Personal Research Database

Full Text: 2005\J Haz Mat124, 181.pdf

Abstract: This is a study about making use of two residual materials such as sludges from a sewage treatment plant and discarded lyres to generate activated carbons and later optimize the production process. H₂SO₄ and ZnCl₂ were used as chemical activating agents. Liquid-phase adsorption tests were made using the produced carbons to retain methylene blue and iodine. The best precursor was sludge activated with ZnCl₂. After optimization studies, the best production methodology involved a 1:1 ratio of sludge and ZnCl₂, a heating rate of 5C/min up to 650C and a residence time of 5 min. The resulting materials adsorbed up to 139.4 mg/g of methylene blue and 1358.5 mg/g of iodine. Nevertheless these carbons may leach Zn while using. To avoid this two treatments were carried out: one consisting of a coating with a polymer and another involving an intensive washing, which was seen to be more efficient. (c) 2005 Elsevier B.V. All rights reserved.

Keywords: Activated Carbons, Liquid-Phase Adsorption, Sewage Sludges, Tyres, Aqueous-Solutions, Chemical Activation, Adsorption, Dyes, Removal, Waste, Equilibrium, Adsorbents, Sorption

? Karthikeyan, T., Rajgopal, S. and Miranda, L.R. (2005), Chromium(VI) adsorption from aqueous solution by Hevea Brasilinesis sawdust activated carbon. Journal of Hazardous Materials, 124 (1-3), 192-199.

Full Text: 2005\J Haz Mat124, 192.pdf

Abstract: Adsorption capacity of Cr(VI) onto Hevea Brasilinesis (Rubber wood) sawdust activated carbon was investigated in a batch system by considering the effects of various parameters like contact time, initial concentration, pH and temperature. Cr(VI) removal is pH dependent and found to be maximum at pH 2.0. Increases in adsorptioncapacity with increase in temperature indicate that the adsorption reaction is endothermic. Based on this study, the thermodynamic parameters like standard Gibb’s free energy (ΔG°), standard enthalpy (ΔH°) and standard entropy (ΔS°) were evaluated. Adsorption kinetics of Cr(VI) ions onto rubber wood sawdust activated carbon were analyzed by pseudo first-order and pseudo second-order models. Pseudo second-order model was found to explain the kinetics of Cr(VI) adsorption most effectively. Intraparticle diffusion studies at different temperatures show that the mechanism of adsorption is mainly dependent on diffusion. The rate of intraparticle diffusion, film diffusion coefficient and pore diffusion coefficient at various temperatures were evaluated. The Langmuir, Freundlich and Temkin isotherm were used to describe the adsorption equilibrium studies of rubber wood sawdust activated carbon at different temperatures. Langmuir isotherm shows better fit than Freundlich and Temkin isotherm in the temperature range studied. The result shows that the rubber wood sawdust activated carbon can be efficiently used for the treatment of wastewaters containing chromium as a low cost alternative compared to commercial activated carbon and other adsorbents reported.

Keywords: Activated Carbon, Adsorbents, Adsorption, Adsorption Capacity, Adsorption Equilibrium, Adsorption Kinetics, Alternative, Aqueous Solution, Batch, Batch System, Capacity, Carbon, Chromium, Chromium(VI), Concentration, Contact, Copper, Cost, Cr(VI), Cr(VI) Adsorption, Cr(VI) Removal, Diffusion, Diffusion Coefficient, Effects, Effluents, Endothermic, Energy, Enthalpy, Entropy, Equilibrium, Equilibrium Studies, Film, Film Diffusion, First Order, Freundlich, Hazelnut Shell, Hexavalent Chromium, Intraparticle, Intraparticle Diffusion, Ions, Isotherm, Kinetics, Kinetics, Langmuir, Langmuir Isotherm, Low Cost, Mechanism, Mechanism of Adsorption, Model, Models, pH, pH-Dependent, Pore Diffusion, Pseudo, Pseudo First Order, Pseudo First-Order, Pseudo Second Order, Pseudo Second-Order, Pseudo-First-Order, Pseudo-Second-Order, Removal, Rights, Rubber Wood Sawdust, Rubber-Wood, Rubberwood, Sawdust, Second Order, Second-Order, Second-Order Model, Solution, Sorption, Standard, Temkin Isotherm, Temperature, Thermodynamic, Thermodynamic Parameters, Time, Treatment, Wastewaters, Wood

? Özcan, A., Özcan, A.S., Tunali, S., Akar, T. and Kiran, I. (2005), Determination of the equilibrium, kinetic and thermodynamic parameters of adsorption of copper(II) ions onto seeds of Capsicum annuum. Journal of Hazardous Materials, 124 (1-3), 200-208.

Full Text: 2005\J Haz Mat124, 200.pdf

Abstract: Adsorption of copper ions onto Capsicum annuum (red pepper) seeds was investigated with the variation in the parameters of pH, contact time, adsorbent and copper(II) concentrations and temperature. The nature of the possible adsorbent and metal ion interactions was examined by the FTIR technique. The copper(II) adsorption equilibrium was attained within 60 min. Adsorption of copper(II) ions onto C. annuum seeds followed by the Langmuir, Freundlich and Dubinin–Radushkevich (D–R) isotherm models. Maximum adsorption capacity (q_max) of copper(II) ions onto red pepper seeds was 4.47×10⁻⁴ mol g⁻¹ at 50°C. Three kinetic models including the pseudo-first-order, pseudo-second-order and intraparticle diffusion equations were selected to follow the adsorption process. Kinetic parameters such as rate constants, equilibrium adsorption capacities and related correlation coefficients, for each kinetic model were calculated and discussed. It was indicated that the adsorption of copper(II) ions onto C. annuum seeds could be described by the pseudo-second-order kinetic model and also followed the intraparticle diffusion model up to 60 min, but diffusion is not only the rate controlling step. Thermodynamics parameters such as the change of free energy, enthalpy and entropy were also evaluated for the adsorption of copper(II) ions onto C. annuum seeds.

Keywords: Adsorbent, Adsorption, Adsorption Capacities, Adsorption Capacity, Adsorption Equilibrium, Capacity, Copper, Copper(II), Correlation, Diffusion, Diffusion Model, Energy, Enthalpy, Entropy, Equilibrium, Freundlich, FTIR, Intraparticle Diffusion, Intraparticle Diffusion Model, Isotherm, Kinetic, Kinetic Model, Kinetic Models, Kinetic Parameters, Kinetics, Langmuir, Metal, Model, Models, pH, Pseudo First Order, Pseudo Second Order, Pseudo-First-Order, Pseudo-Second-Order, Pseudo-Second-Order Kinetic Model, Rate Constants, Temperature, Thermodynamic, Thermodynamic Parameters, Thermodynamics

? Wang, W.M. and Fthenakis, V. (2005), Kinetics study on separation of cadmium from tellurium in acidic solution media using ion-exchange resins. Journal of Hazardous Materials, 125 (1-3), 80-88.

Full Text: 2005\J Haz Mat125, 80.pdf

Abstract: The feasibility of using ion-exchange resins to separate cadmium from tellurium in acidic solutions of the two metals was investigated. We studied the competitive adsorption of cadmium and tellurium in such resins under varying acid strengths and contact time. We found that low sulfuric acid strength (i.e., 0.5 M) was most effective in removing cadmium from solutions. Different ion-exchange resins were tested for their affinity for cadmium and tellurium ions. In the selected systems, the ion-exchange rate of cadmium was rapid in the first 20 min, and reached equilibrium within 2 h. The Lagergren first-order model described the kinetic data with high coefficient of determination and correlation values. At room temperatures the ion-exchange for cadmium onto the resin followed the Freundlich isotherm model. The maximum removal of cadmium obtained from batch studies using resin A was 91%. Column studies with the same resin showed a removal of cadmium of 99.99% or higher.

Keywords: Cadmium, Tellurium, Waste Management, Ion-Exchange, Recycling, Photovoltaics

? Li, F., Wang, Y.F., Yang, Q.Z., Evans, D.G., Forano, C. and Duan, X. (2005), Study on adsorption of glyphosate (N-phosphonomethyl glycine) pesticide on MgAl-layered double hydroxides in aqueous solution. Journal of Hazardous Materials, 125 (1-3), 89-95.

Full Text: 2005\J Haz Mat125, 89.pdf

Abstract: MgAl-layered double hydroxides with different interlayer anions (nitrate, carbonate and chloride) were evaluated for their abilities to adsorb the organic pesticide glyphosate (N-phosphonomethyl glycine, Gly). The adsorption isotherms of Gly on layered double hydroxides (LDHs) nitrate were described by the Langmuir equation at lower equilibrium concentration of Gly (C_e < 1.0 mmol/L), and the Gly adsorption capacity on LDHs increased with the layer charge density, i.e. the structural Al³⁺/Mg²⁺ ratio. Gly adsorption on LDHs nitrate generally occurred through two processes, external surface adsorption and interlayer anion exchange. The adsorption amount on LDHs at C_e = 1.0 mmol/L decreased in the order of interlayer anions: Cl⁻ > NO₃⁻ > CO₃²⁻.

Keywords: Layered Double Hydroxides, Glyphosate (N-Phosphonomethyl Glycine), Water Treatment, Pesticides, Environmental

? Sharma, A. and Bhattacharyya, K.G. (2005), Azadirachta indica (Neem) leaf powder as a biosorbent for removal of Cd(II) from aqueous medium. Journal of Hazardous Materials, 125 (1-3), 102-112.

Full Text: 2005\J Haz Mat125, 102.pdf

Abstract: A biosorbent, Neem leaf powder (NLP), was prepared from the mature leaves of the Azadirachta indica (Neem) tree by initial cleaning, drying, grinding, washing to remove pigments and redrying. The powder was characterized with respect to specific surface area (21.45 m² g⁻¹), surface topography and surface functional groups and the material was used as an adsorbent in a batch process to remove Cd(II) from aqueous medium under conditions of different concentrations, NLP loadings, pH, agitation time and temperature. Adsorption increased from 8.8% at pH 4.0 to 70.0% at pH 7.0 and 93.6% at pH 9.5, the higher values in alkaline medium being due to removal by precipitation. The adsorption was very fast initially and maximum adsorption was observed within 300 min of agitation. The kinetics of the interactions was tested with pseudo first order Lagergren equation (mean k₁ = 1.2×10⁻² min⁻¹), simple second order kinetics (mean k₂ = 1.34×10⁻³ g mg⁻¹ min⁻¹), Elovich equation, liquid film diffusion model (mean k = 1.39×10⁻² min⁻¹) and intra-particle diffusion mechanism. The adsorption data gave good fits with Langmuir and Freundlich isotherms and yielded Langmuir monolayer capacity of 158 mg g⁻¹ for the NLP and Freundlich adsorption capacity of 18.7 L g⁻¹. A 2.0 g of NLP could remove 86% of Cd(II) at 293 K from a solution containing 158.8 mg Cd(II) per litre. The mean values of the thermodynamic parameters, ΔH, ΔS and ΔG, at 293 K were −73.7 kJ mol⁻¹, −0.24 J mol⁻¹ K⁻¹ and −3.63 kJ mol⁻¹, respectively, showing the adsorption process to be thermodynamically favourable. The results have established good potentiality for the Neem leaf powder to be used as a biosorbent for Cd(II).

Keywords: Adsorbent, Adsorption, Adsorption, Adsorption Capacity, Adsorption Process, Agitation, Agitation Time, Alkaline, Aqueous Medium, Azadirachta Indica, Batch, Biosorbent, Bone Char, Breakthrough Curve, Cadmium, Capacity, Cd(II), Cleaning, Column Study, Concentrations, Copper, Desorption Study, Diffusion, Diffusion Model, Drying, Elovich, Elovich Equation, Equilibrium, Film, Film Diffusion, First Order, Freundlich, Freundlich Isotherms, Functional, Functional Groups, G, Grinding, Groups, Heavy-Metals, Interactions, Intra Particle Diffusion, Intra-Particle Diffusion, Intraparticle, Intraparticle Diffusion, Ions, Isotherms, Kinetics, Kinetics, Lagergren, Lagergren Equation, Langmuir, Langmuir and Freundlich Isotherms, Langmuir Monolayer, Leaf, Leaves, Liquid Film Diffusion, Mechanism, Model, Monolayer, Monolayer Capacity, Neem Leaf Powder, Order, Parameters, pH, Pigments, Powder, Precipitation, Process, Pseudo-First-Order, Removal, Second Order, Second Order Kinetics, Sorption, Specific Surface, Specific Surface Area, Surface, Surface Area, Surface Functional Groups, Temperature, Thermodynamic, Thermodynamic Parameters, Thermodynamics, Time, Topography, Tree, Washing, Waste-Water

? Zainal, Z., Hui, L.K., Hussein, M.Z., Taufiq-Yap, Y.H., Abdullah, A.H. and Ramli, I. (2005), Removal of dyes using immobilized titanium dioxide illuminated by fluorescent lamps. Journal of Hazardous Materials, 125 (1-3), 113-120.

Full Text: 2005\J Haz Mat125, 113.pdf

Abstract: The photodegradation of various dyes in aqueous solution was studied. Experiments were carried out using glass coated titanium dioxide thin film as photocatalyst. Photodegradation processes of methylene blue (MB), methyl orange (MO), indigo carmine (IC), chicago sky blue 6B (CSB), and mixed dye (MD, mixture of the four mentioned single dye) were reported. As each photodegradation system is pH dependent, the photodegradation experiment was carried out in each dye photodegradation reactive pH range at ≈28 °C. The dyes removal efficiency was studied and compared using UV–vis spectrophotometer analysis. The total removal of each dye was: methylene blue (90.3%), methyl orange (98.5%), indigo carmine (92.4%), chicago sky blue 6B (60.3%), and mixed dyes (70.1%), respectively. The characteristic of the photocatalyst was investigated using X-ray diffractometer (XRD). The amount of each dye intermediate produced in the photodegradation process was also determined with the help of total organic carbon (TOC) analysis.

Keywords: Photodegradation, Dyes, Immobilized Photocatalyst, Visible Light, Intermediates

? Padmesh, T.V.N., Vijayaraghavan, K., Sekaran, G. and Velan, M. (2005), Batch and column studies on biosorption of acid dyes on fresh water macro alga Azolla filiculoides. Journal of Hazardous Materials, 125 (1-3), 121-129.

Full Text: 2005\J Haz Mat125, 121.pdf

Abstract: The biosorption of Acid red 88 (AR88), Acid green 3 (AG3) and Acid orange 7 (AO7) by deactivated fresh water macro alga Azolla filiculoides was investigated in batch mode. Langmuir and Freundlich adsorption models were used for the mathematical description of the batch biosorption equilibrium data and model constants were evaluated. The adsorption capacity was pH dependent with a maximum value of 109.0 mg/g at pH 7 for AR88, 133.5 mg/g at pH 3 for AG3 and 109.6 mg/g at pH 3 for AO7, respectively, was obtained. The pseudo first and second order kinetic models were also applied to the experimental kinetic data and high correlation coefficients favor pseudo second order model for the present systems. The ability of A. filiculoides to biosorb AG3 in packed column was also investigated. The column experiments were conducted to study the effect of important design parameters such as initial dye concentration (50–100 mg/L), bed height (15–25 cm) and flow rate (5–15 mL/min) to the well-adsorbed dye. At optimum bed height (25 cm), flow rate (5 mL/min) and initial dye concentration (100 mg/L), A. filiculoides exhibited 28.1 mg/g for AG3. The Bed Depth Service Time model and the Thomas model were used to analyze the experimental data and the model parameters were evaluated.

Keywords: Acid Dyes, Acid Green 3, Acid Orange 7, Acid Red 88, Adsorption, Adsorption Capacity, Azolla Filiculoides, Batch, Batch and Column Studies, Batch Mode, Biosorption, Capacity, Column, Column Experiments, Column Studies, Concentration, Correlation, Data, Design, Dye, Dyes, Equilibrium, Experimental, Experiments, First, Flow, Freundlich, Kinetic, Kinetic Models, Langmuir, Mode, Model, Models, Packed Column, pH, pH-Dependent, Pseudo Second Order, Pseudo-Second-Order, Second Order, Second-Order, Systems, Thomas Model, Value, Water

? Shukla, S.R. and Pai, R.S. (2005), Comparison of Pb(II) uptake by coir and dye loaded coir fibres in a fixed bed column. Journal of Hazardous Materials, 125 (1-3), 147-153.

Full Text: 2005\J Haz Mat125, 147.pdf

Abstract: The possibility of adsorbing Pb(II) from solution using coir, a cheap lignocellulosic fibre, was assessed in a fixed bed column. The coir fibres were also chemically modified by covalent loading of a reactive dye, C.I. Reactive Orange 13, and used as adsorbent. Column adsorption studies were carried out at different initial Pb(II) concentrations and it was observed that the breakthrough time decreased with increase in the initial Pb(II) concentration. The column packed with dye loaded coir fibres was operated for longer duration than the one packed with unmodified coir fibres. The total Pb(II) adsorbed was also higher in a column packed with dye loaded coir fibres. The desorption level in the fixed bed column packed with coir fibres was of the order of 85%, whereas the one packed with dye loaded coir fibres was more than 90%. Both the columns were regenerated and used upto five cycles.

Keywords: Adsorption, Coir, Dye, Fixed Bed, Lignocellulosic Fibre

? Dursun, G., Çiçek, H. and Dursun, A.Y. (2005), Adsorption of phenol from aqueous solution by using carbonised beet pulp. Journal of Hazardous Materials, 125 (1-3), 175-182.

Full Text: 2005\J Haz Mat125, 175.pdf

Abstract: The beet pulp, a major low value by-product in sugar industry was used to prepare carbon for phenol adsorption. It was produced by carbonisation in N₂ atmosphere at 600 °C for 1.5 h. The surface area of beet pulp carbon was measured as 47.5 m² g⁻¹ by using BET method.

The adsorption studies of phenol from aqueous solution on beet pulp carbon (BPC) have been studied in the range of 25–500 mg dm⁻³ initial phenol concentrations and at the temperatures of 25, 40 and 60 °C. The maximum phenol adsorption capacity was obtained as 89.5 mg g⁻¹at the temperature of 60 °C at pH = 6.0. The Freundlich and Langmuir adsorption models were used for the mathematical description of the adsorption equilibrium and it was reported that experimental data fitted very well to Freundlich model, although they could be modelled by the Langmuir equation. Batch adsorption models, based on the assumption of the pseudo-first order and pseudo-second order mechanism, were applied to examine the kinetics of the adsorption. The results showed that kinetic data were followed more closely the pseudo-second order model than the pseudo-first order. The thermodynamic parameters such as, equilibrium constant (K), Gibbs free energy changes (ΔG°), standard enthalpy change (ΔH°) and standard entropy change (ΔS°) had been determined. The results show that adsorption of phenol on BPC is an endothermic and spontaneous in nature.

Keywords: Adsorption, Adsorption Capacity, Adsorption Equilibrium, Aqueous Solution, Atmosphere, Batch Adsorption, Beet Pulp Carbon (BPC), BET, Capacity, Carbon, Carbonisation, Changes, Data, Endothermic, Energy, Enthalpy, Entropy, Equilibrium, Experimental, Freundlich, Freundlich Model, Gibbs Free Energy, Kinetic, Kinetics, Langmuir, Langmuir Equation, Mechanism, Model, Models, Phenol, Pseudo First Order, Pseudo Second Order, Pseudo-First Order, Pseudo-First Order and Pseudo-Second Order, Pseudo-First-Order, Pseudo-Second Order, Pseudo-Second Order Mechanism, Pseudo-Second Order Model, Pseudo-Second-Order, Solution, Standard, Sugar Industry, Surface, Surface Area, Temperature, Thermodynamic, Thermodynamic Parameters, Value

? Kaya, A. and Ören, A.H. (2005), Adsorption of zinc from aqueous solutions to bentonite. Journal of Hazardous Materials, 125 (1-3), 183-189.

Full Text: 2005\J Haz Mat125, 183.pdf

Abstract: The adsorptive properties of natural and Na-enriched bentonite in zinc rich aqueous environment have been studied. The results show that adsorption behavior of both bentonites was strongly depending on the pH. At low pH values, the mechanisms that govern the adsorption behavior of bentonites are dissolution of crystal structure and competition of the metal ions with the H⁺. Between pH 4 and 7, the basic mechanism is an ion exchange process. The alkaline and alkaline earth metals located in the exchangeable sites of bentonites are replaced with Zn²⁺ cations present in the aqueous solution. At higher pH values (i.e. pH 8), formation of zinc hydroxyl species may result either participation to the adsorption or precipitation onto the bentonites. Therefore, a rapid increase in the equilibrium removal of zinc was obtained above pH 7. Increase in the initial metal ion concentration led to the increase in equilibrium adsorption to a certain degree; then, a plateau was obtained at higher concentrations. The rate of zinc removal depends also on the solid concentration of the suspension. Reducing the slurry concentration allows particles to get in the more dispersed form, resulting higher available sorption sites for zinc. As a result, the adsorption performance of Na-enriched bentonite is better than the natural bentonite in all physical and chemical changes. The data were fitted both Langmuir and Freundlich isotherms.

Keywords: Zinc, Bentonite, Ion Exchange, Heavy Metal Removal, Adsorption

? Pradhan, S., Shukla, S.S. and Dorris, K.L. (2005), Removal of nickel from aqueous solutions using crab shells. Journal of Hazardous Materials, 125 (1-3), 201-204.

Full Text: 2005\J Haz Mat125, 201.pdf

Abstract: Partially converted crab shell waste, which contains chitosan, was used to remove nickel from water. The chelating ability of chitosan makes it an excellent adsorbent for removing pollutants. Advantages of chitosan in crab shells include availability, low cost, and high biocompatibility. The metal uptake by partially converted crab shell waste was successful and rapid. The sorption occurred primarily within 5 min. The sorption mechanism appears to be quite complicated and cannot be adequately described by either the Langmuir or Freundlich theories. Various anions, including chloride, bromide, fluoride, acetate, sulfate, nitrate, and phosphate, were found to have a very small effect on the capacity of the crab shells for uptake of nickel. The effect of pH was also found not to be prominent.

Keywords: Chitosan, Crab Shell, Nickel, Adsorption, Heavy Metal

? Goel, J., Kadirvelu, K., Rajagopal, C. and Garg, V.K. (2005), Removal of Lead(II) by adsorption using treated granular activated carbon: Batch and column studies. Journal of Hazardous Materials, 125 (1-3), 211-220.

Full Text: 2005\J Haz Mat125, 211.pdf

Abstract: In the present study, a deeper understanding of adsorption behavior of Pb(II) from aqueous systems onto activated carbon and treated activated carbon has been attempted via static and column mode studies under various conditions. It probes mainly two adsorbents that is, activated carbon (AC) and modified activated carbon (AC–S). Characterization of both the adsorbents was one of the key focal areas of the present study. This has shown a clear change or demarcation in the various physical and chemical properties of the modified adsorbent from its precursor activated carbon. Both the adsorbents are subjected to static mode adsorption studies and then after a comparison based on isotherm analysis; more efficient adsorbent is screened for column mode adsorption studies. The lead removal increased for sample of treated carbon. The extent of Pb(II) removal was found to be higher in the treated activated carbon. The aim of carrying out the continuous-flow studies was to assess the effect of various process variables, viz., of bed height, hydraulic loading rate and initial feed concentration on breakthrough time and adsorption capacity. This has helped in ascertaining the practical applicability of the adsorbent. Breakthrough curves were plotted for the adsorption of lead on the adsorbent using continuous-flow column operation by varying different operating parameters like hydraulic loading rate (3.0–10.5 m³/(h m²)), bed height (0.3–0.5 m) and feed concentrations (2.0–6.0 mg/l). At the end, an attempt has also been made to model the data generated from column studies using the empirical relationship based on Bohart–Adams model. This model has provided an objective framework to the subjective interpretation of the adsorption system and the model constant obtained here can be used to achieve the ultimate objective of our study that is, up scaling and designing of adsorption process at the pilot plant scale level. AC–S column regeneration using 0.5 and 1.0 M concentration of HNO₃ has been investigated. It has shown a regeneration efficiency of 52.0% with 0.5 M HNO₃.

Keywords: Lead, Adsorption, Treated Activated Carbon (AC–S), Static, Column, Bohart–Adams Model, Regeneration

? Shen, D.S., Liu, X.W. and He, Y.H. (2005), Studies on adsorption, desorption and biodegradation of pentachlorophenol by the anaerobic granular sludge in an upflow anaerobic sludge blanket (UASB) reactor. Journal of Hazardous Materials,