Personal Research Database

Full Text: 2006\J Haz Mat138, 409.pdf

Abstract: The objective of this study is to remove the congo red (CR) anionic dye, from water by using the acid activated red mud in batch adsorption experiments. The effects of contact time, pH, adsorbent dosage and initial dye concentration on the adsorption were investigated. The pH of the dye solution strongly affected the chemistry of both the dye molecules and activated red mud in an aqueous solution. The effective pH was 7.0 for adsorption on activated red mud. It was found that the sufficient time to attain equilibrium was 90 min. The adsorption isotherms were analyzed using the Langmuir, the Freundlich, and the three parameter Redlich–Peterson isotherms. The Langmuir isotherm was the best-fit adsorption isotherm model for the experimental data obtained from the non-linear chi-square statistic test.

Keywords: Activated Red Mud, Congo Red, Adsorption, Isotherm, Chi-Square Test

? Pamukoğlu, M.Y. and Kargi, F. (2006), Batch kinetics and isotherms for biosorption of copper(II) ions onto pre-treated powdered waste sludge (PWS). Journal of Hazardous Materials, 138 (3), 479-484.

Full Text: 2006\J Haz Mat138, 479.pdf

Abstract: Waste sludge samples from different plants were tested for Cu(II) ion biosorption capacities with and without pre-treatment. Waste sludge from a paint industry wastewater treatment plant was found to perform better than the others after pre-treatment with 1% H₂O₂. Powdered waste sludge (PWS) from the paint industry wastewater treatment plant was used for recovery of Cu(II) ions from aqueous solution by biosorption after pre-treatment with 1% H₂O₂. Batch kinetics and isotherms of biosorption of Cu(II) ions were investigated at variable initial Cu(II) concentrations between 50 and 400 mg l⁻¹ with a PWS particle size of 64 μm. The pseudo-first and -second order kinetic models were used to correlate the experimental data. The kinetic constants were determined for both models and the second order kinetic model was found to be more suitable. The Langmuir, Freundlich and the generalized isotherm models were used to correlate the equilibrium biosorption data and the isotherm constants were determined. The Langmuir isotherm was found to fit the experimental data better than the other isotherms tested. The maximum biosorption capacity (116 mg g⁻¹) of the pre-treated powdered waste sludge for Cu(II) ions was found to be superior as compared to the other biosorbents reported in literature

Keywords: Aqueous Solution, Biosorbents, Biosorption, Capacity, Copper(II), Copper(II) Ions, Cu(II), Cu(II) Ion, Cu(II) Ions, Data, Equilibrium, Experimental, Freundlich, Isotherm, Isotherms, Kinetic, Kinetic Model, Kinetic Models, Kinetics, Langmuir, Langmuir Isotherm, Literature, Model, Models, Particle Size, Plant, Plants, Powdered Waste Sludge (PWS), Pre-Treatment, Pretreatment, Pseudo-First and, Recovery, Second Order, Second-Order, Size, Sludge, Solution, Treatment, Waste, Waste Sludge, Wastewater, Wastewater Treatment, Wastewater Treatment Plant

? Beltrán, F.J., Rodriguez, E.M. and Romero, M.T. (2006), Kinetics of the ozonation of muconic acid in water. Journal of Hazardous Materials, 138 (3), 534-538.

Full Text: 2006\J Haz Mat138, 534.pdf

Abstract: The removal of muconic acid (specifically trans-trans-butanedioc acid) with ozone from water has been studied for kinetics purposes. Concentrations of muconic acid of 4.410^-4 M are completely removed with ozone in less than 14 and 9 min at pH 3 and 7, respectively, and 310^-4 M of ozone in the gas. The positive influence of pH was due to the more reactive muconic acid dissociated form with ozone. The process can be described as a second order irreversible gas-liquid reaction developing in the moderate kinetic regime of absorption. At the experimental conditions investigated no free radical reactions are present and muconic acid is entirely oxidized by molecular ozone. Rate constants of the direct reaction between muconic acid and ozone were found to be 1.610⁴ and 1.410⁵ M^-1 s^-1 at 20C, pH 3 and 7, respectively, according to film theory. (c) 2006 Elsevier B.V. All rights reserved.

Keywords: Ozone, Muconic Acid, Ozonation Kinetics, Water Pollution, Kinetic Modeling, Aqueous-Solutions, Ozone, Solubility, Toxicity, Phenols

? Wang, X.S. and Qin, Y. (2006), Removal of Ni(II), Zn(II) and Cr(VI) from aqueous solution by Alternanthera philoxeroides biomass. Journal of Hazardous Materials, 138 (3), 582-588.

Full Text: 2006\J Haz Mat138, 582.pdf

Abstract: Alternanthera philoxeroides biomass, a type of freshwater macrophyte, was used for the sorptive removal of Ni(II), Zn(II) and Cr(VI) from aqueous solutions. Variables of the batch experiments include solution pH, contact time, particle size and temperature. The biosorption capacities are significantly affected by solution pH. Higher pH favors higher Ni(II), Zn(II) removal, whereas higher uptake of Cr(VI) is observed as the pH is decreased. A two-stage kinetic behavior is observed in the biosorption of Ni(II), Zn(II) and Cr(VI): very rapid initial biosorption in a few minutes, followed by a long period of a slower uptake. It is noted that an increase in temperature results in a higher Ni(II), Zn(II) and Cr(VI) loading per unit weight of the sorbent. Decreasing the particle sizes of the Alternanthera philoxeroides biomass leads to an increase in the Ni(II), Zn(II) and Cr(VI) uptake per unit weight of the sorbent. All isothermal data are fairly well fitted with Langmuir equations. The thermodynamic parameter, ΔG°, were calculated. The negative ΔG° values of Cr(VI), Ni(II) and Zn(II) at various temperatures confirm the adsorption processes are spontaneous.

Keywords: Activated Carbon, Adsorption, Alternanthera Philoxeroides Biomass, Aqueous Solution, Aqueous Solutions, Bagasse Fly-Ash, Batch, Batch Experiments, Behavior, Biomass, Biosorption, Contact, Copper, Cr(VI), Data, Equilibrium, Experiments, Freshwater, Ions, Isothermal, Kinetic, Langmuir, Langmuir Isotherm, Lead, Loading, Ni(II), Ni(II), Particle Size, pH, Rapid, Removal, Rights, Size, Solution, Solutions, Sorbent, Spontaneous, Sugar-Industry Waste, Temperature, Thermodynamic, Thermodynamic Parameter, Time, Uptake, Values, Water, Weight, Zinc, Zn(II)

? Zhang, D.Y., Wang, J.L. and Pan, X.L. (2006), Cadmium sorption by EPSs produced by anaerobic sludge under sulfate-reducing conditions. Journal of Hazardous Materials, 138 (3), 589-593.

Full Text: 2006\J Haz Mat138, 589.pdf

Abstract: This study showed that EPS produced by anaerobic sludge under sulfate-reducing bacteria was effective in removing Cd²⁺ from solution. The sorption data could be described by the Freundlich isotherm model. The q_m derived from the Langmuir isotherm model was up to 2720 mg/g EPSs. The presence of copper and nickel ions had significantly reduced the cadmium sorption by EPS and the presence of zinc had little effect. Analysis of FTIR spectra demonstrated that C–O–C of polysaccharides at 1150–1030 cm⁻¹, group of the amide(I), CH₂ group of the lipids, carboxyl and –OH groups of proteins and polysaccharides were involved in cadmium binding, of which the –OH groups and the C–O–C group of polysaccharides played a major role in cadmium sorption by EPSs.

Keywords: Anaerobic Sludge, Extracellular Polymeric Substances, Cadmium, Biosorption

? Nadeem, M., Mahmood, A., Shahid, S.A., Shah, S.S., Khalid, A.M. and McKay, G. (2006), Sorption of lead from aqueous solution by chemically modified carbon adsorbents. Journal of Hazardous Materials, 138 (3), 604-613.

Full Text: 2006\J Haz Mat138, 604.pdf

Abstract: An indigenously prepared, steam activated and chemically modified carbon from husk and pods of Moringa oleifera (M.oleifera), an agricultural waste, was comparatively examined as an adsorbent for the removal of lead from aqueous solutions. Studies were conducted as a function of contact time, initial metal concentration, dose of adsorbent, agitation speed, particle size, and pH. Maximum uptake capacities were found to be, 98.89, 96.58, 91.8, 88.63, 79.43% for cetyltrimethyl ammonium bromide (CTAB), phosphoric, sulfuric, hydrochloric acid treated and untreated carbon adsorbents respectively. Bangham, Pseudo-first and second order, Intra Particle Diffusion equations were implemented to express the sorption mechanism by utilized adsorbents. Adsorption rate of lead ions was found to be considerably faster for chemically modified adsorbents than unmodified. The results of adsorption were fitted to both the Langmuir and Freundlich models. Satisfactory agreement between the metal uptake capacities by the adsorbents at different time intervals was expressed by the correlation coefficient (R²). The Langmuir model represented the sorption process better than the Freundlich one, with R² values ranging from 0.994 to 0.998.

Keywords: Activated Carbon, Activated Carbon, Adsorbent, Adsorbents, Adsorption, Adsorption, Adsorption Isotherms, Adsorption Rate, Agitation, Agricultural, Agricultural Waste, Ammonium, Aqueous Solution, Aqueous Solutions, Bromide, Carbon, Chemical Modification, Concentration, Contact, Copper, Correlation, Correlation Coefficient, CTAB, Diffusion, Equilibrium, Freundlich, Function, Heavy-Metals, Intervals, Intra-Particle Diffusion, Intraparticle, Intraparticle Diffusion, Ions, Kinetics, Langmuir, Langmuir Model, Lead, Mechanism, Metal, Metal Uptake, Model, Models, Modified, Modified Adsorbents, Modified Carbon, Moringa Oleifera, Particle Size, pH, Process, Removal, Rice Husk, Rights, Second Order, Second-Order, Size, Sludge, Solution, Solutions, Sorption, Sorption Mechanism, Sorption Process, Speed, Steam, Time, Uptake, Values, Waste, Waste-Water

? Kumar, K.V. and Porkodi, K. (2006), Relation between some two- and three-parameter isotherm models for the sorption of methylene blue onto lemon peel. Journal of Hazardous Materials, 138 (3), 633-635.

Full Text: 2006\J Haz Mat138, 633.pdf

Abstract: Equilibrium uptake of methylne blue onto lemon peel was fitted to the 2 two-parameter isotherm models namely Freundlich and Langmuir and 3 six-parameter isotherm models namely Redlich–Peterson, Toth, Radke–Prausnitz, Fritz–Schluender, Vieth–Sladek and Sips isotherms by non-linear method. A comparison between two-parameter and three-parameter isotherms was reported. The best fitting isotherm was the Sips isotherm followed by Langmuir isotherm and Redlich–Peterson isotherm equation. Redlich–Peterson isotherm is a special case of Langmuir isotherm when the Redlich–Peterson isotherm constant g was unity. Radke–Prausnitz, Toth, Vieth–Sladek isotherm were the same when the Toth isotherm constant, n_T and the Radke–Prausnitz isotherm, m_RP are equal to unity and when the Vieth–Sladek isotherm constant, K_VS equals zero. The sorption capacity of lemon peel for methylene blue uptake was found to be 29 mg/g.

Keywords: Adsorption, Methylene Blue, Lemon Peel, Isotherms, Two-Parameter Isotherms, Three-Parameter Isotherms

? Katsoyiannis, I.A. (2007), Carbonate effects and pH-dependence of uranium sorption onto bacteriogenic iron oxides: Kinetic and equilibrium studies. Journal of Hazardous Materials, 139 (1), 31-37.

Full Text: 2007\J Haz Mat139, 31.pdf

Abstract: The removal of U(VI) from groundwaters by adsorption onto bacteriogenic iron oxides (BIOS) has been investigated under batch mode. The adsorbent dosage, the uranium concentration, the concentration of carbonate and the use of a real groundwater spiked with uranium comprised the examined parameters. In addition, the effect of pH was examined in two different water matrixes, i.e., in distilled water and in real groundwater. Equilibrium studies were carried out to determine the maximum adsorption capacity of BIOS and the data correlated well with the Langmuir and Freundlich models. The presence of carbonate affected adversely the adsorption of U(VI) onto BIOS. The maximum adsorption capacity of BIOS was 9.25 mg g⁻¹ at 0.1 mM carbonate concentration and decreased to 6.93 mg g⁻¹ at 0.5 mM carbonate concentration, whereas at carbonate concentration of 2 mM practically no adsorption occurred. The data were further analyzed using the pseudo-second order kinetic equation, which fitted best the experimental results. The initial adsorption rate (h) was found to increase with decreasing the concentration of carbonate in all cases. When experiments were accomplished in the absence of carbonate, the pH values did not have an effect on the adsorption of U(VI). However, the extent of U(VI) adsorption was strongly pH-dependent when the experiments were carried out in the real groundwater. The maximum adsorption capacity increased sharply as the pH decreased and optimum removal was obtained in the pH range 3.2–4.0, thus bacteriogenic iron oxides can found application in the removal of U(VI) by adsorption from low pH or low carbonate waters.

Keywords: Adsorbent, Adsorption, Adsorption, Adsorption Capacity, Adsorption Rate, Aqueous-Solution, Capacity, Carbonate, Concentration, Dosage, Effects, Equilibrium, Freundlich, Groundwater, Initial Adsorption Rate, Iron, Iron Oxides, Kinetic, Langmuir, Models, Oxides, Parameters, pH, pH Dependence, pH Values, Pseudo-Second Order, Pseudo-Second-Order, Range, Removal, Sorption, Subsurface Media, Subterranean Environment, U(VI), Uranium, Uranyl, Water, Waters

? Singh, B., Prasad, G.K., Mahato, T.H. and Sekhar, K. (2007), Breakthrough behavior of diethyl sulphide vapor on active carbon systems. Journal of Hazardous Materials, 139 (1), 38-43.

Full Text: 2007\J Haz Mat139, 38.pdf

Abstract: Breakthrough behavior of diethyl sulphide vapors on carbon systems such as active carbon, NaOH/CrO₃/C, NaOH/CrO₃/EDA/C and RuCl₃/C has been studied by using modified Wheeler equation and the same was used to calculate the pseudo-first-order rate constant (k(v)) and kinetic saturation of capacity (W,) values. Effects of various parameters such as bed height, air flow rate, concentration and temperature on the above parameters have also been studied. Rate constant was found to be increasing with air flow rate, while W, was found to be invariable. Both kv and W, decreased with the increase in temperature, however, no significant effect on W, and kv was observed due to concentration change. The values of kinetic saturation capacity were used to predict the service lives/breakthrough times of carbon beds (when used in filtration systems). (c) 2006 Elsevier B.V. All rights reserved.

Keywords: Active Carbon, Adsorption, Adsorption Properties, Air, Air Flow, Air Mixtures, Behavior, Breakthrough Time, Capacity, Carbon, Concentration, Diethyl Sulphide, Filtration, Flow, Gas Adsorption, Impregnated Carbons, Kinetic, Kinetics, Modified, Modified Active Carbon, Parameters, Predict, Rate Constant, Saturation, Sulfur Mustard, Sulphide, Temperature

? Arthanareeswaran, G., Thanikaivelan, P., Jaya, N., Mohan, D. and Raajenthiren, M. (2007), Removal of chromium from aqueous solution using cellulose acetate and sulfonated poly(ether ether ketone) blend ultrafiltration membranes. Journal of Hazardous Materials, 139 (1), 44-49

Full Text: 2007\J Haz Mat139, 44.pdf

Abstract: A process for purifying aqueous solutions containing heavy and toxic metals such as chromium has been investigated. Chromium salts are largely used in various industries including leather-manufacturing industry. Ultrafiltration processes are largely being applied for macromolecular and heavy metal ion separation from aqueous streams. Cellulose acetate and sulfonated poly(ether ether ketone) blend ultrafiltration membranes were prepared by precipitation phase inversion technique in 100/0, 90/10, 80/20 and 70/30% polymer blend compositions and subjected to the rejection of chromium at different concentrations such as 200, 400, 600, 800 and 1000 ppm with a water-soluble macroligand (polyvinylalcohol). Factors affecting the percentage rejection and permeate flux such as pH, concentration of solute, concentration of PVA, transmembrane pressure and composition of blend membranes were investigated. It was found that percentage rejection improved at a pH 6 and a macroligand concentration of 2 wt.%. The transmembrane pressure and concentration of solute also have an effect on the separation and product rate efficiencies of the blend membranes.

Keywords: Acetate, Binding, Cellulose, Cellulose Acetate, Chromium, Composition, Concentration, Concentrations, Constants, Flux, Heavy Metal, Heavy Metal Ion, Hydrolysis, Inversion, Ion, Ketone, Macroligand, Membranes, Metal, Metal-Ions, Metals, Permeate Flux, pH, Polymer, Precipitation, Pressure, PVA, Rejection, Separation, Streams, Tanning Agent, Toxic, Toxic Metals, Ultrafiltration, Waste-Water

? Aşçı, Y., Nurbaş, M. and Sağ Açıkel, Y. (2007), Sorption of Cd(II) onto kaolin as a soil component and desorption of Cd(II) from kaolin using rhamnolipid biosurfactant. Journal of Hazardous Materials, 139 (1), 50-56.

Full Text: 2007\J Haz Mat139, 50.pdf

Abstract: In this study, a microbial surfactant, rhamnolipid, was investigated for its potential to enhance recovery of Cd(II) from kaolin, a representative soil component. The study was divided into two parts. In the first part, the sorption of Cd(II) ions to kaolin was investigated as a function of pH and initial Cd(II) ion concentration. Kaolin was also shown to be a good sorbent for treatment of Cd(II) ions from waste waters. The equilibrium sorption capacity for Cd(II) ions was measured and extrapolated using the Langmuir, Freundlich, Redlich-Peterson, and Koble-Corrigan sorption models. The best correlation between experimental and model predicted equilibrium uptake was obtained using the Kolbe-Corrigan sorption model. The values of parameters of the Koble-Corrigan model were determined as A= 11.13 (mmol1-bkg^-1 L_b); B= 0.39 (L_b mmol^-b); b= 0.48. In the second part, the desorption of Cd(II) from kaolin was investigated as a function of pH, rhamnolipid concentration, and the amount of sorbed Cd(II) by kaolin. The highest Cd(II) desorption efficiency by rhamnolipid biosurfactant from kaolin was obtained at pH 6.8, at an initial Cd(II) ion concentration of 0.87 mM (4.42 mmol Cd(II)/kg kaolin) and at a rhamnolipid concentration of 80 mM and found to be 71.9 % of the sorbed Cd(II).

Keywords: Adsorption, Biosorption, Biosurfactant, Cadmium, Cadmium, Capacity, Cd(II), Cd(II) Ions, Concentration, Correlation, Desorption, Efficiency, Equilibrium, Freundlich, Heavy-Metals, Ion, Kaolin, Langmuir, Metal-Contaminated Soils, Microbial, Microorganisms, Model, Models, Parameters, pH, Recovery, Removal, Rhamnolipid, Soil, Sorbed, Sorption, Sorption Capacity, Surfactant, Surfactant-Enhanced Remediation, Treatment, Uptake, Waste, Waters

? Iqbal, M.J. and Ashiq, M.N. (2007), Adsorption of dyes from aqueous solutions on activated charcoal. Journal of Hazardous Materials, 139 (1), 57-66.

Full Text: 2007\J Haz Mat139, 57.pdf

Abstract: Adsorption of industrially important dyes namely bromophenol blue, alizarine red-S, methyl blue, methylene blue, eriochrome black-T, malachite green, phenol red and methyl violet from aqueous media on activated charcoal has been investigated. The effect of shaking time, pH and temperature on the adsorption behaviour of these dyes has been studied. It was noted that adsorption of all the dyes on activated charcoal decrease with an increase in the pH and the temperature. The adsorption isotherms at different temperatures were found to be of L-type. Adsorption data was fitted to Freundlich, B.E.T and Langmuir isotherms and various adsorption parameters have been calculated. The thermodynamic parameters such as ∆G, ∆H and ∆S were calculated from the slopes and intercepts of the linear variation of lnK against 1/T, where K is the adsorption coefficient obtained from Langmuir equations was used. The calculated values for the heat of adsorption and the free energy indicate that adsorption process is favored at low temperatures. All the dyes are found to be chemisorbed on activated charcoal.

Keywords: Activated Charcoal, Adsorbents, Adsorption, Adsorption Isotherm, Adsorption Isotherms, Aqueous Solutions, Basic-Dyes, Behaviour, Bentonite, Bet, Data, Dyes, Energy, Fly-Ash, Freundlich, Heat of Adsorption, Isotherms, Kinetics, Langmuir, Langmuir Equation, Langmuir Isotherms, Malachite Green, Media, Methyl Violet, Methylene Blue, Methylene-Blue, Perlite, pH, Phenol, Removal, Rights, Silica, Solutions, Temperature, Thermodynamic, Thermodynamic Parameters, Thermodynamics, Thermodynamics of Adsorption

? Khazali, O., Abu-El-Halawa, R. and Al-Sou’od, K. (2007), Removal of copper(II) from aqueous solution by Jordanian pottery materials. Journal of Hazardous Materials, 139 (1), 67-71.

Full Text: 2007\J Haz Mat139, 67.pdf

Abstract: The aim of this work was to assess the possibility of removing some heavy metals from water by a low-cost adsorbent, like Jordanian raw pottery. Five types of raw and modified pottery materials have been investigated. The effects of initial metal concentration, agitation time, pH and temperature on the removal of Cu(II) were studied. A pseudo-first order was used to test the adsorption kinetics. In order to investigate the sorption isotherm, two equilibrium models, the Freundlich and Langmuir isotherms, were analyzed. The effect of solution pH on the adsorption onto pottery was studied in the pH range 1–5. The adsorption was exothermic at ambient temperature and the computation of the parameters, ΔH, ΔS and ΔG, indicated the interactions to be thermodynamically favorable.

Keywords: Activated Carbon, Adsorbent, Adsorption, Adsorption Kinetics, Ambient, Ambient Temperature, Ash, Concentration, Copper(II), Effects, Equilibrium, Freundlich, Heavy Metals, Heavy-Metals, Interactions, Isotherm, Isotherms, Kinetics, Langmuir, Lead, Materials, Metal, Metal Adsorption, Metals, Models, Modified, Parameters, Peat, pH, Pottery, Pseudo-First Order, Range, Recovery, Removal, Solution pH, Sorption, Sorption Isotherm, Sorption Kinetics, Temperature, Test, Waste-Water, Water

? Bhatnagar, A. (2007), Removal of bromophenols from water using industrial wastes as low cost adsorbents. Journal of Hazardous Materials, 139 (1), 93-102.

Full Text: 2007\J Haz Mat139, 93.pdf

Abstract: A comparative study of the adsorbents prepared from several industrial wastes for the removal of 2-bromophenol, 4-bromophenol and 2,4-dibromophenol has been carried out. The results show that maximum adsorption on carbonaceous adsorbent prepared from fertilizer industry waste has been found to be 40.7, 170.4 and 190.2 mg g^-1 for 4-bromophenol 2-bromophenol and 2,4-dibromophenol, respectively. As compared to carbonaceous adsorbent, the other three adsorbents (viz., blast furnace sludge, dust, and slag) adsorb bromophenols to a much smaller extent. This has been attributed to the carbonaceous adsorbent having a larger porosity and consequently higher surface area. The adsorption of bromophenols on this adsorbent has been studied as a function of contact time, concentration and temperature. The adsorption has been found to be endothermic, and the data conform to the Langmuir equation. The further analysis of data indicates that adsorption is a first order process. A comparative study of adsorption results with those obtained on standard activated charcoal sample shows that prepared carbonaceous adsorbent is about 45% as efficient as standard activated charcoal in removing bromophenols. To test the practical utility of this adsorbent, column operations were also carried out. The results were found satisfactory in removing bromophenols by column operations. Therefore, the present investigations recommend the use of carbon slurry waste as inexpensive adsorbent for small scale industries of developing / poor countries where disposal of solid waste of various industries and proper treatment of polluted wastewater is a serious problem.

Keywords: Activated Charcoal, Adsorbent, Adsorbents, Adsorption, Agricultural Waste, Analysis, Aqueous-Solutions, Batch and Column Studies, Blast Furnace, Bromophenols, Carbon, Carbonaceous, Charcoal, Concentration, Copper(II), Cost, Disposal, Dust, Equilibrium, Fly-Ash, Industrial, Industrial Wastes, Investigations, Langmuir, Langmuir Equation, Lead(II), Phenols, Pollutants, Porosity, Removal, Scale, Slag, Sludge, Slurry, Solid Waste, Sorption, Standard, Surface, Surface Area, Temperature, Test, Treatment, Utility, Waste, Wastes, Wastewater, Water

? Memon, S.Q., Memon, N., Shah, S.W., Khuhawar, M.Y. and Bhanger M.I. (2007), Sawdust – A green and economical sorbent for the removal of cadmium(II) ions. Journal of Hazardous Materials,