Personal Research Database

Full Text: 2007\J Haz Mat142, 68.pdf

Abstract: Dynamic batch experiments were carried out for the biosorption of basic yellow dye on to the green macro algae Caulerpa scalpelliformis. The factors affecting the sorption process such as the initial concentration of the dye and pH of the solution, the adsorbent dosage and the time of contact were studied. The sorption kinetics followed pseudo-second order kinetic model. The Caulerpa species exhibited a maximum uptake of 27 mg of dye per gram of seaweed. The Boyd’s plot confirmed the external mass transfer as the rate-limiting step. The average effective diffusion coefficient was found to be 2.4710^-4 cm²/s. Sorption equilibrium studies demonstrated that the biosorption followed Freundlich isotherm model, which implies a heterogeneous sorption phenomenon. Various thermodynamic parameters such as enthalpy of sorption ∆H, free energy change ∆G and entropy ∆S were estimated. The negative value of ∆H and negative values of ∆G shows the sorption process is exothermic and spontaneous. The negative value of entropy ∆S shows the decreased randomness at the solid-liquid interface during the sorption of dyes onto green seaweed.

Keywords: Acid-Red-274 AR-274, Adsorbent, Adsorption, Aqueous Solution, Basic Yellow Dye, Batch Experiments, Batch System, Bioaccumulation, Biosorption, Biosorption, Concentration, Decolorization, Diffusion, Diffusion Coefficient, Dosage, Dye, Dyes, Energy, Entropy, Equilibrium, Equilibrium Isotherm, Freundlich, Freundlich Isotherm, Green Seaweed, Heterogeneous, Interface, Isotherm, Kinetic, Kinetic Model, Kinetics, Macroalgae, Mass Transfer, Model, Parameters, Peat, pH, Process, Pseudo-Second Order, Pseudo-Second-Order, Rate Limiting, Reactive Dye, Seaweed, Sorption, Sorption Kinetics, Textile Effluent, Thermodynamic, Thermodynamic Parameters, Transfer, Uptake, Waste-Water

? Chen, J.C. and Tang, C.T. (2007), Preparation and application of granular ZnO/Al₂O₃ Catalyst for the removal of hazardous trichloroethylene. Journal of Hazardous Materials, 142 (1-2), 88-96.

Full Text: 2007\J Haz Mat142, 88.pdf

Abstract: Trichloroethylene (TCE) is a volatile and nerve-toxic liquid, which is widely used in many industries as an organic solvent. Without proper treatment, it will be volatilized into the atmosphere easily and hazardous to the human health and the environment. This study tries to prepare granular ZnO/Al₂O₃ catalyst by a modified oil-drop sol-gel process incorporated the incipient wetness impregnation method and estimates its performance on the catalytic decomposition of TCE. The effects of different preparation and operation conditions are also investigated. Experimental results show that the granular ZnO/Al₂O₃ catalyst has good catalytic performance on TCE decomposition and the conversion of TCE is 98%. ZnO/Al₂O₃(N) catalyst has better performance than ZnO/Al₂O₃(O) at high temperature. 5% active metal concentration and 550C calcination temperature are the better and economic preparation conditions, and the optimum operation temperature and space velocity are 450C and 18000 hr^-1 respectively. The conversions of TCE are similar and all higher than 90% as the oxygen concentration in feed gas is higher than 5%. By Fourier Transform Infrared Spectrography (FTIR) analyses, the major reaction products in the catalytic decomposition of TCE are HCl and CO₂. The Brunauer-Emmett-Teller (BET) surface areas of catalysts are significantly decreased as the calcination temperature is higher than 550C due to the sintering of catalyst materials, as well as the reaction temperature is higher than 150C due to the accumulations of reaction residues on the surfaces of catalysts. These results are also demonstrated by the results of Scanning Electron Micrography (SEM) and Energy Disperse Spectrography (EDS).

Keywords: Catalysis, Trichloroethylene, Zinc Oxide, Sol-Gel, FTIR

? Kundu, S. and Gupta, A.K. (2007), Adsorption characteristics of As(III) from aqueous solution on iron oxide coated cement (IOCC). Journal of Hazardous Materials, 142 (1-2), 97-104.

Full Text: 2007\J Haz Mat142, 97.pdf

Abstract: Contamination of potable ground water with arsenic is a serious health hazard which calls for proper treatment before its use as drinking water. The objective of the present study is to assess the effectiveness of iron oxide coated cement (IOCC) for As(III) adsorption from aqueous solution. Batch studies were conducted to study As(III) adsorption onto IOCC at ambient temperature as a function of adsorbent dose, pH, contact time, initial arsenic concentration and temperature. Kinetics reveal that the uptake of As(III) ion is very rapid and most of fixation occurs within the first 20 min of contact. The pseudo second order rate equation successfully described the adsorption kinetics. Langmuir, Freundlich, Redlich–Peterson (R–P), and Dubinin–Radushkevich (D–R) models were used to describe the adsorption isotherms at different initial As(III) concentrations and at 30 g l^-1 fixed adsorbent dose. The maximum adsorption capacity of IOCC for As(III) determined from the Langmuir isotherm was 0.69 mg g^-1. The mean free energy of adsorption (E) calculated from the D–R isotherm was found to be 2.86 kJ mol^-1 which suggests physisorption. Thermodynamic parameters indicate an exothermic nature of adsorption and a spontaneous and favourable process. The results suggest that IOCC can be suitably used for As(III) removal from aqueous solutions.

Keywords: Activated Alumina, Adsorbent, Adsorption, Adsorption Capacity, Adsorption Isotherms, Adsorption Kinetics, Ambient, Ambient Temperature, Aqueous Solution, Arsenic, Arsenic Removal, As(III), Capacity, Carbon, Cement, Concentration, Concentrations, Drinking Water, Effectiveness, Energy, Equilibrium, Freundlich, Function, Ground-Water, Groundwater, Hazard, Health, Ion, Iron, Iron Oxide Coated Cement, Isotherm, Isotherms, Kinetics, Langmuir, Langmuir Isotherm, Metal-Ions, Models, Parameters, pH, Process, Pseudo-Second Order, Pseudo-Second-Order, Rate Equation, Removal, Sand, Temperature, Thermodynamics, Treatment, Uptake, Water, Zero-Valent Iron

? Gasser, M.S., Morad, G.H.A. and Aly, H.F. (2007), Batch kinetics and thermodynamics of Chromium ions removal from waste solutions using synthetic adsorbents. Journal of Hazardous Materials, 142 (1-2), 118-129.

Full Text: 2007\J Haz Mat142, 118.pdf

Abstract: Mg(OH)₂ was identified as a component in the magnesia cement being adsorbent for Cr(VI). Modified magnesia cement was prepared by the addition of ferric chloride and humic acid. The equilibrium adsorption of Cr(VI) on magnesia cement adsorbents (MF5-1) and (MF5-2) was investigated as a function of contact time, adsorbent weight, solute concentration and temperature. Tests of different isotherms have shown that the adsorption data fit the Langmiur and Freundlich isotherms at 25±1C. The nature of the diffusion process responsible for adsorption of Cr(VI) on (MF5-1) and (MF5-2) adsorbents was discussed. The kinetics and mechanism of diffusion of Cr(VI) into (MF5-1) and (MF5-2) adsorbents from aqueous solution have been studied as a function of Cr(VI) concentrations and reaction temperatures. The adsorption of Cr(VI) on the MF5-1 and MF5-2 adsorbents follows first-order reversible kinetics. The forward and backward constants, k₁ and k₂ have been calculated at different temperatures between 10 and 50C. The heat of activation of the adsorption, ∆H* and ∆S* were calculated for Cr(VI) at 25C. The values of ∆H* were found 18.1 kJmol^-1 and 10.7 kJmol^-1 for MF5-1 and MF5-2 respectively, while entropy change, ∆S*, were found -106.8 Jmol^-1K^-1 and -118.6 Jmol^-1K^-1 for MF5-1 and MF5-2, respectively. The study showed that pore diffusion is the rate determining step in the adsorption of Cr(VI) ions for MF5-1 and MF5-2. MF5-2 was found more efficient for Cr(VI) adsorption than MF5-1. Also Cr(VI) can be adsorbed on MF5-2, whereas Cr(III) cannot. So, the competitive adsorption of multi-metals onto the MF5-2 adsorbent was studied. The studies showed that this adsorbent can be used as an efficient adsorbent material for the removal of Cr(VI) from water and nuclear power plant coolant water.

Keywords: Adsorption, Chromium, Isotherm, Kinetics, Thermodynamics, Mechanism, Wastewater

? Ferrero, F. (2007), Dye removal by low cost adsorbents: Hazelnut shells in comparison with wood sawdust. Journal of Hazardous Materials, 142 (1-2), 144-152.

Full Text: 2007\J Haz Mat142, 144.pdf

Abstract: Batch adsorption of Methylene Blue, up to 1000 mg L^-1, and Acid Blue 25, up to 500 mg L^-1, onto ground hazelnut shells was studied in comparison with sawdust of various species of wood, in order to explore the potential use of this material as low cost adsorbent for dye removal in dyehouse effluents. The adsorption kinetics was investigated according to Lagergren’s model, but the best fit was achieved by a second order equation. The equilibrium data were processed according to Langmuir’s model and higher adsorption capacity values towards both dyes were shown by hazelnut shells than wood sawdust. Moreover, fixed bed adsorption of Methylene Blue was performed on hazelnut shell columns and the breakthrough curves were determined by varying bed depth, flow rate and influent concentration. The data were processed according to Bohart - Adams model and the column performances could be predicted by the bed depth service time (BDST) approach.

Keywords: Acid Dyes, Adsorbent, Adsorbents, Adsorption, Adsorption Capacity, Adsorption Isotherms, Adsorption Kinetics, Aqueous-Solutions, Basic-Dyes, Batch, Capacity, Concentration, Cost, Dye, Dye Adsorption, Dye Removal, Dyes, Effluent, Effluents, Equilibrium, Fixed Bed, Fixed-Bed Systems, Flow, Granular Activated Carbon, Hazelnut Shell, Kinetics, Low, Model, Natural Adsorbents, Peat, Removal, Sawdust, Wood, Wood Sawdust

? Wang, Y.F., Lin, F. and Pang, W.Q. (2007), Ammonium exchange in aqueous solution using Chinese natural clinoptilolite and modified zeolite. Journal of Hazardous Materials, 142 (1-2), 160-164.

Full Text: 2007\J Haz Mat142, 160.pdf

Abstract: In this study, the Chinese natural clinoptilolite (sample 1) was fused with sodium hydroxide prior to hydrothermal reaction, and it was transformed to modified zeolite Na-Y (sample 2). The uptake of ammonium ion from aqueous solutions in the concentration range 50–250 mg NH₄⁺/l on to the two samples was compared and the equilibrium isotherms have been got. The influence of other cations present in water upon the ammonia uptake was also determined. The cations studied were potassium, calcium and magnesium. In all cases the anionic counterion present was chloride. The results showed that sample 2 exhibited much higher uptake capacity compared with sample 1. At the initial concentration of 250 mg NH₄⁺/l, the ammonium ion uptake value of sample 2 was 19.29 mg NH₄⁺ g^-1 adsorbent, while sample 1 was only 10.49 mg NH₄⁺ g^-1 adsorbent. For the natural clinoptilolite, the effect of the metal ions suggested an order of preference K⁺ > Ca²⁺ > Mg²⁺. These contrasted with the modified zeolite, where the order appeared to be Mg²⁺ > Ca²⁺ > K⁺.

Keywords: Clinoptilolite, Zeolite Na-Y, Ion Exchange, Ammonium Uptake

? Oubagaranadin, J.U.K., Sathyamurthy, N. and Murthy, Z.V.P. (2007), Evaluation of Fuller’s earth for the adsorption of mercury from aqueous solutions: A comparative study with activated carbon. Journal of Hazardous Materials, 142 (1-2), 165-174.

Full Text: 2007\J Haz Mat142, 165.pdf

Abstract: Fuller’s earth (FE) has been used as an adsorbent in this work to remove mercury from aqueous solutions. For the purpose of comparison, simultaneous experiments using activated carbon (AC) have also been done. The aim of the work is to test how best FE can be used as an adsorbent for mercury. Equilibrium isotherms, such as Freundlich, Langmuir, Dubinin–Redushkevich, Temkin, Harkins–Jura, Halsey and Henderson have been tested. Kinetic studies based on Lagergren first-order, pseudo-second-order rate expressions and intra-particle diffusion studies have been done. The batch experiments were conducted at room temperature (30 °C) and at the normal pH (6.7±0.2) of the solution. It has been observed that Hg(II) removal rate is better for FE than AC, due to large dosage requirement, whereas the adsorption capacity of AC is found to be much better than FE. Hence, although FE can be used as an adsorbent, a high dosage is required, when compared to AC. Hybrid fractional error function analysis shows that the best-fit for the adsorption equilibrium data is represented by Freundlich isotherm. Kinetic and film diffusion studies show that the adsorption of mercury on FE and AC is both intra-particle diffusion and film diffusion controlled.

Keywords: Activated Carbon, Adsorbent, Adsorption, Adsorption Capacity, Adsorption Equilibrium, Analysis, Batch Experiments, Capacity, Carbon, Comparative Study, Cross-Flow Microfiltration, Diffusion, Divalent Metal-Ions, Dosage, Earth, Electroplating Waste-Water, Equilibrium, Equilibrium Sorption, Fe, Film, Fly-Ash, Freundlich, Freundlich Isotherm, Fuller’S Earth, Function, Fundamental Properties, Heavy-Metals, Hg(II), Industrial-Waste, Intra-Particle Diffusion, Isotherm, Isotherms, Kinetic-Models, Kinetics, Langmuir, Lead Ions, Mercury, pH, Pseudo-Second-Order, Removal, Room Temperature, Temperature, Test, Wastewater Treatment

? Ramos, A.F., Gómez, M.A., Hontoria, E. and González-López, J. (2007), Biological nitrogen and phenol removal from saline industrial wastewater by submerged fixed-film reactor. Journal of Hazardous Materials, 142 (1-2), 175-183.

Full Text: 2007\J Haz Mat142, 175.pdf

Abstract: In this study a biological nitrogen removal process using a submerged fixed-film reactor was applied to treat industrial wastewater with phenol (1 g/l), a high nitrogen concentration (0.4 g N/l) and high salinity (30 g/l). The process consisted of a pre-denitrification system with a down-flow-up-flow biofilter (two columns, each with an effective volume of 21 l) packed with clayey schists from recycled construction material. The efficiency of the system for reducing COD, phenol concentration and total nitrogen was tested under different running conditions such as influent flow (10, 12 and 15 l/d), air loading (6.8 and 13.6 m³/m² h) and effluent recirculation (300%, 400%, and 600%). The system demonstrated a high capacity for reducing COD concentration (95.75±0.72%), independently of running conditions. The aerobic column eliminated most of the phenol in the influent. Nitrogen removal took place mainly in the anoxic column, and was conditioned by the air loading in the aerated column, owing to the dependence of nitrification on the supply of oxygen. However, this process was not able to achieve a nitrogen oxidation superior to 63%, in spite of a sufficient supply of oxygen and the diluting effect of high recirculation (600%) on the phenol concentration in the influent. In spite of the limitations observed in the process of nitrification, results for the removal of total nitrogen were as high as 83%, owing to a combination of different processes for nitrogen removal.

Keywords: Nitrogen Removal, Phenol, Industrial Wastewater Treatment, Pre-Denitrification, Submerged Fixed-Film Reactor

? Álvarez-Ayuso, E., García-Sánchez, A. and Querol, X. (2007), Adsorption of Cr(VI) from synthetic solutions and electroplating wastewaters on amorphous aluminium oxide. Journal of Hazardous Materials, 142 (1-2), 191-198.

Full Text: 2007\J Haz Mat142, 191.pdf

Abstract: The adsorption behaviour of amorphous aluminium oxide was studied with respect to Cr(VI) in order to consider its application to purify electroplating wastewaters. A batch method was employed using Cr(VI) concentrations ranged from 10 to 200 mg/l. The Langmuir model was found to describe the adsorption process well, offering a maximum adsorption capacity of 78.1 mg/g. The effect of ionic strength (0-0.1M KNO₃), pH (3-9) and competitive solutes (molar ratio [Cr(VI)]/[SO₄^2-] = 1 and 100) on the retention process was evaluated. Cr(VI) adsorption on amorphous aluminium oxide appeared to be dependent on ionic strength with a more pronounced effect in acid conditions. Conversely, adsorption was not affected by pH in acid medium, but decreased when pH sifted to alkaline values. The presence of SO₄^2- greatly reduced Cr(VI) removal across the entire pH range when both solutes were present in similar concentrations. Amorphous aluminium oxide also showed a high adsorption capacity when used in the purification of Cr(VI) electroplating wastewaters. The adsorbent doses required to attain more than 90% of Cr(VI) removal varied between 1 and 5 g/l depending on Cr(VI) concentration in wastewaters.

Keywords: Chromium, Adsorption, Aluminium Oxide, Wastewaters, Electroplating

? Hsu, L.C., Wang, S.L., Tzou, Y.M., Lin, C.F. and Chen, J.H. (2007), The removal and recovery of Cr(VI) by Li/Al layered double hydroxide (LDH). Journal of Hazardous Materials, 142 (1-2), 242-249.

Full Text: 2007\J Haz Mat142, 242.pdf

Abstract: Hexavalent Cr has been identified as one of the toxic metals commonly present in industrial effluents. Among the treatment techniques developed for removing Cr(VI) from waste waters, sorption is most commonly applied, due to its simplicity and efficiency. However, few adsorbents can be recycled and reused cost-effectively. In this study, the removal and recovery of Cr(VI) from water using Li/Al LDH was investigated. The removal of Cr(VI) by Li/Al LDH was evaluated in a batch mode. The results demonstrated that Cr(VI) adsorption onto Li/Al LDH occurs by replacing the Cl(-) that originally exists in the interlayer of the adsorbent. The degree of Cr(VI) adsorption observed for Li/Al LDH was relatively high and the process occurred rapidly; however, a portion of adsorbed Cr(VI) was gradually desorbed, due to the Li de-intercalation of Li/Al LDH. Lithium de-intercalation from LVAI LDH with interlayer Cl(-) and interlayer Cr(VI) follows the first order kinetics and has the activation energies of 76.6 and 41.5 kJ mol(-1), respectively. The properties of thermal unstablility and the high adsorption capacity of Li/Al LDH may lead to the development of an innovative technique for the removal of Cr(VI) from Cr(VI)-containing wastewater. That is, LVAI LDH may be used as an effective adsorbent for the adsorption of Cr(VI) in an ambient environment. Following the adsorptive process, the adsorbed Cr(VI) may be released, using heated water to treat the Cr(VI)-containing Li/Al LDH particles. Through this hydrothermal treatment of the used adsorbent, Cr(VI) can be recovered and the solid product (gibbsite) can be recycled for further use. (c) 2006 Elsevier B.V. All rights reserved.

Keywords: Activation, Adsorbent, Adsorption, Adsorption, Adsorption Capacity, Capacity, Chemistry, Chromate, Chromium, Chromium(VI), Cr(VI), Cr(VI) Adsorption, Development, Environment, Exchange, First Order, Hydrotalcite-Like Compounds, Intercalation, Kinetics, LDH, Lead, Li, Al Ldhs, Metals, Ni(II), Physicochemical Properties, Recovery, Removal, Sorption, Treatment, Wastewater, X-Ray-Diffraction

? King, P., Rakesh, N., Beenalahari, S., Kumar, Y.P. and Prasad, V.S.R.K. (2007), Removal of lead from aqueous solution using Syzygium Cumini L.: Equilibrium and kinetic studies. Journal of Hazardous Materials, 142 (1-2), 340-347.

Full Text: 2007\J Haz Mat142, 340.pdf

Abstract: The biosorption of lead ions from aqueous solution by Syzygium Cumini L. was studied in a batch adsorption system as a function of pH, contact time, lead ion concentration, adsorbent concentration and adsorbent size. The biosorption capacities and rates of lead ions onto Syzygium Cumini L. were evaluated. The Langmuir, Freundlich, Redlich-Peterson and Temkin adsorption models were applied to describe the isotherms and isotherm constants. Biosorption isothermal data could be well interpreted by the Langmuir model followed by Temkin model with maximum adsorption capacity of 32.47 mg/g of lead ion on Syzygium Cumini L. leaves biomass. The kinetic experimental data were properly correlated with the second-order kinetic model.

Keywords: Adsorbent, Adsorption, Adsorption, Adsorption Capacity, Adsorption Isotherm, Algal Biomass, Aqueous Solution, Biomass, Biosorption, Cadmium, Capacity, Chemisorption, Concentration, Copper, Desorption, Freundlich, Function, Heavy-Metals, Ion, Ions, Isotherm, Isothermal, Isotherms, Kinetic, Kinetic Model, Kinetic Studies, Langmuir, Lead, Lead Ions, Leaves, Model, Models, pH, Syzygium Cumini l., Waste-Water

? Ponnusami, V., Krithika, V., Madhuram, R. and Srivastava, S.N. (2007), Biosorption of reactive dye using acid-treated rice husk: Factorial design analysis. Journal of Hazardous Materials, 142 (1-2), 397-403.

Full Text: 2007\J Haz Mat142, 397.pdf

Abstract: A factorial experimental design technique was used to investigate the biosorption of reactive red RGB (λmax = 521 nm) from water solution on rice husk treated with nitric acid. Biosorption is favored because of abundance of biomass, low cost, reduced sludge compared to conventional treatment techniques and better decontamination efficiency from highly diluted solutions. Factorial design of experiments is employed to study the effect of four factors pH (2 and 7), temperature (20 and 40), adsorbent dosage (5 and 50 mg/L) and initial concentration of the dye (50 and 250 mg/L) at two levels low and high. The efficiency of color removal was determined after 60 min of treatment. Main effects and interaction effects of the four factors were analyzed using statistical techniques. A regression model was suggested and it was found to fit the experimental data very well. The results were analyzed statistically using the Student’s t-test, analysis of variance, F-test and lack of fit to define most important process variables affecting the percentage dye removal. The most significant variable was thus found to be pH.

Keywords: Rice Husk, Biosorption, Reactive Dye, Red RGB, Color removal, Factorial Design of Experiments

? Cengeloglu, Y., Tor, A., Arslan, G., Ersoz, M. and Gezgin, S. (2007), Removal of boron from aqueous solution by using neutralized red mud. Journal of Hazardous Materials, 142 (1-2), 412-417.

Full Text: 2007\J Haz Mat142, 412.pdf

Abstract: The adsorptive removal of boron from aqueous solution by using the neutralized red mud was studied in batch equilibration technique. The effects of pH, adsorbent dosage, initial boron concentration and contact time on the adsorption were investigated. The experiments demonstrated that boron removal was of a little fluctuation in pH range of 2–7 and it takes 20 min to attain equilibrium. The adsorption data was analyzed using the Langmuir and the Freundlich isotherm models and it was found that the Freundlich isotherm model represented the measured sorption data well.

Keywords: Adsorption, Equilibrium Isotherm, Freundlich Isotherm, Langmuir Isotherm, Boron, Red Mud

? Gupta, V.K., Jain, R. and Varshney, S. (2007), Removal of Reactofix golden yellow 3 RFN from aqueous solution using wheat husk: An agricultural waste. Journal of Hazardous Materials, 142 (1-2), 443-448.

Full Text: 2007\J Haz Mat142, 443.pdf

Abstract: The wheat husk, an agricultural by-product, has been activated and used as an adsorbent for the adsorption of Reactofix golden yellow 3 RFN from aqueous solution. In this work, adsorption of Reactofix golden yellow 3 RFN on wheat husk and charcoal has been studied by using batch studies. The equibrium adsorption level was determined to be a function of the solution pH, adsorbent dosage, dye concentration and contact time. The equilibrium adsorption capacities of wheat husk and charcoal for dye removal were obtained using Freundlich and Langmuir isotherms. Thermodynamic parameters such as the free energies, enthalpies and entropies of adsorption were also evaluated. Adsorption process is considered suitable for removing color, COD from wastewater.

Keywords: Azo dyes, Reactofix Golden Yellow 3 RFN, Adsorption, Wheat Husk

? Sharma, Y.C. and Weng, C.H. (2007), Removal of chromium(VI) from water and wastewater by using riverbed sand: Kinetic and equilibrium studies. Journal of Hazardous Materials,