Personal Research Database

Full Text: 2007\J Haz Mat144, 200.pdf

Abstract: In this study experiments were conducted to investigate the adsorption of 2,4-dichlorophenol (2,4-DCP) by activated carbon fiber (ACF) activated by static air. With the results of batch experiments at various temperatures, the adsorption isotherms, kinetics and thermodynamics of this adsorption process were evaluated. Four adsorption isotherm models, Langmuir, Freundlich, Redlich-Peterson and Toth equations, were used to fit the experimental data and the results reveal that the adsorption isotherm models fitted the data in the order of: Langmuir > Redlich-Peterson > Toth > Freundlich isotherms. A pseudo second-order adsorption model was better to describe the adsorption data than the pseudo first-order model and the Bangham model at the temperatures tested. The activation energy was calculated to be 40.90 kJ/mol, while the thermodynamic parameters ΔH and ΔS were estimated to be −5.82 kJ/mol and 0.07 kJ/(mol K), respectively.

Keywords: 2,4-DCP, 2,4-Dichlorophenol, ACF, Activated Carbon, Activated Carbon Fiber, Activation, Activation Energy, Adsorption, Adsorption Characteristics, Adsorption Isotherm, Adsorption Isotherm Models, Adsorption Isotherms, Adsorption Model, Adsorption Process, Air, Aqueous Solutions, Batch, Batch Experiments, Biosorption, Carbon, Characteristics, Chlorophenols, Coir Pith, Contaminants, Energy, Equations, Equilibrium, Experimental, Experimental Data, First Order, Freundlich, Freundlich Isotherms, Isotherm, Isotherm Models, Isotherms, Kinetics, Langmuir, Model, Models, Order, Parameters, Phenols, Pith Carbon, Process, Pseudo First-Order, Pseudo Second Order, Pseudo Second-Order, Pseudo-First-Order, Pseudo-Second-Order, Redlich-Peterson, Removal, Second Order, Solutions, Static, Surface, Temperatures, Thermodynamic, Thermodynamic Parameters, Thermodynamics, Water

? Altundogan, H.S., Bahar, N., Mujde, B. and Tumen, F. (2007), The use of sulphuric acid-carbonization products of sugar beet pulp in Cr(VI) removal. Journal of Hazardous Materials, 144 (1-2), 255-264.

Full Text: 2007\J Haz Mat144, 255.pdf

Abstract: A carbon rich adsorbent prepared from the reaction of sugar beet pulp with sulphuric acid and gas formed during carbonization process have been studied for Cr(VI) removal from aqueous solutions. The SO₂ rich gas was shown to be an excellent Cr(VI) reductant. The equilibrium and kinetic studies were conducted by using the carbonaceous adsorbent derived from sugar beet pulp. The lower pH favoured Cr(VI) adsorption but substantial Cr(VI) reduction was observed. The Langmuir and Freundlich isotherm models were applied and the Langmuir model best fit the equilibrium isotherm data. The maximum adsorption capacity of chromium calculated from Langmuir isotherm is about 24 mg g⁻¹ for 25 °C. The adsorption of Cr(VI) is an endothermic process and follows the pseudo-second-order rate kinetics. The sulphuric acid-carbonization is an economical method for particularly chromium removal because the gas generated during carbonization exhibits good Cr(VI) reduction properties and carbonaceous material obtained is an efficient Cr(VI) adsorbent.

Keywords: Acid, Activated Carbon, Adsorbent, Adsorption, Adsorption Capacity, Aqueous Solutions, Aqueous-Solution, Binding-Capacity, Capacity, Carbon, Carbonaceous, Carbonaceous Adsorbent, Carbonaceous Material, Carbonization, Chromium, Chromium Removal, Cr(VI), Cr(VI) Adsorption, Cr(VI) Reduction, Cr(VI) Removal, Divalent Metal-Cations, Endothermic, Equilibrium, Equilibrium Isotherm, Freundlich, Freundlich Isotherm, Heavy Metal Removal, Hexavalent Chromium, Ion-Exchange Properties, Isotherm, Isotherm Data, Isotherm Models, Kinetic, Kinetic Studies, Kinetics, Langmuir, Langmuir and Freundlich Isotherm, Langmuir Isotherm, Langmuir Model, Langmuir-Isotherm, Model, Models, Paper-Manufacture, pH, Process, Products, Properties, Pseudo Second Order, Pseudo-Second-Order, Pulp, Rate, Reaction, Reductant, Reduction, Removal, Shell Activated Carbon, SO₂, Solutions, Sugar, Sugar Beet Pulp, Sulphuric Acid, Waste-Water

? Mullett, M., Tardio, J., Bhargava, S. and Dobbs, C. (2007), Removal of mercury from an alumina refinery aqueous stream. Journal of Hazardous Materials, 144 (1-2), 274-282.

Full Text: 2007\J Haz Mat144, 274.pdf

Abstract: Digestion condensate is formed as a by-product of the alumina refinery digestion process. The solution exhibits a high pH and is chemically reducing, containing many volatile species such as water, volatile organics, ammonia, and mercury. Because digestion condensate is chemically unique, an innovative approach was required to investigate mercury removal. The mercury capacity and adsorption kinetics were investigated using a number of materials including gold, silver and sulphur impregnated silica and a silver impregnated carbon. The results were compared to commercial sorbents, including extruded and powdered virgin activated carbons and a sulphur impregnated mineral. Nano-gold supported on silica (88% removal under batch conditions and 95% removal under flow conditions) and powdered activated carbon (91% under batch conditions and 98% removal under flow conditions) were the most effective materials investigated. The silver and sulphur impregnated materials were unstable in digestion condensate under the test conditions used.

Keywords: Mercury, Process Water, Alumina Refining

? Bulut, Y., Gözübenli, N. and Aydın, H. (2007), Equilibrium and kinetics studies for adsorption of direct blue 71 from aqueous solution by wheat shells. Journal of Hazardous Materials, 144 (1-2), 300-306.

Full Text: 2007\J Haz Mat144, 300.pdf

Abstract: This paper deals with the application of wheat shells (WS), an agricultural by-product, for the removal of direct blue 71 (DR) from aqueous solution. The characteristics of WS surface, such as surface area, Bohem titration and scanning electron microscopy (SEM) were obtained. The removal of direct blue 71 onto WS from aqueous solution was investigated by using parameters, such as pH, temperature, adsorbent dose, contact time and initial concentration. The adsorption process attains equilibrium within 36 h. The extent of dye removal decreased with increasing adsorbent dosage and also increased with increasing contact time, temperature, in solution concentration. Optimum pH value for dye adsorption was determined between 6 and 8. The experimental data were analysed by the Langmuir and Freundlich models of adsorption. It was found that the Langmuir equation fit better than the Freundlich equation. Maximum adsorption capacity (Qm) was calculated as at different temperatures (293, 303 and 313 K) 40.82, 45.66 and 46.30 mg g⁻¹, respectively. In addition, the adsorption data obtained at different temperatures of DR by WS were applied to pseudo first-order, pseudo second-order and Weber–Morris equations, and the rate constants of first-order adsorption (k1), the rate constants of second-order adsorption (k2) and intraparticle diffusion rate constants (k3) at these temperatures were calculated, respectively. The rates of adsorption were found to conform to pseudo second-order kinetics with good correlation (R2 ≥ 0.9904). Also, free energy of adsorption (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) changes were determined to predict the nature of adsorption. Furthermore, the results indicate that WS could be employed as a low-cost alternative to other adsorbents in the removal of direct blue 71 from aqueous solution.

Keywords: Adsorbent, Adsorbent Dosage, Adsorbents, Adsorption, Adsorption Capacity, Adsorption Process, Agricultural, Agricultural By-Product, Anionic Dyes, Aqueous Solution, Bran, By-Product, Capacity, Characteristics, Concentration, Congo Red, Constants, Contact Time, Correlation, Diffusion, Direct Dyes, Direct Red, Dosage, Dye, Dye Adsorption, Dye Removal, Dyes, Electron Microscopy, Energy, Enthalpy, Entropy, Equations, Equilibrium, Experimental, Experimental Data, First Order, Free Energy, Free Energy Of Adsorption, Freundlich, Freundlich Equation, Hull, Intraparticle Diffusion, Kinetics, Langmuir, Langmuir Equation, Methylene-Blue, Microscopy, Models, Paper, Parameters, pH, Predict, Process, Pseudo First-Order, Pseudo Second Order, Pseudo Second Order Kinetics, Pseudo Second-Order, Pseudo Second-Order Kinetics, Pseudo-First-Order, Pseudo-Second-Order, Rate, Rate Constants, Removal, Sawdust, Scanning Electron Microscopy, Second Order, Second Order Kinetics, Second-Order Kinetics, SEM, Shells, Surface, Surface Area, Temperature, Temperatures, Thermodynamics, Titration, Waste-Water, Wheat, Wheat Shells

? Kuleyin, A. (2007), Removal of phenol and 4-chlorophenol by surfactant-modified natural zeolite. Journal of Hazardous Materials, 144 (1-2), 307-315.

Full Text: 2007\J Haz Mat144, 307.pdf

Abstract: In this study the adsorption characteristics of phenol and 4-chlorophenol by surfactant-modified zeolite was investigated. Batch studies were performed to evaluate the effects of various experimental parameters such as contact time, adsorbent dose, initial concentration, and temperature on the removal of phenol and 4-chlorophenol. The sorption kinetics was tested for intraparticle diffusion, Elovich, and pseudo-second order reaction and rate constants of kinetic models were calculated. Equilibrium isotherms for the adsorption of phenol were analyzed by Freundlich, Langmuir, and Tempkin isotherm models. Freundlich isotherm was found to best represent the data for phenol and 4-chlorophenol adsorption.

Keywords: 4-Chlorophenol, Activated Carbon, Adsorbent, Adsorption, Adsorption Characteristics, Aqueous-Solutions, Bentonite, Characteristics, Chromate, Clinoptilolite, Concentration, Constants, Contact Time, Diffusion, Effects, Elovich, Equilibrium, Experimental, Freundlich, Freundlich Isotherm, Hexadecyltrimethylammonium, Intraparticle Diffusion, Isotherm, Isotherm Models, Isotherms, Kinetic, Kinetic Models, Kinetics, Langmuir, Models, Modification, Natural, Natural Zeolite, Order, Parameters, Phenol, Pseudo Second Order, Pseudo-Second Order, Pseudo-Second-Order, Rate, Rate Constants, Reaction, Removal, Removal Of Phenol, Sorption, Sorption, Sorption Kinetics, Temperature, Waste-Water, Zeolite

? Weng, C.H. and Pan, Y.F. (2007), Adsorption of a cationic dye (methylene blue) onto spent activated clay. Journal of Hazardous Materials, 144 (1-2), 355-362.

Full Text: 2007\J Haz Mat144, 355.pdf

Abstract: The adsorption characteristics of methylene blue (MB) onto spent activated clay (SAC), a waste produced from an edible oil manufacturer was investigated. Results showed that the adsorption increased with increasing MB concentration, temperature, and pH. The adsorption equilibrium data was well fitted by multilayer adsorption isotherm. The maximum adsorption capacities for MB ranged from 0.94×10⁻⁴ to 3.41×10⁻⁴ mol/g between 5 and 45 °C. Thermodynamic parameters suggest that the adsorption is spontaneous and endothermic. We proposed a modified double exponential equation accounting both with chemical and mathematical point of view to describe the adsorption kinetic data. The increases of mass transfer and adsorption capacity were mainly attributed to the interlayer of the SAC expanding at higher temperature. An activation energy of 13.5 kcal/K mol was determined suggesting that the adsorption involved a chemical reaction mechanism.

Keywords: Adsorption, Dye, Spent Activated Clay, Methylene Blue

? Unuabonah, E.I., Adebowale, K.O. and Olu-Owolabi, B.I. (2007), Kinetic and thermodynamic studies of the adsorption of lead(II) ions onto phosphate-modified kaolinite clay. Journal of Hazardous Materials, 144 (1-2), 386-395.

Full Text: 2007\J Haz Mat144, 386.pdf

Abstract: This study is on the kinetics and thermodynamics of the adsorption of Pb²⁺ onto phosphate-modified and unmodified kaolinite clay obtained from Ubulu-Ukwu in Delta State of Nigeria. Increasing initial Pb²⁺ concentration increased the rate of Pb²⁺ adsorbed with increase in initial Pb²⁺ concentration from 300 to 1000 mg/L. Increasing Pb²⁺ concentration also increased the initial sorption rate h, from 1.404 to 13.11 mg g⁻¹ min⁻¹ for phosphate-modified kaolinite clay and 1.04–3.48 for unmodified kaolinite clay as Pb²⁺ concentration. Increase in temperature was found to increase the initial sorption rate of Pb²⁺ adsorption onto phosphate-modified adsorbent from 3.940 to 8.85 and 2.55 to 4.16 mg g⁻¹ min⁻¹ for the unmodified adsorbent. The overall sorption rate k, increased only slightly from 5.1×10⁻² to 9.7×10⁻² g mg⁻¹ min⁻¹ for phosphate-modified adsorbent, 3.8×10⁻² to 5.4×10⁻² g mg⁻¹ min⁻¹ for unmodified adsorbent. The adsorption reaction on both adsorbents was found to be chemically activated reaction and endothermic with energy of activation, E, at 500 mg/L of Pb²⁺ in solution as 19 and 10.68 kJ mol⁻¹ for phosphate-modified and unmodified adsorbents, respectively. The positive values of both ΔH° and ΔS° obtained suggest an endothermic reaction and in increase in randomness at the solid–liquid interface during the adsorption of Pb²⁺ onto the adsorbents. ΔG° values obtained were all negative indicating a spontaneous adsorption process. The presence of Cd²⁺ decreased both initial sorption rate and the amount of Pb²⁺ adsorbed on phosphate-modified and unmodified adsorbents at equilibrium. The adsorption process follows a pseudo-second-order reaction scheme.

Keywords: Activation, Activation Energy, Adsorbent, Adsorbents, Adsorption, Adsorption Process, Aqueous-Solution, Cd²⁺, Clay, Concentration, Endothermic, Energy, Equilibrium, Interface, Kaolinite, Kaolinite Clay, Kaolmite, Kinetics, Lead, Metal Removal, Methylene-Blue, Nickel, Nigeria, Pb, Pb²⁺, Pb²⁺ Adsorption, pH, Phosphate-Modified, Process, Pseudo Second Order, Pseudo-Second-Order, Rate, Reaction, Reaction Scheme, Sorption, Sorption Rate, Sphagnum Moss Peat, Spontaneous, Temperature, Thermodynamic, Thermodynamic Studies, Thermodynamics

? Álvarez, P., Blanco, C. and Granda, M. (2007), The adsorption of chromium(VI) from industrial wastewater by acid and base-activated lignocellulosic residues. Journal of Hazardous Materials, 144 (1-2), 400-405.

Full Text: 2007\J Haz Mat144, 400.pdf

Abstract: This study deals with the adsorption of Cr(VI) from synthetic and industrial wastewater, produced by a sewage plant. The activated carbons were prepared from a lignocellulosic raw material by thermal treatment at 450 and 650 °C in the presence of acid (AlCl₃, HCl, H₃PO₄ and H₂SO₄) and base (NaOH) agents. To optimize the adsorption of Cr(VI), the chemical modifications caused by each activating agent (related to the capability of Cr(VI) removal), and the optimal experimental conditions of the pH, Cr(VI) concentration, adsorbent dose and residence time, were studied. Thus, treatment with H₃PO₄ gives rise to carbons with a high surface area and high efficiency for Cr(VI) removal at short equilibrium times. In contrast, the generation of active surface sites by means of NaOH requires longer equilibrium times, the adsorption being less effective than in the former case. The adsorption isotherms obey the Langmuir equation only in the first stages of the reaction but fit the Freundlich equations over the whole range studied, so the heat of adsorption can be easily calculated. The results also show that the activated carbons obtained can be recovered by filtration with an efficiency of 30% in the third cycle.

Keywords: Sawdust, Acidic Treatment, Basic Treatment, Cr(VI), Adsorption

? Huang, Y.H., Hsueh, C.L., Cheng, H.P., Su, L.C. and Chen, C.Y. (2007), Thermodynamics and kinetics of adsorption of Cu(II) onto waste iron oxide. Journal of Hazardous Materials, 144 (1-2), 406-411.

Full Text: 2007\J Haz Mat144, 406.pdf

Abstract: This study investigates low-cost sorbents as replacements for current costly methods of removing heavy metals from solution. This investigation explores the waste iron oxide material (F1), which is a by-product of the fluidized-bed reactor (FBR)–Fenton reaction, for use in the treatment of the wastewater in Taiwan. X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the F1. In this investigation, F1 are tested as adsorbents for removing copper (Cu²⁺) from aqueous solutions. The highest Cu²⁺ adsorption capacity of F1 adsorbent was determined as 0.21 mmol g⁻¹ for 0.8 mmol dm⁻³ initial Cu²⁺ concentration at pH 6.0 and 300 K. Adsorption data were well described by the Freundlich model and the thermodynamic constants of the adsorption process, ΔG°, ΔH° and ΔS° were evaluated as −6.12 kJ mol⁻¹ (at 318 K), 9.2 kJ mol⁻¹ and 48.19 J mol⁻¹ K⁻¹ (at 318 K), respectively. Additionally, a pseudo-second-order rate model was adopted to describe the kinetics of adsorption.

Keywords: Activated Carbon, Adsorbent, Adsorbents, Adsorption, Adsorption Capacity, Adsorption Process, Aqueous Solutions, Aqueous-Solutions, By-Product, Cadmium, Capacity, Catalytic-Oxidation, Concentration, Constants, Copper, Copper, Cu(II), Cu²⁺, Cu²⁺ Adsorption Capacity, Current, Electron Microscopy, Fluidized Bed, Fluidized Bed Reactor, Fluidized-Bed Reactor, Freundlich, Freundlich Model, Goethite, Heavy Metals, Heavy-Metals, Investigation, Iron, Iron Oxide, Kinetics, Kinetics of Adsorption, Low-Cost Sorbents, Metals, Methods, Microscopy, Model, Oxide, pH, Powder, Process, Pseudo Second Order, Pseudo-Second-Order, Rate, Rate Model, Reaction, Reactor, Removal, Scanning Electron Microscopy, Sem, Solutions, Sorbents, Taiwan, Thermodynamic, Treatment, Waste, Wastewater, Water, XRD

? Fernandes, A.N., Almeida, C.A.P., Menezes, C.T.B., Debacher, N.A. and Sierra, M.M.D. (2007), Removal of methylene blue from aqueous solution by peat. Journal of Hazardous Materials, 144 (1-2), 412-419.

Full Text: 2007\J Haz Mat144, 412.pdf

Abstract: In this study, the removal of methylene blue (MB) from aqueous solution by peat was analyzed. The peat was collected from a peatland at Arroio do Silva Beach, in Santa Catarina state, in the south of Brazil. Adsorption was conducted using varied initial concentrations of the MB solutions and three different temperatures (35, 45 and 60 °C). An adsorption time of around 4.5 h was sufficient to reach the equilibrium for all temperatures, in the concentration range studied. Percentage removal was greater for diluted solutions, but the absolute amount of MB adsorbed by the peat at equilibrium increased with an increase of the initial concentration, corroborating the efficacy of the material as an adsorbent. Temperature influenced slightly the reaction, which was endothermic. Results indicated a multi-layered process and the data were analyzed considering pseudo-first-order, pseudo-second-order and intraparticle diffusion approaches. The latter two mechanisms seem to be significant in the rate-controlling step.

Keywords: Adsorbent, Adsorption, Adsorption Time, Aqueous Solution, Basic-Dyes, Brazil, Concentration, Concentrations, Copper, Diffusion, Dye Adsorption, Efficacy, Endothermic, Equilibrium, Intraparticle Diffusion, Isotherms, Kinetic Parameters, Kinetics, Mb, Mechanisms, Methylene Blue, Model, Peat, Peatland, Process, Pseudo Second Order, Pseudo-First-Order, Pseudo-Second-Order, Range, Reaction, Removal, Solutions, Sorption, Temperatures, Textile Effluent, Waste-Water

? Mondal, P., Balomajumder, C. and Mohanty, B. (2007), A laboratory study for the treatment of arsenic, iron, and manganese bearing ground water using Fe³⁺ impregnated activated carbon: Effects of shaking time, pH and temperature. Journal of Hazardous Materials, 144 (1-2), 420-426.

Full Text: 2007\J Haz Mat144, 420.pdf

Abstract: This paper deals with the experimental investigation related to removal of arsenic from a simulated contaminated ground water by the adsorption onto Fe³⁺ impregnated granular activated carbon (GAC-Fe) in presence of Fe²⁺, Fe³⁺, and Mn²⁺. Similar study has also been done with granular activated carbon (GAC) for comparison. The effects of shaking time, pH, and temperature on the percentage removal of As(T), As(III), As(V), Fe²⁺, Fe³⁺, and Mn have been discussed. The shaking time for optimum removal of arsenic species has been noted as 8 h for GAC-Fe and 12 h for GAC, respectively. As(T) removal was less affected by the change in pH within the pH range of 2–11. Maximum removal of As(V) and As(III) was observed in the pH range of 5–7 and 9–11, respectively, for both the adsorbents. Under the experimental conditions at 30 °C, the optimum removal of As(T), As(III), As(V), Fe, and Mn are 95.5%, 93%, 98%, 100%, and 41%, respectively, when GAC-Fe is used. For GAC these values are 56%, 41%, 71%, 99%, and 98%. The adsorbent dose (AD) and its particle size (PS) for both GAC and GAC-Fe were 30 g/l and 125–150 μm, respectively. The initial arsenic concentration in the synthetic water sample was 200 ppb.

Keywords: Arsenic, GAC, Iron-Impregnated Activated Carbon, Surface-Modified Adsorbent, Ground Water

? Afkhami, A., Madrakian, T. and Karimi, Z. (2007), The effect of acid treatment of carbon cloth on the adsorption of nitrite and nitrate ions. Journal of Hazardous Materials, 144 (1-2), 427-431.

Full Text: 2007\J Haz Mat144, 427.pdf

Abstract: The effects of functional groups on the adsorption efficiency of nitrate and nitrite from water by carbon cloth were investigated. The carbon cloth was treated by sulfuric acid and used for the adsorption of nitrate and nitrite from water samples at nearly neutral solutions. The concentrations of ions in the solution were monitored using in situ UV spectroscopy. Acid treatment caused a significant increase in the adsorption rate of ions and the adsorption capacity of the adsorbent.

Keywords: Activated Carbon, Surface Treatment, Adsorption, Nitrate, Nitrite, Adsorption Capacity

? Karadağ, D., Koç, Y., Turan, M. and Öztürk, M. (2007), A comparative study of linear and non-linear regression analysis for ammonium exchange by clinoptilolite zeolite. Journal of Hazardous Materials, 144 (1-2), 432-437.

Full Text: 2007\J Haz Mat144, 432.pdf

Abstract: Ammonium ion exchange from aqueous solution using clinoptilolite zeolite was investigated at laboratory scale. Batch experimental studies were conducted to evaluate the effect of various parameters such as pH, zeolite dosage, contact time, initial ammonium concentration and temperature. Freundlich and Langmuir isotherm models and pseudo-second-order model were fitted to experimental data. Linear and non-linear regression methods were compared to determine the best fitting of isotherm and kinetic model to experimental data. The rate limiting mechanism of ammonium uptake by zeolite was determined as chemical exchange. Non-linear regression has better performance for analyzing experimental data and Freundlich model was better than Langmuir to represent equilibrium data.

Keywords: Adsorption, Ammonium, Ammonium Uptake, Analysis, Aqueous Solution, Aqueous-Solution, Chemical, Clinoptilolite, Clinoptilolite Zeolite, Comparative Study, Concentration, Contact Time, Dosage, Equilibrium, Equilibrium Data, Experimental, Experimental Data, Fitting, Freundlich, Freundlich Model, Ion, Ion Exchange, Ion-Exchange, Isotherm, Isotherm Models, Kinetic, Kinetic Model, Langmuir, Langmuir Isotherm, Langmuir-Isotherm, Linear, Linear and Nonlinear Regression, Mechanism, Methods, Model, Models, Natural Zeolite, Non-Linear, Non-Linear Regression, Nonlinear, Nonlinear Regression, Packed-Bed, Parameters, Performance, pH, Pseudo Second Order, Pseudo-Second-Order, Pseudo-Second-Order Model, Rate, Rate Limiting, Regression, Regression Analysis, Removal, Scale, Sorption, Systems, Temperature, Uptake, Waste, Zeolite

? Bayramoğlu, G. and Arıca, M.Y. (2007), Kinetics of mercury ions removal from synthetic aqueous solutions using by novel magnetic p(GMA-MMA-EGDMA) beads. Journal of Hazardous Materials,