2,2’-diol, and N-(phenylmethylene)benzenamine. In order to identify the decomposition pathways, the products were also individually treated under a batch type subcritical water conditions. We found that 2-naphthalenol underwent to further decomposition to 1,1’-Binaphthalene-2,2’-diol during the subcritical water reaction. Other decomposition products resulted from the decomposition of directly AO7. Kinetic model of the subcritical water reaction was developed by considering major products. The kinetic constants obtained from the proposed reaction pathway showed good agreement with experimental results. (C) 2009 Elsevier Ltd. All rights reserved.

Keywords: 2-Naphthalenol, Acid Dye, Acid Orange 7, Adsorption, Azo, Basic Dye, Cellulose Membrane, Decoloration, Degradation, Diffusion, Kinetic, Kinetic Model, Low-Cost Adsorbent, Model, Phenol, Pressure, Subcritical Water, Textile Wastewater, Waste-Water

? Ispas, C.R., Ravalli, M.T., Steere, A. and Andreescu, S. (2010), Multifunctional biomagnetic capsules for easy removal of phenol and bisphenol A. Water Research, 44 (6), 1961-1969.

Full Text: 2010\Wat Res43, 1961.pdf

Abstract: This paper reports fabrication, optimization and characterization of multifunctional biocapsules with immobilized enzyme using a layer-by-layer configuration and their application for removal of phenol and bisphenol A (BPA). The method is based on the combined use of enzymatic oxidation of the BPA and subsequent binding of the reaction product onto a chitosan core biopolymer. This platform has multiple functions including: (1) enzymatic degradation of BPA, (2) adsorption of the degraded compound within the core material, (3) colorimetric quantification and (4) magnetic capabilities. We examined various configurations of core/shell structures of alginate and chitosan and determined the stability and the optimum conditions in which these structures provide the most effective removal capacity. The amount of BPA that can be removed per capsule is 5.6 ppm while phenol can be removed up to 10 ppm per capsule within 15 h.

Keywords: Bisphenol A, Phenol, Removal, Microencapsulation, Tyrosinase, Chitosan, Biocapsules

? Stutter, M.I., Demars, B.O.L. and Langan, S.J. (2010), River phosphorus cycling: Separating biotic and abiotic uptake during short-term changes in sewage effluent loading. Water Research, 44 (15), 4425-4436.

Full Text: 2010\Wat Res44, 4425.pdf

Abstract: Medium to small scale point sources continue to threaten river ecosystems through P loadings. The capacity and timescales of within-river processing and P retention are a major factor in how rivers respond to, and protect downstream ecosystems from, elevated concentrations of soluble reactive P (SRP). In this study, the bio-geochemical response of a small river (similar to 40 km(2) catchment area) was determined before, during and after exposure to a fourteen day pulse of treated sewage effluent using an upstream reach as a control. A wide array of approaches (batch and column simulations to in-situ whole stream metabolism) allowed independent comparison and quantification, of the relative contribution of abiotic and biotic processes in-river P cycling. This enabled, for the first time, separating the relative contributions of algae, bacteria and abiotic sorption without the use of labelled P (radioisotope). An SRP mass balance showed that the ecosystem switched from a P sink (during effluent inputs) to a P source (when effluent flow ceased). However, 65-70% of SRP was retained during the exposure time and remained sequestered two-weeks after-effluent flow ceased. Batch studies treated with biocide gave unrealistic results, but P uptake rates derived by other methods were highly comparable. Downstream of the effluent input, net P uptake by algae, bacteria and sediment (including the biofilm polysaccharide matrix) were 0.2 (+/- 0.1), 0.4 (+/- 0.3), and 1.0 (+/- 0.9) mmol m(-2) day(-1) during effluent exposure. While autotrophic production did not respond to the effluent exposure, heterotrophic production increased by 67% relative to the control and this translated into a 50% increase in biological P uptake rate. Therefore, both biological and abiotic components of stream ecosystems uptake P during exposure to treated sewage effluent P inputs, and maintain a long ‘memory’ of this input in terms of P storage for considerable timescales after loading. (C) 2010 Elsevier Ltd. All rights reserved.

Keywords: Algal Assays, Bacteria, Balance, Bed-Sediments, Biofilm, Capacity, Contribution, Control, Dissolved Organic-Carbon, Dynamics, Ecosystem, Exposure, Kinetic Sorption Studies, Lowland Streams, Memory, Nutrient Spiralling, Nutrient-Uptake, Open Flow-Through Columns, Oxygen Change Technique, Phosphorus, Retention, Sediment-Phosphorus, Sorption, Stoichiometry, Uptake, Whole Stream Metabolism, Whole-Stream Metabolism

? Wainipee, W., Weiss, D.J., Sephton, M.A., Coles, B.J., Unsworth, C. and Court, R. (2010), The effect of crude oil on arsenate adsorption on goethite. Water Research, 44 (19), 5673-5683.

Full Text: 2010/Wat Res44, 5673.pdf

Abstract: This study reports the adsorption of arsenate, As(V), on goethite (alpha-FeO(OH)) and oil-coated goethite at experimental conditions chosen to mimic settings of wastewater from oil fields being released into marine and freshwater bodies. Similarities are evident between the As(V)-goethite and AsM-oil-goethite systems: i) Adsorption is fast and saturation is achieved within 180 min, ii) Reaction rates approximate to a pseudo second order rate expression and range between 6.5 and 52.3 x 10(-4) g/mu mol/min, iii) Adsorption mechanisms are best described with a Langmuir model, and iv) Adsorption capacity rises with decreasing pH reflecting the increase of positive charges on the goethite surface. A difference is discernable in that the adsorption of As(V) is reduced significantly when the goethite is coated with oil. The similar experimental macroscopic observations for both systems, i.e., Langmuir model fits, reaction rates, and the effect of pH and ionic strength (I), suggest that the oil reduces the effective and/or reactive surface area. The zeta potential () indicates that the oil coating also changes the surface charge of the goethite, shifting the pH point of zero charge from 9.8 to about 3, thus contributing to the reduced As(V) adsorption. FTIR spectra show that As(V) interacts with the carbonyl functional groups of the oil. Our results suggest that oil-covered goethite significantly reduces the adsorption of As(V) and this points to a potentially significant indirect effect of oil on the cycling of As(V) and other oxyanions in oil polluted waters. (C) 2010 Elsevier Ltd. All rights reserved.

Keywords: Adsorption, Adsorption Capacity, Adsorption Mechanisms, Alpha-Feooh, Arsenate, Arsenic, As(V), As(V) Adsorption, Bodies, Capacity, Changes, Charge, Coated, Coating, Crude Oil, Experimental, Expression, Ferrihydrite, Freshwater, FTIR, FTIR Spectra, Functional Groups, Goethite, Humic Substances, Ionic Strength, Iron-Oxide, Langmuir, Langmuir Model, Mechanisms, Mineral, Water Interfaces, Model, Nov, Oil, Oil And Gas Rigs, Organic-Matter, Oxide Minerals, pH, Point of Zero Charge, Potential, Production Waters, Pseudo Second Order, Pseudo-Second-Order, Rates, Rights, Saturation, Second Order, Second-Order, Si, Sorption, Strength, Surface, Surface Area, Surface Charge, Surface-Chemistry, Systems, Wastewater, Waters, Zeta Potential

? Yang, W.C., Kan, A.T., Chen, W. and Tomson, M.B. (2010), pH-dependent effect of zinc on arsenic adsorption to magnetite nanoparticles. Water Research, 44 (19), 5693-5701.

Full Text: 2010\Wat Res44, 5693.pdf

Abstract: The effect of Zn(2+) on both the kinetic and equilibrium aspects of arsenic adsorption to magnetite nanoparticles was investigated at pH 4.5-8.0. At pH 8.0, adsorption of both arsenate and arsenite to magnetite nanoparticles was significantly enhanced by the presence of small amount of Zn(2+) in the solution. With less than 3 mg/L of Zn(2+) added to the arsenic solution prior to the addition of magnetite nanoparticles, the percentage of arsenic removal by magnetite nanoparticles increased from 66% to over 99% for arsenate, and from 80% to 95% for arsenite from an initial concentration of similar to 100 mu g& As at pH 8.0. Adsorption rate also increased significantly in the presence of Zn(2+). The adsorption-enhancement effect of Zn(2+) was not observed at pH 4.5-6.0, nor with ZnO nanoparticles, nor with surface-coated Zn-magnetite nanoparticles. The enhanced arsenic adsorption in the presence of Zn(2+) cannot be due to reduced negative charge of the magnetite nanoparticles surface by zinc adsorption. Other cations, such as Ca(2+) and Ag(+), failed to enhance arsenic adsorption. Several potential mechanisms that could have caused the enhanced adsorption of arsenic have been tested and ruled out. Formation of a ternary surface complex by zinc, arsenic and magnetite nanoparticles is a possible mechanism controlling the observed zinc effect. Zinc-facilitated adsorption provides further advantage for magnetite nanoparticle-enhanced arsenic removal over conventional treatment approaches. Synopsis: Arsenic adsorption to magnetite nanoparticles at neutral or slightly basic pH can be significantly enhanced with trace amount of Zn(2+) due to the formation of a ternary complex. (C) 2010 Elsevier Ltd. All rights reserved.

Keywords: Adsorption, Arsenic, Chemistry, Desorption, Equilibrium, Goethite, Kaolinite, Magnetite Nanoparticles, Mechanism, Mechanisms, Oxidation, pH, Removal, Soils, Substances, Surface, Ternary Surface Complex, Treatment, Water Interface, Zinc

? Miller, S.M. and Zimmerman, J.B. (2010), Novel, bio-based, photoactive arsenic sorbent: TiO₂-impregnated chitosan bead. Water Research, 44 (19), 5722-5729.

Full Text: 2010\Wat Res44, 5722.pdf

Abstract: A novel sorbent for arsenic, TiO₂-impregnated chitosan bead (TICS), has been synthesized and successfully tested. Kinetic plots, pH dependence, isotherm data, and bead morphology are reported. Equilibrium is achieved after 185 h in batch experiments with exposure to UV light. The TICB system performs similarly to the mass equivalent of neat TiO₂ nanopowder. The point of zero charge (pzc) for TICB was determined to be 7.25, and as with other TiO₂-based arsenic removal technologies, the optimal pH range for sorption is below this pH(pzc). Without exposure to UV light, TICB removes 2198 mu g As(III)/g TICB and 2050 mu g As(V)/g TICB. With exposure to UV light, TICB achieves photo-oxidation of As (III) to As(V), the less toxic and more easily sequestered arsenic form. UV irradiation also results in enhanced arsenic removal, reaching sorption capacities of 6400 mu g As/g TICB and 4925 mu g As/g TICB, where arsenic is initially added as As(III) and As(V), respectively. Because the TICB system obviates filtration post-treatment, TICB is superior to TiO₂ nanopowder from the perspective of implementation for decentralized water treatment. (C) 2010 Elsevier Ltd. All rights reserved.

Keywords: Activated Alumina, Adsorption, Aqueous-Solutions, Arsenic, Bio-Based, Chitosan, Drinking-Water, Equilibrium, Exposure, Fixed-Bed, Isotherm, Kinetic, Nanocrystalline Titanium-Dioxide, pH, Photocatalytic Oxidation, Removal, Sorption, Sustainable, TiO₂, TiO₂-Photocatalyzed As(III) Oxidation, Treatment, Water, Water-Treatment

? Mao, J., Lee, S.Y., Won, S.W. and Yun, Y.S. (2010), Surface modified bacterial biosorbent with poly(allylamine hydrochloride): Development using response surface methodology and use for recovery of hexachloroplatinate (IV) from aqueous solution. Water Research, 44 (20), 5919-5928.

Full Text: 2010/Wat Res44, 5919.pdf

Abstract: In this study, poly(allylamine hydrochloride) (PAA/HCl) was cross-linked with fermentation bacterial waste (Escherichia coli) in order to introduce a large amount of amine groups as binding sites for potassium hexachloroplatinate(IV), as a model anionic pollutant. The sorption performance of PAA/HCl-modified E. coli was greatly affected by the dosages of PAA/HCl and crosslinker (epichlorohydrin, ECH), and by the pH of the modification reaction medium. These factors were optimized through the response surface methodology (RSM). A three-level factorial Box-Behnken design was performed, and a second-order polynomial model was successfully used to describe the effects of PAA/HCl, ECH and the pH on the Pt(IV) uptake (R-2 = 0.988). The optimal conditions that were obtained from the RSM were 0.49 g of PAA/HCl, 0.05 mL of ECH and pH 10.02, with 1.0 g of dried E. coli biomass. The biosorption isotherm and kinetics studies were carried out in order to evaluate the sorption potential of the PAA/HCl-modified E. coli that was prepared under the optimized conditions. The sorption performance of the developed bacterial biosorbent was 4.36 times greater than that of the raw E. coli. Desorption was carried out using 0.05 M acidified thiourea and the biosorbent was successfully regenerated and reused up to four cycles. Therefore, this simple and cost-effective method suggested here is a useful modification tool for the development of high performance biosorbents for the recovery of anionic precious metals. (C) 2010 Elsevier Ltd. All rights reserved.

Keywords: Adsorption, Aqueous Solution, Binding, Binding Sites, Biomass, Biosorbent, Biosorbents, Biosorption, Biosorption, Biosorption Isotherm, Cadmium, Corynebacterium-Glutamicum, Cost-Effective, Cross-Linked, Design, Desorption, Development, Escherichia, Escherichia Coli, Fermentation, Ions, Isotherm, Iv, Kinetics, Lead, Metals, Methodology, Model, Modification, Modified, Palladium, Performance, Ph, Platinum, Potassium, Potential, Precious Metals, Pt(IV), Recovery, Response Surface Methodology, Rights, Second Order, Second-Order, Solution, Sorption, Sorption Potential, Surface, Surface Modification, Uptake, Waste

? Díaz, V., Ibáñez, R., Gómez, P., Urtiaga, A.M. and Ortiz, I. (2011), Kinetics of electro-oxidation of ammonia-N, nitrites and COD from a recirculating aquaculture saline water system using BDD anodes. Water Research, 45 (1), 125-134.

Full Text: 2011\Wat Res45, 125.pdf

Abstract: The viability of the electro-oxidation technology provided with boron doped diamond (BDD) electrodes for the treatment and reuse of the seawater used in a Recirculating Aquaculture System (RAS) was evaluated in this work. The influence of the applied current density (5-50 A m(-2)) in the removal of Total Ammonia Nitrogen (TAN), nitrite and chemical oxygen demand (COD) was analyzed observing that complete TAN removal together with important reductions of the other considered contaminants could be achieved, thus meeting the requirements for reuse of seawater in RAS systems. TAN removal, mainly due to an indirect oxidation mechanism was described by a second order kinetics while COD and nitrite removal followed zero-th order kinetics. The values of the kinetic constants for the anodic oxidation of each compound were obtained as a function of the applied current density (k(TAN) = 7.86 x 10(-5).exp(6.30 x 10(-2) J); k(NO2) = 3.43 x 10(-2) J; k(COD)= 1.35 x 10(-2) J). The formation of free chlorine and oxidation by-products, i.e., trihalomethanes (THMs) was followed along the electro-oxidation process. Although a maximum concentration of 1.7 mg l(-1) of total trihalomethanes was detected an integrated process combining electrochemical oxidation in order to eliminate TAN, nitrite and COD and adsorption onto activated carbon to remove the residual chlorine and THMs is proposed, as an efficient alternative to treat and reuse the seawater in fish culture systems. Finally, the energy consumption of the treatment has been evaluated. (c) 2010 Elsevier Ltd. All rights reserved.

Keywords: Activated Carbon, Adsorption, Aquaculture Saline Water Reuse, Aqueous-Solution, BDD Anode, By-Products, COD, Culture, Doped Diamond Anodes, Electro-Oxidation, Electrochemical Oxidation, Electrodes, Energy, Fish, Kinetics, Landfill Leachate, Mechanism, Nitrogen Compounds, Oxidation, Oxygen-Demand, Removal, Reuse, Scale-up, Sea-Water, Treatment, Viability, Waste-Water

? Liu, H.J., Yang, F., Zheng, Y.M., Kang, J., Qu, J.H. and Chen, J.P. (2011), Improvement of metal adsorption onto chitosan/Sargassum sp. composite sorbent by an innovative ion-imprint technology. Water Research, 45 (1), 145-154.

Full Text: 2011\Wat Res45, 145.pdf

Abstract: Technology for immobilization of biomass has attracted a great interest due to the high sorption capacity of biomass for sequestration of toxic metals from industrial effluents. However, the currently practiced immobilization methods normally reduce the metal sorption capacities. In this study, an innovative ion-imprint technology was developed to overcome the drawback. Copper ion was first imprinted onto the functional groups of chitosan that formed a pellet-typed sorbent through the granulation with Sargassum sp.; the imprinted copper ion was chemically detached from the sorbent, leading to the formation of a novel copper ion-imprinted chitosan/Sargassum sp. (CICS) composite adsorbent. The copper sorption on CICS was found to be highly pH-dependent and the maximum uptake capacity was achieved at pH 4.7-5.5. The adsorption isotherm study showed the maximum sorption capacity of CICS of 1.08 mmol/g, much higher than the non-imprinted chitosan/Sargassum sp. sorbent (NICS) (0.49 mmol/g). The used sorbent was reusable after being regenerated through desorption. The FTIR and XPS studies revealed that the greater sorption of heavy metal was attributed to the large number of primary amine groups available on the surfaces of the ion-imprinted chitosan and the abundant carboxyl groups on Sargassum sp.. Finally, an intraparticle surface diffusion controlled model well described the sorption history of the sorbents. (c) 2010 Elsevier Ltd. All rights reserved.

Keywords: Biosorption, Copper Removal, Granulation, Ion-Imprinted Chitosan, Sargassum sp., Modified Sargassum Sp, Chitosan Gel Beads, Algal Biomass, Ca-Alginate, Waste-Water, Biosorption, Copper, Removal, Cadmium, Lead

? Kim, E.A., Seyfferth, A.L., Fendorf, S. and Luthy, R.G. (2011), Immobilization of Hg(II) in water with polysulfide-rubber (PSR) polymer-coated activated carbon. Water Research, 45 (2), 453-460.

Full Text: 2011\Wat Res45, 453.pdf

Abstract: An effective mercury removal method using polymer-coated activated carbon was studied for possible use in water treatment. In order to increase the affinity of activated carbon for mercury, a sulfur-rich compound, polysulfide-rubber (PSR) polymer, was effectively coated onto the activated carbon. The polymer was synthesized by condensation polymerization between sodium tetrasulfide and 1,2-dichloroethane in water. PSR-mercury interactions and Hg-S bonding were elucidated from x-ray photoelectron spectroscopy, and Fourier transform infra-red spectroscopy analyses. The sulfur loading levels were controlled by the polymer dose during the coating process and the total surface area of the activated carbon was maintained for the sulfur loading less than 2 wt%. Sorption kinetic studies showed that PSR-coated activated carbon facilitates fast reaction by providing a greater reactive surface area than PSR alone. High sulfur loading on activated carbon enhanced mercury adsorption contributing to a three orders of magnitude reduction in mercury concentration. mu-X-ray absorption near edge spectroscopic analyses of the mercury bound to activated carbon and to PSR on activated carbon suggests the chemical bond with mercury on the surface is a combination of Hg-Cl and Hg-S interaction. The pH effect on mercury removal and adsorption isotherm results indicate competition between protons and mercury for binding to sulfur at low pH. (c) 2010 Published by Elsevier Ltd.

Keywords: Activated Carbon, Adsorption, Bioaccumulation, Bonding, Complexes, Heavy Metal Adsorption, Isotherm, Mercury, Mercury, Molecules, pH, Polysulfide-Rubber Polymer, Removal, Sorption, Spectra, Treatment, X-Ray

? Selvakumar, R., Jothi, N.A., Jayavignesh, V., Karthikaiselvi, K., Antony, G.I., Sharmila, P.R., Kavitha, S. and Swaminathan, K. (2011), As(V) removal using carbonized yeast cells containing silver nanoparticles. Water Research, 45 (2), 583-592.

Full Text: 2011\Wat Res45, 583.pdf

Abstract: The present study involves the development of adsorbent containing silver nanoparticles for arsenate removal using silver reducing property of a novel yeast strain Saccharomyces cerevisiae BU-MBT-CY1 isolated from coconut cell sap. Biological reduction of silver by the isolate was deduced at various time intervals. The yeast cells after biological silver reduction were harvested and subjected to carbonization at 400º C for 1 h and its properties were analyzed using Fourier Transform Infra-Red spectroscopy, X-ray diffraction, scanning electron microscope attached with energy dispersive spectroscopy and transmission electron microscope. The average size of the silver nanoparticles present on the surface of the carbonized silver containing yeast cells (CSY) was 19±9 nm. The carbonized control yeast cells (CCY) did not contain any particles on its surface. As(V) adsorption efficiency of CCY and CSY was deduced in batch mode by varying parameters like contact time, initial concentration, and pH. Desorption studies were also carried out by varying the pH. The experimental data were fitted onto Langmuir and D-R Isotherms and Lagergren and pseudo second order kinetic models. The CSY was more efficient in arsenate removal when compared to CCY. (c) 2010 Elsevier Ltd. All rights reserved.

Keywords: Adsorption, Aqueous-Solution, Arsenic Removal, As(V) Removal, Bioreduction, Characterization, Complex, Desorption, Fungus, Gold Nanoparticles, Iron-Oxide, Isotherm, Isotherms, Kinetics, Langmuir, pH, Saccharomyces cerevisiae, Silver Nanoparticles, Sorption, Water

? Li, L.J., Liu, F.Q., Jing, X.S., Ling, P.P. and Li, A.M. (2011), Displacement mechanism of binary competitive adsorption for aqueous divalent metal ions onto a novel IDA-chelating resin: Isotherm and kinetic modeling. Water Research, 45 (3), 1177-1188.

Full Text: 2011\Wat Res45, 1177.pdf

Abstract: Adsorptive properties for Cu (II), Pb (II) and Cd (II) onto an iminodiacetic acid (IDA) chelating resin were systematically investigated at the optimal pH-value in both single and binary solutions using batch experiments. The Langmuir isotherm model and the pseudo second-order rate equation could explain respectively the isotherm and kinetic experimental data for sole-component system with much satisfaction. The maximum adsorption capacity in single system for Cu (II), Pb (II) and Cd (II) was calculated to be 2.27 mmol/g, 1.27 mmol/g and 0.65 mmol/g individually. The initial adsorption rate followed the order as Cu (II) > Pb (II) > Cd (II) at the fixed initial concentration, and for each metal the initial sorption rate increased as the initial concentration increased. In addition, the modified Langmuir model could describe the binary competitive adsorption behavior successfully, with which the interaction coefficient was obtained to follow the order as Cu (II) < Pb (II) < Cd (II). Furthermore, in every case of the investigated three binary systems, the reduction in both the uptake amounts and distribution coefficients testified the antagonistic competitive phenomena. Obviously, this novel IDA-chelating resin possessed of a good selectivity toward Cu (II) over Pb (II) and Cd (II) for the obtained highest separation factor values were up to 21.30 and 133.91 in the range of tested. This interaction mechanism between the favorable component and other metal ions could mainly contribute to the direct displacement impact which be herewith illustrated schematically. (C) 2010 Elsevier Ltd. All rights reserved.

Keywords: Adsorbent, Adsorption, Behavior, Biosorption, Capacity, Chemical-Modification, Competitive Adsorption, Copper, Cu(II), Displacement Mechanism, Distribution Coefficients, Equilibrium, Exchange, Iminodiacetic Acid Chelating Resin, Impact, Ions, Isotherm, Langmuir Isotherm, Langmuir Model, Mechanism, Metal Ion, Model, Modeling, Modified, Pb(II), pH Value, Pseudo-Second-Order, Selective Removal, Selectivity, Sorption, Uptake

? Matsui, Y., Ando, N., Yoshida, T., Kurotobi, R., Matsushita, T. and Ohno, K. (2011), Modeling high adsorption capacity and kinetics of organic macromolecules on super-powdered activated carbon. Water Research, 45 (4), 1720-1728.

Full Text: 2011\Wat Res45, 1720.pdf

Abstract: The capacity to adsorb natural organic matter (NOM) and polystyrene sulfonates (PSSs) on small particle-size activated carbon (super-powdered activated carbon, SPAC) is higher than that on larger particle-size activated carbon (powdered-activated carbon, PAC). Increased adsorption capacity is likely attributable to the larger external surface area because the NOM and PSS molecules do not completely penetrate the adsorbent particle; they preferentially adsorb near the outer surface of the particle. In this study, we propose a new isotherm equation, the Shell Adsorption Model (SAM), to explain the higher adsorption capacity on smaller adsorbent particles and to describe quantitatively adsorption isotherms of activated carbons of different particle sizes: PAC and SPAC. The SAM was verified with the experimental data of PSS adsorption kinetics as well as equilibrium. SAM successfully characterized PSS adsorption isotherm data for SPACs and PAC simultaneously with the same model parameters. When SAM was incorporated into an adsorption kinetic model, kinetic decay curves for PSSs adsorbing onto activated carbons of different particle sizes could be simultaneously described with a single kinetics parameter value. On the other hand, when SAM was not incorporated into such an adsorption kinetic model and instead isotherms were described by the Freundlich model, the kinetic decay curves were not well described. The success of the SAM further supports the adsorption mechanism of PSSs preferentially adsorbing near the outer surface of activated carbon particles. (C) 2010 Elsevier Ltd. All rights reserved.

Keywords: Activated Carbon, Activated Carbons, Adsorbent, Adsorption, Adsorption Isotherms, Adsorption Kinetics, Capacity, Carbons, Competitive Adsorption, Design, Diffusion, Equilibrium, GAC, Geosmin, Hand, Homogeneous Surface Diffusion Model (HSDM), Isotherm, Isotherm, Isotherms, Kinetics, Matter, Mechanism, Model, Modeling, PAC, Removal, Shell, Success, System, Tests

? Zhang, M., He, F., Zhao, D.Y. and Hao, X.D. (2011), Degradation of soil-sorbed trichloroethylene by stabilized zero valent iron nanoparticles: Effects of sorption, surfactants, and natural organic matter. Water Research, 45 (7), 2401-2414.

Full Text: 2011\Wat Res45, 2401.pdf

Abstract: Zero valent iron (ZVI) nanoparticles have been studied extensively for degradation of chlorinated solvents in the aqueous phase, and have been tested for in-situ remediation of contaminated soil and groundwater. However, little is known about its effectiveness for degrading soil-sorbed contaminants. This work studied reductive dechlorination of trichloroethylene (TCE) sorbed in two model soils (a potting soil and Smith Farm soil) using carboxymethyl cellulose (CMC) stabilized Fe-Pd bimetallic nanoparticles. Effects of sorption, surfactants and dissolved organic matter (DOC) were determined through batch kinetic experiments. While the nanoparticles can effectively degrade soil-sorbed TCE, the TCE degradation rate was strongly limited by desorption kinetics, especially for the potting soil which has a higher organic matter content of 8.2%. Under otherwise identical conditions, similar to 44% of TCE sorbed in the potting soil was degraded in 30 h, compared to similar to 82% for Smith Farm soil (organic matter content = 0.7%). DOG from the potting soil was found to inhibit TCE degradation. The presence of the extracted SOM at 40 ppm and 350 ppm as TOC reduced the degradation rate by 34% and 67%, respectively. Four prototype surfactants were tested for their effects on TCE desorption and degradation rates, including two anionic surfactants known as SDS (sodium dodecyl sulfate) and SDBS (sodium dodecyl benzene sulfonate), a cationic surfactant hexadecyltrimethylammonium (HDTMA) bromide, and a non-ionic surfactant Tween 80. All four surfactants were observed to enhance ICE desorption at concentrations below or above the critical micelle concentration (cmc), with the anionic surfactant SDS being most effective. Based on the pseudo-first-order reaction rate law, the presence of 1xcmc SDS increased the reaction rate by a factor of 2.5 when the nanoparticles were used for degrading TCE in a water solution. SDS was effective for enhancing degradation of ICE sorbed in Smith Farm soil, the presence of SDS at sub-cmc increased TCE degraded by similar to 10%. However, effect of SDS on degradation of TCE in the potting soil was more complex. The presence of SDS at sub-cmc decreased TCE degradation by 5%, but increased degradation by 5% when SDS dosage was raised to 5xcmc. The opposing effects were attributed to combined effects of SDS on TCE desorption and degradation, release of soil organic matter and nanoparticle aggregation. The findings strongly suggest that effect of soil sorption on the effectiveness of Fe-Pd nanoparticles must be taken into account in process design, and soil organic content plays an important role in the overall degradation rate and in the effectiveness of surfactant uses. (C) 2011 Elsevier Ltd. All rights reserved.

Keywords: Aqueous-Solutions, Carboxymethyl Cellulose, Chlorinated Solvents, Contaminated Soil, Dechlorination, Design, Desorption, Effectiveness, Fe-Pd Nanoparticles, Groundwater, Humic-Acid, In-Situ Remediation, Iron, Kinetics, Model, Nanoparticles, Nanoscale Zerovalent Iron, Nonionic Surfactant, Polynuclear Aromatic-Hydrocarbons, Pseudo-First-Order, Remediation, Sodium Dodecyl-Sulfate, Sorption, Surfactant, TCE, Trichloroethylene, Zero Valent Iron

? Ho, Y.S. (2011), Comment on “Adsorption mechanism of selenate and selenite on the binary oxide systems” by Y.T. Chan et al. [Water Research 43 (2009) 4412-4420]. Water Research, 45 (7), 2437.

Full Text: 2011\Wat Res45, 2437.pdf; 2010\Wat Res-Ho1.pdf; 2010\Wat Res-Ho2.pdf

? Dou, X.M., Zhang, Y.S., Wang, H.J., Wang, T.J. and Wang, Y.L. (2011), Performance of granular zirconium-iron oxide in the removal of fluoride from drinking water. Water Research, 45 (12), 3571-3578.

Full Text: 2011\Wat Res45, 3571.pdf

Abstract: In this study, a granular zirconium-iron oxide (GZI) was successfully prepared using the extrusion method, and its defluoridation performance was systematically evaluated. The GZI was composed of amorphous and nano-scale oxide particles. The Zr and Fe were evenly distributed on its surface, with a Zr/Fe molar ratio of similar to 2.3. The granular adsorbent was porous with high permeability potential. Moreover, it had excellent mechanical stability and high crushing strength, which ensured less material breakage and mass loss in practical use. In batch tests, the GZI showed a high adsorption capacity of 9.80 mg/g under an equilibrium concentration of 10 mg/L at pH 7.0, which outperformed many other reported granular adsorbents. The GZI performed well over a wide pH range, of 3.5-8.0, and especially well at pH 6.0-8.0, which was the preferred range for actual application. Fluoride adsorption on GZI followed pseudo-second-order kinetics and could be well described by the Freundlich equilibrium model. With the exception of HCO(3)(-), other co-existing anions and HA did not evidently inhibit fluoride removal by GZI when considering their real concentrations in natural groundwater, which showed that GZI had a high selectivity for fluoride. In column tests using real groundwater as influent, about 370, 239 and 128 bed volumes (BVs) of groundwater were treated before breakthrough was reached under space velocities (SVs) of 0.5, 1 and 3 h^-1, respectively. Additionally, the toxicity characteristic leaching procedure (TCLP) results suggested that the spent GZI was inert and could be safely disposed of in landfill. In conclusion, this granular adsorbent showed high potential for fluoride removal from real groundwater, due to its high performance and physical-chemical properties. (C) 2011 Elsevier Ltd. All rights reserved.

Keywords: Adsorbent, Adsorption, Adsorption-Kinetics, Alumina, Aqueous-Solution, Bone Char, Composite, Defluoridation, Defluoridation, Equilibrium, Ferric Hydroxide GFH, Fluoride, Granular Adsorbent, Kinetics, Model, Performance, Permeability, pH, Pseudo-Second-Order, Sorption, Zirconium-Iron Oxide

? Wick, A., Marincas, O., Moldovan, Z. and Ternes, T.A. (2011), Sorption of biocides, triazine and phenylurea herbicides, and UV-filters onto secondary sludge. Water Research, 45 (12), 3638-3652.

Full Text: 2011\Wat Res45, 3638.pdf

Abstract: The sludge-water distribution of a total of 41 organic micropollutants (9 phenylurea herbicides, 11 triazines, 16 biocides and 5 UV-filters) was investigated in laboratory batch experiments with fresh secondary sludge taken from a municipal WWTP. Sorption kinetics as well as sorption isotherms were examined by analyzing the compound concentration in the aqueous and solid phase for mass balance control and quality assurance. The sorption kinetic experiments revealed a sorption equilibrium time of <2 h and adverse effects of sodium azide on the sludge-water distribution of several compounds. Sorption isotherms were constructed for 6 different spiking levels spanning 3 orders of magnitude (100 ng L(-1)-30,000 ng L(-1)) and were well described by the Freundlich model. For some compounds non-linear sorption with Freundlich exponents n < 1 revealed a decreased sorption affinity to the sludge flocs with increasing aqueous phase concentration. Therefore, sludge-water distribution coefficients (K(d,sec)) were calculated from the isotherm data for a constant concentration level of 1 mu g L(-1). Based on the sludge dry weight (dw), the K(d,sec), values of phenylurea herbicides ranged from 9 L kg(dw) (-1)(sludge) (soproturon) to 320 L kg(dw sludge)(-1) (neburon), those of triazines from 5 L kg(dw) (-1)(sludge) (atrazine) to 190 L kg(dw) (-1)(sludge) (terbutryn), those of biocides from 10 L kg(dw) (-1)(sludge) (N,N-dimethyl-N’-p-tolylsulfamide) to 40,000 L kg(dw) (-1)(sludge) (triclocarban) and those of UV-filters from 9 L kg(dw) (-1)(sludge) (phenylbenzimidazole sulfonic acid) to 720 L kg(dw) (-1)(sludge) (benzophenone-3). For most compounds K(d,sec) values were below 500 L kg(dw) (-1)(sludge) and thus removal in WWTPs by the withdrawal of excess sludge is expected to be negligible (<10%) except for the biocides triclocarban (80-95%), triclosan (55-85%), chlorophene (30-60%), imazalil (25-55%) and fenpropimorph (15-40%) as well as the UV-filter benzophenone-3 (5-20%). A simple linear free-energy relationship (LEER) approach using the logarithmized octanol-water partition coefficient log K(OW) as single descriptor is discussed for a rough classification of nonionic compounds regarding their potential removal in WWTPs by sorption.

Keywords: Activated-Sludge, Adverse Effects, Balance, Beta-Blockers, Biocides, Bisphenol-A, Coefficient K-D, Control, Digested-Sludge, Distribution Coefficients, Equilibrium, Freundlich Isotherms, Isotherm, Isotherms, Kinetics, Model, Musk Fragrances, Phenylurea Herbicides, Quality Assurance, Removal, Secondary Sludge, Sewage-Treatment, Sludge-Water Distribution Coefficients, Sorption, Sorption Isotherms, Sorption Kinetics, Surface Waters, Treatment Plants, Triazines, UV-Filters, Waste-Water Treatment

? Morisada, S., Rin, T., Ogata, T., Kim, Y.H. and Nakano, Y. (2011), Adsorption removal of boron in aqueous solutions by amine-modified tannin gel. Water Research, 45 (13), 4028-4034.

Full Text: 2011\Wat Res45, 4028.pdf

Abstract: A tannin gel (TG) synthesized from condensed tannin molecules has a remarkable ability to adsorb various metal ions in aqueous solutions. In the present study, the adsorption removal of boron in solutions at various pHs and temperatures has been examined using the TG and the amine-modified tannin gel (ATG) prepared with ammonia treatment of the TG. The adsorption amounts of boron for the TG and the ATG were relatively small and almost constant below pH 7, whereas the boron adsorption amounts increased with increasing pH in the range of pH above 7. Considering that in aqueous solutions above pH 7, the mole fraction of boric acid decreases while that of tetrahydroxyborate ion increases with increasing pH, the boron adsorption onto both gels takes place probably through the chelate formation of tetrahydroxyborate ion with the hydroxy and the amino groups in the gels. Besides, the adsorbability of the ATG for boron was higher than that of the TG due to the stable coordination bond between boron and nitrogen of the amino group in the ATG. The adsorption kinetics were adequately described by the pseudo-second order kinetic equation while the adsorption isotherms followed both the Langmuir and the Freundlich equations. The boron adsorbability of both the TG and the ATG at low boron concentration were comparable or fairly good compared with other adsorbents. (C) 2011 Elsevier Ltd. All rights reserved.

Keywords: Adhesives, Adsorption, Adsorption Isotherms, Adsorption Kinetics, Amine Modification, Batch Adsorption, Boron Removal, Freundlich, Gels, Ion-Exchange, Isotherms, Kinetic, Kinetics, Langmuir, Mechanism, Natural Condensed Tannin, Performance, pH, Redox, Removal, Resin, Sorption, Tannin Gel, Water, Water Treatment

? Gupta, V.K., Gupta, B., Rastogi, A., Agarwal, S. and Nayak, A. (2011), Pesticides removal from waste water by activated carbon prepared from waste rubber tire. Water Research, 45 (13), 4047-4055.

Full Text: 2011\Wat Res45, 4047.pdf

Abstract: Waste rubber tire has been used for the removal of pesticides from waste water by adsorption phenomenon. By applying successive chemical and thermal treatment, a basically cabonaceous adsorbent is prepared which has not only a higher mesopore, macropore content but also has a favorable surface chemistry. Presence of oxygen functional groups as evidenced by FTIR spectra along with excellent porous and surface properties were the driving force for good adsorption efficiency observed for the studied pesticides: methoxychlor, methyl parathion and atrazine. Batch adsorption studies revealed maximum adsorption of 112.0 mg g(-1), 104.9 mg g(-1) and 88.9 mg g(-1) for methoxychlor, atrazine and methyl parathion respectively occurring at a contact time of 60 min at pH 2 from an initial pesticide concentration of 12 mg/L. These promising results were confirmed by column experiments; thereby establishing the practicality of the developed system. Effect of various operating parameters along with equilibrium, kinetic and thermodynamic studies reveal the efficacy of the adsorbent with a higher adsorption capacity than most other adsorbents. The adsorption equilibrium data obey Langmuir model and the kinetic data were well described by the pseudo-first-order model. Applicability of Bangham's equation indicates that diffusion of pesticide molecules into pores of the adsorbent mainly controls the adsorption process. Spontaneous, exothermic and random characteristics of the process are confirmed by thermodynamic studies. The developed sorbent is inexpensive in comparison to commercial carbon and has a far better efficiency for pesticide removal than most other adsorbents reported in literature. (C) 2011 Elsevier Ltd. All rights reserved.

Keywords: Activated Carbon, Adsorbent, Adsorbents, Adsorption, Adsorption Isotherm, Aqueous-Solution, Atrazine, Bagasse Fly-Ash, Capacity, Char, Diffusion, Driving, Efficacy, Equilibrium, FTIR, Functional, Kinetics, Langmuir Model, Literature, Methoxychlor, Methyl Parathion, Model, Peat, Pesticides, pH, Pseudo-First-Order, Pyrolysis, Removal, Sorption, Sugar-Industry Waste, Treatment, Waste, Waste Rubber Tire

? Carabineiro, S.A.C., Thavorn-Amornsri, T., Pereira, M.F.R. and Figueiredo, J.L. (2011), Adsorption of ciprofloxacin on surface-modified carbon materials. Water Research, 45 (15), 4583-4591.

Full Text: 2011\Wat Res45, 4583.pdf

Abstract: The adsorption capacity of ciprofloxacin (CPX) was determined on three types of carbon-based materials: activated carbon (commercial sample), carbon nanotubes (commercial multi-walled carbon nanotubes) and carbon xerogel (prepared by the resorcinol/formaldehyde approach at pH 6.0). These materials were used as received/prepared and functionalised through oxidation with nitric acid. The oxidised materials were then heat treated under inert atmosphere (N(2)) at different temperatures (between 350 and 900 degrees C). The obtained samples were characterised by adsorption of N(2) at -196 degrees C, determination of the point of zero charge and by temperature programmed desorption. High adsorption capacities ranging from approximately 60 to 300 mg(CPx) g(C)(-1) were obtained (for oxidised carbon xerogel, and oxidised thermally treated activated carbon Norit ROX 8.0, respectively). In general, it was found that the nitric acid treatment of samples has a detrimental effect in adsorption capacity, whereas thermal treatments, especially at 900 degrees C after oxidation, enhance adsorption performance. This is due to the positive effect of the surface basicity. The kinetic curves obtained were fitted using 1st or 2nd order models, and the Langmuir and Freundlich models were used to describe the equilibrium isotherms obtained. The 2nd order and the Langmuir models, respectively, were shown to present the best fittings. (C) 2011 Elsevier Ltd. All rights reserved.

Keywords: Activated Carbon, Activated Carbons, Adsorption, Antibiotics, Aqueous-Solutions, Aromatic-Compounds, Capacity, Carbon Nanotubes, Carbon Xerogel, Chemistry, Ciprofloxacin, Degradation, Desorption, Equilibrium, Fluoroquinolone Antibacterial Agents, Isotherms, Langmuir and Freundlich Models, Multiwalled Carbon Nanotubes, Nanotubes, Oxidation, Ozonation, pH, Treatment, Waste-Water