Personal Research Database

Full Text: 2009\J Haz Mat164, 1019.pdf

Abstract: The ability of Sargassurn sp. to biosorb four metal ions, namely lead, copper, zinc, and manganese from a synthetic multi-solute system and real storm water runoff has been investigated for the first time. Experiments on synthetic multi-solute systems revealed that Sargassurn performed well in the biosorption of all four metal ions, with preference towards Pb, followed by Cu, Zn, and Mn. The solution pH strongly affected the metal biosorption, with pH 6 being identified as the optimal condition for achieving maximum biosorption. Experiments at different biosorbent dosages revealed that good biosorption capacity as well as high metal removal efficiency was observed at 3 g/L The biosorption kinetics was found to be fast with equilibrium being attained within 50 min. According to the Langmuir isotherm model, Sargassum exhibited maximum uptakes of 214, 67.5. 24.2 and 20.2 mg/g for lead, copper, zinc, and manganese, respectively in single-solute systems. In multi-metal systems, strong competition between four metal ions in terms of occupancy binding sites was observed, and Sargassum showed preference in the order of Pb > Cu > Zn > Mn. The application of Sargassum to remove four heavy metal ions in real storm water runoff revealed that the biomass was capable of removing the heavy metal ions. However, the biosorption performance was slightly lower compared to that of synthetic metal solutions. Several factors were responsible for this difference, and the most important factor is the presence of other contaminants such as anions, organics, and other trace metals in the runoff. (C) 2008 Elsevier B.V. All rights reserved.

Keywords: Acid, Adsorption, Biosorption, Biosorption, Copper(II), Equilibrium, Heavy Metal, Isotherm, Kinetics, Sargassum, Storm Water Runoff, Water Treatment

? Li, Y.J., Gao, B.Y., Wu, T., Wang, B. and Li, X. (2009), Adsorption properties of aluminum magnesium mixed hydroxide for the model anionic dye Reactive Brilliant Red K-2BP. Journal of Hazardous Materials, 164 (2-3), 1098-1104.

Full Text: 2009\J Haz Mat164, 1098.pdf

Abstract: The use of aluminum magnesium mixed metal hydroxide (MMH) as adsorbent to remove Reactive Brilliant Red K-2BP (RBR K-2BP), as a model anionic dye, from aqueous solution was investigated. MMH was prepared by coprecipitation and was characterized by XRD, TEM and average particle diameter. Adsorption experiments were carried out as a function of pH, contact time, concentration of dye, adsorbent dosage, and temperature. The results showed that MMH was particularly effective to remove RBR K-2BP, and that the effective pH range for the dye removal was between 4.0 and 11.0, but at pHs lower than 4, dissolution of MMH took place. A significant decline of dye adsorption occurred at pHs above the isoelectric point (IEP). The adsorption of RBR K-2BP on MMH reached equilibrium within 4 h. The appropriate adsorbent dosage was 1000mg/L The interaction between the surface sites of MMH and the dye ions may be a combination of both anion exchange and surface complexation. Three kinetic models have been evaluated to fit the experimental data. It was shown that the pseudo-second-order model best described the adsorption kinetics of RBR K-2BP on MMH. The equilibrium isotherm showed that the adsorption of RBR K-2BP onto MMH was consistent with the Langmuir and Freundlich equations. and the saturated adsorption capacity of MMH for RBR K-2BP was 657.5 mg/g. The adsorption process was endothermic in nature. MMH displayed superior treatment efficiency to the industrial dye effluents from a printing and dyeing plant with a removal efficiency of 93.8-96.7% for colored materials and 77.9-83.6% for COD. (C) 2008 Published by Elsevier B.V.

Keywords: Activated Carbon, Adsorption, Adsorption Isotherm, Aqueous-Solution, Chemical Coagulation, Dye, Equilibrium, Fly-Ash, Hydrotalcite-Like Compounds, Kinetics, Layered Double Hydroxides, Mixed Metal Hydroxide, Removal, Textile Effluent, Waste-Water

? Ahn, C.K., Park, D., Woo, S.H. and Park, J.M. (2009), Removal of cationic heavy metal from aqueous solution by activated carbon impregnated with anionic surfactants. Journal of Hazardous Materials, 164 (2-3), 1130-1136.

Full Text: 2009\J Haz Mat164, 1130.pdf

Abstract: To increase their capacity to adsorb heavy metals, activated carbons were impregnated with the anionic surfactants sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS), or dioctyl sulfosuccinate sodium (DSS). Surfactant-impregnated activated carbons removed Cd(II) at up to 0.198 mmol g^-1, which was more than an order of magnitude better than the Cd(II) removal performance of activated carbon without surfactant (i.e., 0.016 mmol g^-1) even at optimal pH (i.e., pH 6). The capacity of the activated carbon to adsorb Cd(II) increased in proportion to the quantity of surfactant with which they were impregnated. The kinetics of the adsorption of Cd(H) onto the surfactant-impregnated activated carbon was best described by a pseudo-second-order model, and was described better by the Freundlich adsorption isotherm than by the Langmuir isotherm. The surface charge of activated carbon was negative in all pH ranges tested (2-6). These results indicate that surface modification with anionic surfactant could be used to significantly enhance the capacity of activated carbon to adsorb cations. (C) 2008 Published by Elsevier B.V.

Keywords: Activated Carbon, Adsorbents, Adsorption, Anionic Surfactant, Arsenate, Cadmium, Cadmium Ion Adsorption, Cd(II), Component, Hexavalent Chromium, Impregnation, Lead, Models, Oxidation, Removal, Sorption, Waste-Water

? Royer, B., Cardoso, N.F., Lima, E.C., Vaghetti, J.C.P., Simon, N.M., Calvete, T. and Veses, R.C. (2009), Applications of Brazilian pine-fruit shell in natural and carbonized forms as adsorbents to removal of methylene blue from aqueous solutions-Kinetic and equilibrium study. Journal of Hazardous Materials, 164 (2-3), 1213-1222.

Full Text: 2009\J Haz Mat164, 1213.pdf

Abstract: The Brazilian pine-fruit shell (Araucaria angustifolia) is a food residue, which was used in natural and carbonized forms, as low-cost adsorbents for the removal of methylene blue (MB) from aqueous solutions. Chemical treatment of Brazilian pine-fruit shell (PW), with sulfuric acid produced a non-activated carbonaceous material (C-PW). Both PW and C-PW were tested as low-cost adsorbents for the removal of MB from aqueous effluents. It was observed that C-PW leaded to a remarkable increase in the specific surface area, average porous volume, and average porous diameter of the adsorbent when compared to PW. The effects of shaking time, adsorbent dosage and pH on adsorption capacity were studied. In basic pH region (pH 8.5) the adsorption of MB was favorable. The contact time required to obtain the equilibrium was 6 and 4h at 25°C, using PW and C-PW as adsorbents, respectively. Based on error function values (F-error) the kinetic data were better fitted to fractionary-order kinetic model when compared to pseudo-first order, pseudo-second order, and chemisorption kinetic models. The equilibrium data were fitted to Langmuir, Freundlich, Sips and Redlich-Peterson isotherm models. For MB dye the equilibrium data were better fitted to the Sips isotherm model using PW and C-PW as adsorbents. (C) 2008 Elsevier B.V. All rights reserved.

Keywords: Activated Carbon, Adsorption, Araucaria-Angustifolia Wastes, Basic Dye, Batch Conditions, Biosorption, Brazilian Pine-Fruit Shell, Low-Cost Adsorbent, Mandarin Peels, Methylene Blue, Nonlinear Isotherms, Statistical Design, Thin Chitosan Membranes, Unburned Carbon, Yellow Passion-Fruit

? Liu, G.F., Ma, J., Li, X.C. and Qin, Q.D. (2009), Adsorption of bisphenol A from aqueous solution onto activated carbons with different modification treatments. Journal of Hazardous Materials, 164 (2-3), 1275-1280.

Full Text: 2009\J Haz Mat164, 1275.pdf

Abstract: Two commercial carbons (W20 and F20) had been selectively modified with nitric acid and thermal treatment under a flow of N-2 in present study to adsorb bisphenol A from aqueous solution. The results indicated that the experimental data were well described with pseudo-second-order kinetic model. W20 and its thermal modified sample (W20N) represented a better adsorption capacity, and the equilibrium adsorption amounts reached 382.12 and 432.34 mg/g, respectively. Further, effects of temperature, pH and ionic strength on bisphenol A adsorption onto W20 and W20N had been examined. It was found that the adsorbed amount of bisphenol A decreased with the increase of temperature from 288 to 318 K and changed little with the increase of pH from 5.0 to 9.0. At pH 11.0, the two activated carbons represented the weakest adsorption capacity. The adsorption capacities of bisphenol A onto W20 and W20N first decreased and then increased with the increasing of ionic strength. (C) 2008 Elsevier B.V. All rights reserved.

Keywords: Activated Carbon, Adsorption, Bisphenol A, Endocrine Disrupting Chemicals, Equilibrium, Estradiol, Exposure, Kinetics, Kinetics, Modification, Organic Waste, Oxidation, Removal, Water

? Feng, N.C., Guo, X.Y. and Liang, S. (2009), Adsorption study of copper(II) by chemically modified orange peel. Journal of Hazardous Materials, 164 (2-3), 1286-1292.

Full Text: 2009\J Haz Mat164, 1286.pdf

Abstract: An adsorbent, the chemically modified orange peel, was prepared from hydrolysis of the grafted copolymer, which was synthesized by interaction of methyl acrylate with cross-linking orange peel. The presence of poly (acrylic acid) on the biomass surface was verified by infrared spectroscopy (IR), scanning electron microscopy (SEM) and thermogravimetry (TG). Total negative charge in the biomass surface and the zeta potentials were determined. The modified biomass was found to present high adsorption capacity and fast adsorption rate for Cu (II). From Langmuir isotherm, the adsorption capacity for Cu (II) was 289.0 mg g^-1, which is about 6.5 times higher than that of the unmodified biomass. The kinetics for Cu (II) adsorption followed the pseudo-second-order kinetics. The adsorbent was used to remove Cu (II) from electroplating wastewater and was suitable for repeated use for more than four cycles. (C) 2008 Elsevier B.V. All rights reserved.

Keywords: Activated Carbon, Adsorption, Aqueous-Solution, Biosorption, Copper Ion, Equilibrium, Heavy-Metals, Ions, Isotherm, Kinetics, Modified Orange Peel Adsorbent, Removal, Sorption, Thermodynamic Parameters, Waste-Water

? Sarı, A. and Tuzen, M. (2009), Biosorption of As(III) and As(V) from aqueous solution by macrofungus (Inonotus hispidus) biomass: Equilibrium and kinetic studies. Journal of Hazardous Materials, 164 (2-3), 1372-1378.

Full Text: 2009\J Haz Mat164, 1372.pdf

Abstract: The biosorption characteristics of As(III) and As(V) from aqueous solution using the macrofungus (Inonotus hispidus) biomass were investigated as a function of pH, biomass dosage, contact time, and temperature. Langmuir, Freundlich and Dubinin-Radush kevich (D-R) models were applied to describe the biosorption isotherm of the metal ions by I. hispidus biomass. Langmuir model fitted the equilibrium data better than the Freundlich isotherm. The biosorption capacity of I. hispidus for As(III) and As(V) was found to be 51.9 mg/g and 59.6 mg/g, respectively at optimum conditions of pH 6 for As(III) and pH 2 for As(V), contact time of 30 min and temperature of 20C. The metal ions were desorbed from I. hispidus using both 1 M HCl and 1 M HNO₃. The high stability of I. hispidus permitted 10 times of adsorption-elution process along the studies with a decrease about 11-28% in recovery of As(III) and 10-25% for As(V). The mean free energy values evaluated from the D-R model indicated that the biosorption of As(III) and As(V) onto I. hispidus biomass was taken place by chemical ion-exchange. The calculated thermodynamic parameters showed that the biosorption of As(III) and As(V) ions onto L hispidus biomass was feasible, spontaneous and exothermic under examined conditions. Kinetic examination of the experimental data were showed that the biosorption processes of both As(III) and As(V) followed well pseudo-second-order kinetics. (C) 2008 Elsevier B.V. All rights reserved.

Keywords: Adsorption Characteristics, Arsenic Removal, As(III), As(V), Biosorbent, Biosorption, Botrytis-Cinerea, Chelating Resin, Drinking-Water, Inonotus Hispidus, Iron, Kinetic, Macrofungus, Metal-Ions, Rhizopus-Oryzae, Sorption

? Arslanoglu, H., Altundogan, H.S. and Tumen, F. (2009), Heavy metals binding properties of esterified lemon. Journal of Hazardous Materials, 164 (2-3), 1406-1413.

Full Text: 2009\J Haz Mat164, 1406.pdf

Abstract: Sorption of Cd²⁺, Cr³⁺, Cu²⁺, Ni²⁺, Pb²⁺ and Zn²⁺ onto a carboxyl groups-rich material prepared from lemon was investigated in batch systems. The results revealed that the sorption is highly pH dependent. Sorption kinetic data indicated that the equilibrium was achieved in the range of 30-240 min for different metal ions and sorption kinetics followed the pseudo-second-order model for all metals studied. Relative sorption rate of various metal cations was found to be in the general order of Ni²⁺ > Cd²⁺ > Cu²⁺ > Pb²⁺ > Zn²⁺ > Cr³⁺. The binding characteristics of the sorbent for heavy metal ions were analyzed under various conditions and isotherm data was accurately fitted to the Langmuir equation. The metal binding capacity order calculated from Langmuir isotherm was Pb²⁺ > Cu²⁺ > Ni²⁺ > Cd²⁺ > Zn²⁺ > Cr³⁺. The mean free energy oftnetal sorption process calculated from Dubinin-Radushkevich parameter and the Polanyi potential was found to be in the range of 8-11 kJ mol^-1 for the metals studied showing that the main mechanism governing the sorption process seems to be ion exchange. The basic thermodynamic parameters of metals ion sorption process were calculated by using the Langmuir constants obtained from equilibration study. The ΔG°and ΔH° values for metals ion sorption on the lemon sorbent showed the process to be spontaneous and exothermic in nature. Relatively low ΔH° values revealed that physical adsorption significantly contributed to the mechanism. (C) 2008 Elsevier B.V. All rights reserved.

Keywords: Adsorption, Aqueous-Solution, Citric-Acid, Heavy Metal, Ion-Exchange Properties, Kinetics, Lemon, Low-Cost Adsorbents, Modified Rice Husk, Removal, Sorption, Sorption Characteristics, Thermodynamics, Waste, Water

? Kastner, J.R., Miller, J. and Das, K.C. (2009), Pyrolysis conditions and ozone oxidation effects on ammonia adsorption in biomass generated chars. Journal of Hazardous Materials, 164 (2-3), 1420-1427.

Full Text: 2009\J Haz Mat164, 1420.pdf

Abstract: Ammonia adsorbents were generated via pyrolysis of biomass (peanut hulls and palm oil shells) over a range of temperatures and compared to a commercially available activated carbon (AC) and solid biomass residuals (wood and poultry litter fly ash). Dynamic ammonia adsorption studies (i.e., breakthrough curves) were performed using these adsorbents at 23 degrees C from 6 to 17 ppmv NH3. Of the biomass chars, palm oil char generated at 500 degrees C had the highest NH3 adsorption capacity (0.70 mg/g, 6 ppmv, 10% relative humidity (RH)), was similar to the AC, and contrasted to the other adsorbents (including the AC), the NH3 adsorption capacity significantly increased if the relative humidity was increased (4 mg/g, 7 ppmv, 73% RH). Room temperature ozone treatment of the chars and activated carbon significantly increased the NH3 adsorption capacity (10% RH); resultant adsorption capacity, q (mg/g) increased by similar to 2,6, and 10 times for palm oil char, peanut hull char (pyrolysis only), and activated carbon, respectively. However, water vapor (73% RH at 23 degrees C) significantly reduced NH3 adsorption capacity in the steam and ozone treated biomass, yet had no effect on the palm shell char generated at 500 degrees C. These results indicate the feasibility of using a low temperature (and thus low energy input) pyrolysis and activation process for the generation of NH3 adsorbents from biomass residuals. (C) 2008 Elsevier B.V. All rights reserved.

Keywords: Activated Carbon, Activated Carbon, Activation, Adsorbents, Adsorption, Adsorption Capacity, Ammonia, Biomass, Breakthrough, Capacity, Carbon, Char, Charcoal, Dynamic, Emissions, Fixed-Bed, Fly Ash, Fly-Ash, Humidity, Litter, NH3, NH3 Adsorption, Organics, Oxidation, Ozone, Ozone Activation, Palm Shell, Process, Pyrolysis, Removal, Temperature, Treatment, Water, Water Vapor, Wood

? Vasudevan, S., Lakshmi, J., Jayaraj, J. and Sozhan, G. (2009), Remediation of phosphate-contaminated water by electrocoagulation with aluminium, aluminium alloy and mild steel anodes. Journal of Hazardous Materials, 164 (2-3), 1480-1486.

Full Text: 2009\J Haz Mat164, 1480.pdf

Abstract: The present study provides an electrocoagulation process for the remediation of phosphate-contaminated water using aluminium, aluminium alloy and mild steel as the anodes and stainless steel as the cathode. The various parameters like effect of anode materials, effect of pH, concentration of phosphate, current density, temperature and co-existing ions, and so forth, and the adsorption capacity was evaluated using both Freundlich and Langmuir isotherm models. The adsorption of phosphate preferably fitting the Langmuir adsorption isotherm suggests monolayer coverage of adsorbed molecules. The results showed that the maximum removal efficiency of 99% was achieved with aluminium alloy anode at a current density of 0.2 A dm², at a pH of 7.0. The adsorption process follows second-order kinetics. (C) 2008 Elsevier B.V. All rights reserved.

Keywords: Adsorption, Aluminium Alloy Anode, Aqueous-Solutions, Blast-Furnace Slags, Coagulation, Electrocoagulation, Electrodes, Electrolysis, Equilibrium, Industrial Solid-Waste, Isotherm, Kinetics, Phosphate, Phosphorus Removal, Speciation

? Gozmen, B., Turabik, M. and Hesenov, A. (2009), Photocatalytic degradation of Basic Red 46 and Basic Yellow 28 in single and binary mixture by UV/TiO₂/periodate system. Journal of Hazardous Materials, 164 (2-3), 1487-1495.

Full Text: 2009\J Haz Mat164, 1487.pdf

Abstract: The present study deals with the investigation of photocatalytic degradation and mineralization of C.I. Basic Red 46 (BR46) and C.I. Basic Yellow 28 (BY28) dyes in single and binary solutions as a function of periodate ion concentration (1041, irradiation time, initial pH and initial dye concentrations. First order derivative spectrophotometric method was used for to simultaneous analysis of BY28 and BR46 in binary mixtures. Langmuir-Hinshelwood kinetic model was applied to experimental data and apparent reaction rate constant values were calculated. The apparent degradation rate constant values of BR46 were higher than those of BY28 for all experiments in single dye solutions. On the other hand, the significant reductions were observed for the apparent degradation rate constant values of the BR46 in the presence of BY28 in binary solutions whereas TOC removal efficiency slightly enhanced in binary system. The highest TOC removal efficiency was obtained at pH 3.0 by adding 5 mM periodate ion in to the solution in the presence of 1 g/L TiO(2) for both dye solutions. After 3 h illumination, 68, 76 and 75% mineralization were found for 100 mg/L BY28, 100 mg/L BR46 and 50 + 50 mg/L mixed solutions, respectively. (C) 2008 Elsevier B.V. All rights reserved.

Keywords: Activated Carbon, Adsorption, Analysis, Aqueous TiO₂ Suspensions, Azo-Dye, Basic Red, Basic Red 46, Binary Mixture, Decolorization, Derivative Spectrophotometry, Experimental, Hand, Kinetic, Kinetic Model, Model, Periodate, pH, Photoactivated Periodate, Photocatalytic, Photocatalytic Degradation, Rate Constant, Reactive Dye, Removal, Spectrophotometry, TiO₂, TOC, Uv-Irradiation, Waste-Water

? Gong, J.L., Wang, B., Zeng, G.M., Yang, C.P., Niu, C.G., Niu, Q.Y., Zhou, W.J. and Liang, Y. (2009), Removal of cationic dyes from aqueous solution using magnetic multi-wall carbon nanotube nanocomposite as adsorbent. Journal of Hazardous Materials, 164 (2-3), 1517-1522.

Full Text: 2009\J Haz Mat164, 1517.pdf

Abstract: A magnetic multi-wall carbon nanotube (MMWCNT) nanocomposite was synthesized and was used as an adsorbent for removal of cationic dyes from aqueous solutions. The MMWCNT nanocomposite was composed of commercial multi-wall carbon nanotubes and iron oxide nanoparticles. The properties of this magnetic adsorbent were characterized by scanning electron microscopy, X-ray diffraction and BET surface area measurements. Adsorption characteristics of the MMWCNT nanocomposite adsorbent were examined using methylene blue. neutral red and brilliant cresyl blue as adsorbates. Experiments were carried out to investigate adsorption kinetics, adsorption capacity of the adsorbent and the effect of adsorption dosage and solution pH values on the removal of cationic dyes. Kinetic data were well fitted by a pseudo second-order model. Freundlich model was used to study the adsorption isotherms. The prepared MMWCNT adsorbent displayed the main advantage of separation convenience compared to the present adsorption treatment. (C) 2008 Elsevier B.V. All rights reserved.

Keywords: Adsorption, Adsorption, Chitosan, Dye, Equilibrium, Extractant, Kinetic, Kinetics, Magnetic Separation, Multi-Wall Carbon Nanotube, Nanoparticles, Oxidation, Particles, Removal, Wastewaters, Water

? Chabani, M., Amrane, A. and Bensmaili, A. (2009), Equilibrium sorption isotherms for nitrate on resin Amberlite IRA 400. Journal of Hazardous Materials, 165 (1-3), 27-33.

Full Text: 2009\J Haz Mat165, 27.pdf

Abstract: The adsorption isotherms of nitrate on resin Amberlite IRA 400 at various pH, in the range 2-12, were experimentally determined by batch tests. The experimental data have been analysed using the Langmuir, Freundlich, Redlich-Peterson and Sips isotherms models. In order to determine the best fit isotherm, two error analysis methods were used to evaluate the data: the regression correlation coefficient, and the statistic Chi-square test. In the range of pH tested, the Sips model was found to give the best fit of the adsorption isotherm data. The maximum adsorption capacity can be deduced from the obtained correlation coefficients and was found to decrease for increasing pH. (C) 2008 Elsevier B.V. All rights reserved.

Keywords: Adsorption Isotherm, Adsorption-Isotherm, Chitosan, Lead, Metal-Ions, Models, Nitrate, Peat, Removal, Resin

? Amin, N.K. (2009), Removal of direct blue-106 dye from aqueous solution using new activated carbons developed from pomegranate peel: Adsorption equilibrium and kinetics. Journal of Hazardous Materials, 165 (1-3), 52-62.

Full Text: 2009\J Haz Mat165, 52.pdf

Abstract: The use of cheap, high efficiency and ecofriendly adsorbent has been studied as an alternative source of activated carbon for the removal of dyes from wastewater. This study investigates the use of activated carbons prepared from pomegranate peel for the removal of direct blue dye from aqueous solution. A series of experiments were conducted in a batch system to assess the effect of the system variables, i.e. initial pH, temperature, initial dye concentration adsorbent dosage and contact time. The results showed that the adsorption of direct blue dye was maximal at pH 2, as the amount of adsorbent increased, the percentage of dye removal increased accordingly but it decreased with the increase in initial dye concentration and solution temperature. The adsorption kinetics was found to follow pseudo-second-order rate kinetic model, with a good correlation (R-2 > 0.99) and intra-particle diffusion as one of the rate determining steps. Laingmuir, Freundlich, Temkin, Dubinin-RadushKevich (D-R) and HarkinS-Jura isotherms were used to analyze the equilibrium data at different temperatures. In addition, Various thermodynamic parameters, such as standard Gibbs free energy (ΔG degrees), standard enthalpy (ΔH degrees), standard entropy (ΔS degrees), and the activation energy (E-a) have been calculated. The adsorption process of direct blue dye onto different activated carbons prepared from pomegranate peel was found to be spontaneous and exothermic process. The findings of this investigation suggest that the physical sorption plays a role in controlling the sorption rate. (C) 2008 Elsevier B.V. All rights reserved.

Keywords: Acid Dyes, Activated Carbon, Adsorption, Bagasse-Fly-Ash, Congo Red, Direct Blue-106 Dye, Intra-Particle Diffusion, Isotherm Analyses, Mechanism, Methylene-Blue, pH, Reactive Dye, Removal, Rice-Husk, Solid-Waste, Thermodynamic Parameters, Waste-Water

? Eren, E. (2009), Removal of lead ions by Unye (Turkey) bentonite in iron and magnesium oxide-coated forms. Journal of Hazardous Materials,