Personal Research Database

Full Text: 2006\J Haz Mat134, 120.pdf

Abstract: Dead Azolla filiculoides can remove Pb²⁺,Cd²⁺, Ni²⁺ and Zn²⁺ corresponding to second-order kinetic model. The maximum adsorption capacity (Q_max) to remove these metal ions by the alkali and CaCl₂/MgCl₂/NaCl (2:1:1, molar ratio) activated Azolla from 283 to 313 K was 1.431–1.272, 1.173–0.990, 1.365–1.198 and 1.291–0.981 mmol/g dry biomass, respectively. Q_max to remove these heavy metals by the non-activated Azolla at the mentioned temperature range was obtained 1.131–0.977, 1.092–0.921, 1.212–0.931 and 1.103–0.923 mmol/g dry biomass, respectively. In order to remove these metal ions by the activated Azolla, the enthalpy change (ΔH) was −4.403, −4.495, −4.557 and −4.365 kcal/mol and the entropy change (ΔS) was 2.290, 1.268, 1.745 and 1.006 cal/mol K, respectively. While, to remove these metal ions by the non-activated Azolla, ΔH was −3.685, −3.766, −3.967 and −3.731 kcal/mol and ΔS was 2.440, 1.265, 1.036 and 0.933 cal/mol K, respectively. On the other hand, the living Azolla removed these heavy metals corresponding to first-order kinetic model. It was also shown that pH, temperature and photoperiod were effective both on the rate of Azolla growth and the rate of heavy metals uptake during 10 days. It was appeared the use of Ca(NO₃)₂ increased both Azolla growth rate and the rate of heavy metals uptake while the using KNO₃ although increased Azolla growth rate but decreased the rate of heavy metals uptake.

Keywords: Azolla filiculoides, Heavy Metals Uptake, Kinetic and Thermodynamic Study

? Adebowale, K.O., Unuabonah, I.E. and Olu-Owolabi, B.I. (2006), The effect of some operating variables on the adsorption of lead and cadmium ions on kaolinite clay. Journal of Hazardous Materials, 134 (1-3), 130-139.

Full Text: 2006\J Haz Mat134, 130.pdf

Abstract: Modification of kaolinite clay mineral with orthophosphate (p-modified sample) enhanced adsorption of Pb and Cd ions from aqueous solutions of the metal ions. Increasing pH of solutions of metal ions, increasing adsorbent dose and increasing concentration of metal ion, increased the adsorption of metal ions. Adsorption of both metal ions simultaneously on both unmodified and p-modified samples indicates that adsorption of one metal ion is suppressed to some degree by the other.

The presence of electrolyte and their increasing concentration reduced the adsorption capacities of both unmodified and p-modified samples for the metal ions. Ca-electrolytes had more negative effect on the adsorption capacities of the adsorbents than Na-electrolytes. Ca-electrolytes reduced adsorption capacities of the adsorbents for Pb and Cd ions. From Langmuir plots it was observed that these electrolytes increased the binding energy constant of the metal ions unto the adsorbents especially on the p-modified samples.

The rate of adsorption of Pb and Cd ions on p-modified adsorbent were increased and equilibrium of metal ion solution were more quickly reached (8 min for Pb ions and 12 min for Cd ions) with p-modified adsorbent as against 20 min for adsorption of both metal ions on unmodified adsorbent when 200 mg/L of metal ion solutions were used during the kinetic studies.

When adsorption data were fitted against Langmuir, Freundlich, Toth and Langmuir–Freundlich isotherms, satisfactory fits were found with the Freundlich isotherm. However, at low concentration of metal ions, data also showed satisfactory fits to Langmuir isotherm.

Keywords: Adsorption, Kaolinite Clay, p-Modified, Adsorption Capacities

? Catalfamo, P., Arrigo, I., Primerano, P. and Corigliano, F. (2006), Efficiency of a zeolitized pumice waste as a low-cost heavy metals adsorbent. Journal of Hazardous Materials, 134 (1-3), 140-143.

Full Text: 2006\J Haz Mat134, 140.pdf

Abstract: The unextracted residue obtained after a countercurrent two-step extractive process of silica from pumice lapillus, at 100 °C and room pressure, has been found mainly crystallized to the pseudo-cubic form typical of zeolite P. This residue could be active as a low-cost agent for the removal of heavy metals from wastewater.

In this paper the removal capacity of six metallic cations (i.e. Cu²⁺, Ni²⁺, Zn²⁺, Cd²⁺, Pb²⁺ and Cr³⁺) was studied in a stirred batch reactor. Results obtained showed that the removal of metal ions (100–500 mg g⁻¹) from wastewater is achieved in a short time and the concentration lowered under the legal limits.

The adsorption mechanism mainly involves an ionic exchange between sodium ions from the solid phase and heavy metals in solution. However, if wastewater was accompanied by free acidity, it first should be neutralized to pH 4–5 to prevent zeolite destruction.

Keywords: Adsorption, Heavy Metals, Zeolite, Pumice, Low-Cost Adsorbents

? Tsai, W.T. and Lai, C.W. (2006), Adsorption of herbicide paraquat by clay mineral regenerated from spent bleaching earth. Journal of Hazardous Materials, 134 (1-3), 144-148.

Full Text: 2006\J Haz Mat134, 144.pdf

Abstract: The adsorption of herbicide paraquat (as model adsorbate) in aqueous solution onto regenerated clay mineral from bleaching earth waste has been studied in a batch reaction system. The adsorption rate has been investigated under the controlled process parameters including initial pH, salinity and temperature. Based on the high affinity between cationic paraquat and clay mineral, a pseudo-second order model has been developed using experimental data to predict the rate constant of adsorption, and equilibrium adsorption capacity. The results showed that the adsorption process could be satisfactorily described with the reaction model and were reasonably explained by assuming a competitive adsorption mechanism in the ion exchange process. Further, the fitted adsorption capacity at equilibrium decreased with increasing temperature. It implied that the strong interaction might play an important role in the paraquat–clay system. Overall, the results from this study demonstrated that the clay resource regenerated from bleaching earth waste could be used as a low-cost mineral adsorbent for the removal of environmental cationic organic pollutants from the aqueous solution.

Keywords: Adsorbent, Adsorption, Adsorption Capacity, Adsorption Mechanism, Adsorption Rate, Aqueous Solution, Batch, Capacity, Clay, Clay Mineral, Competitive, Competitive Adsorption, Data, Environmental, Equilibrium, Experimental, Herbicide, Interaction, Ion Exchange, Ion-Exchange, Kinetic Modeling, Liquid-Phase Adsorption, Mechanism, Model, Organic, Organic Pollutants, Paraquat, pH, Pollutants, Pseudo Second Order, Pseudo-Second Order, Pseudo-Second Order Model, Pseudo-Second-Order, Rate Constant, Regenerated Bleaching Earth, Removal, Role, Salinity, Solution, Temperature, Waste

? Pehlivan, E. and Altun, T. (2006), The study of various parameters affecting the ion exchange of Cu²⁺, Zn²⁺, Ni²⁺, Cd²⁺, and Pb²⁺ from aqueous solution on Dowex 50W synthetic resin. Journal of Hazardous Materials, 134 (1-3), 149-156.

Full Text: 2006\J Haz Mat134, 149.pdf

Abstract: A gel resin containing sulfonate groups (Dowex 50W) was investigated for its sorption properties towards copper, zinc, nickel, cadmium and lead metal ions. The use of selective ion exchange to recover metals from aqueous solution has been studied. The ion exchange behavior of five metals on Dowex 50W, depending on pH, temperature, and contact time and adsorbate amount was studied. Experimental measurements have been made on the batch sorption of toxic metals from aqueous solutions using cation exchanger Dowex 50W. The maximum recoveries (about 97%) Cu²⁺, Zn²⁺, Ni²⁺, Cd²⁺ and (about 80%) Pb²⁺ were found at pH ranges 8–9. The amount of sorbed metal ion was calculated as 4.1, 4.6, 4.7, 4.8, and 4.7 mequiv./gram dry resin for Pb²⁺, Cu²⁺, Zn²⁺, Cd²⁺, and Ni²⁺, respectively. The precision of the method was examined at under optimum conditions. Selectivity increased in the series: Pb > Cd > Cu > Zn > Ni. It has been observed that, selectivity of the –SO₃H group of the resin increases with atomic number, valance, degree of ionization of the exchanged metals. The equilibrium ion exchange capacity of resin for metal ions was measured and explored by using Freundlich and Langmuir isotherms. Langmuir type sorption isotherm was suitable for equilibrium studies.

Keywords: Sorption, Ion Exchange, Dowex 50W, Metal Sorption, Heavy Metals

? Tsai, W.T., Lai, C.W. and Su, T.Y. (2006), Adsorption of bisphenol-A from aqueous solution onto minerals and carbon adsorbents. Journal of Hazardous Materials, 134 (1-3), 169-175.

Full Text: 2006\J Haz Mat134, 169.pdf

Abstract: The adsorption behaviors of bisphenol-A, which has been listed as one of endocrine disrupting chemicals, from aqueous solution onto four minerals including andesite, diatomaceous earth, titanium dioxide, and activated bleaching earth, and two activated carbons with coconut-based and coal-based virgins were examined in this work. Based on the adsorption results at the specified conditions, the adsorption capacities of activated carbons are significantly larger than those of mineral adsorbents, implying that the former is effective for removal of the highly hydrophobic adsorbate from the aqueous solution because of its high surface area and low surface polarity. The adsorption capacities of bisphenol-A onto these mineral adsorbents with different pore properties are almost similar in magnitude mainly due to the weakly electrostatic interaction between the mineral surface with negative charge and the target adsorbate with hydrophobic nature. Further, a simplified kinetic model, pseudo-second-order, was tested to investigate the adsorption behaviors of bisphenol-A onto the two common activated carbons at different solution conditions. It was found that the adsorption process could be well described with the pseudo-second-order model. The kinetic parameters of the model obtained in the present work are in line with the pore properties of the two adsorbents.

Keywords: Activated Carbon, Activated Carbons, Adsorbents, Adsorption, Adsorption Capacities, Aqueous Solution, Bisphenol-A, Carbon, Charge, Chemicals, Interaction, Kinetic, Kinetic Model, Kinetic Modeling, Kinetic Parameters, Mineral Adsorbent, Minerals, Model, Pseudo Second Order, Pseudo-Second-Order, Pseudo-Second-Order Model, Removal, Solution, Surface, Surface Area, Titanium, Titanium Dioxide, Work

? Gulnaz, O., Kaya, A. and Dincer, S. (2006), The reuse of dried activated sludge for adsorption of reactive dye. Journal of Hazardous Materials, 134 (1-3), 190-196.

Full Text: 2006\J Haz Mat134, 190.pdf

Abstract: Adsorption processes are alternative effective methods for removal of textile dyes from aqueous solutions. The adsorption ability of adsorbent affects by physico-chemical environment for this reason in this paper effect of initial pH, dye concentrations, temperature and dye hydrolyzation were determined in a batch system for removal of reactive dye by dried activated sludge. The Langmuir isotherm model was well described of adsorption reactive dye and maximum monolayer adsorption capacity (at pH 2) of activated sludge was determined as 116, 93 and 71 mg g⁻¹ for 20, 35 and 50 °C, respectively. Initial pH 2, 20 °C and 30 min contact time are suitable for removal of reactive dyes from aqueous solutions. Activated sludge was characterized by FT-IR analysis and results showed that active sludge has different functional groups and functional groups of activated sludge are able to react with dye molecules in aqueous solution. The pseudo first-order, second-order and intraparticle diffusion kinetics were used to describe the kinetic data. The pseudo second-order kinetic model was fit well over the range of contact times and also an intra particle diffusion kinetic model was fit well but in the first 30 min. The dye hydrolyzation was affected adsorption capacity of biomass and adsorption capacity of biomass decreased with dye hydrolyzation from 74 to 38 mg g⁻¹.

Keywords: Activated Sludge, Adsorbent, Adsorption, Adsorption Capacity, Alternative, Analysis, Aqueous Solution, Aqueous Solutions, Batch, Batch System, Biomass, Capacity, Data, Diffusion, Dried Activated Sludge, Dye, Dyes, Environment, First, First Order, FT-IR, FTIR, Functional Groups, Intraparticle Diffusion, Isotherm, Isotherm Model, Kinetic, Kinetic Model, Kinetic Modelling, Kinetics, Langmuir, Langmuir Isotherm, Langmuir Isotherm Model, Methods, Model, Monolayer, Particle Diffusion, pH, Pseudo First Order, Pseudo First-Order, Pseudo Second Order, Pseudo Second-Order, Pseudo-First-Order, Pseudo-Second-Order, Reactive Black 5, Reactive Dye, Reactive Dyes, Removal, Reuse, Second Order, Second-Order, Sludge, Solution, Solutions, Temperature

? Tekin, N., Dinçer, A., Demirbaş, Ö. and Alkan, M. (2006), Adsorption of cationic polyacrylamide onto sepiolite. Journal of Hazardous Materials, 134 (1-3), 211-219.

Full Text: 2006\J Haz Mat134, 211.pdf

Abstract: The adsorption of PAM onto sepiolite from aqueous solutions has been investigated systematically as a function of some parameters such as calcination temperature of sepiolite, pH, ionic strength and temperature. The adsorption of cationic polyacrylamide (PAM) increases with pH from 5.50 to 11.00, temperature from 25 to 55 °C and ionic strength from 0 to 0.1 mol L⁻¹. The sepiolite sample calcined at 200 °C has a higher adsorption capacity than the other calcined samples. Adsorption isotherms of PAM onto sepiolite have been determined and correlated with common isotherm equations such as Langmuir and Freundlich isotherm models. The Langmuir isotherm model appeared to fit the isotherm data better than the Freundlich isotherm model. The physical properties of this adsorbent are consistent with the parameters obtained from the isotherm equations. The zeta potentials of sepiolite suspensions have been measured in aqueous solutions of NaCl and different PAM concentrations and pH. From the experimental results: (i) pH strongly alters the zeta potential of sepiolite, (II) sepiolite has an isoelectric point at about pH 6.6 in water and about pH 8 in 250 mg L⁻¹ PAM concentration, (iii) PAM changes the interface charge from negative to positive for sepiolite. Effect of temperature on adsorption has been quantified by calculating various thermodynamic parameters such as Gibbs free energy, enthalpy and entropy. The dimensionless separation factor (R_L) has shown that sepiolite can be used for adsorption of PAM from aqueous solutions.

Keywords: Adsorption, Polyacrylamide, Sepiolite, Adsorption Isotherms, Calcination, Zeta Potential

? Kumar, K.V. and Sivanesan, S. (2006), Equilibrium data, isotherm parameters and process design for partial and complete isotherm of methylene blue onto activated carbon. Journal of Hazardous Materials, 134 (1-3), 237-244.

Full Text: 2006\J Haz Mat134, 237.pdf

Abstract: Equilibrium data for the adsorption of methylene blue onto activated carbon was reported. The equilibrium data were splitted to different data sets to have an idea on the partial and complete isotherm. The equilibrium data were analyzed using Freundlich, Langmuir and Redlich–Peterson isotherm. The influence of partial isotherm and complete isotherm on the equilibrium parameters in isotherm expression were estimated. Equilibrium data covering the complete isotherm is the best way to obtain the parameters in isotherm expressions. Present investigation showed that for successful batch sorber design, equilibrium data with partial isotherm is not sufficient, instead equilibrium data that covers complete isotherm is required. Redlich–Peterson and Langmuir isotherm well represent the adsorption of methylene blue onto activated carbon. Redlich–Peterson isotherm is a special case of Langmuir when the constant ‘g’ equals unity.

Keywords: Adsorption, Methylene Blue, Activated Carbon, Isotherm, Partial Isotherm, Complete Isotherm, Equilibrium Data, Process Design

? Pérez-Quintanilla, D., del Hierro, I., Fajardo, M. and Sierra, I. (2006), 2-Mercaptothiazoline modified mesoporous silica for mercury removal from aqueous media. Journal of Hazardous Materials, 134 (1-3), 245-256.

Full Text: 2006\J Haz Mat134, 245.pdf; 2006\J Haz Mat134, 245-1.pdf

Abstract: Mesoporous silicas (SBA-15 and MCM-41) have been functionalized by two different methods. Using the heterogeneous route the silylating agent, 3-chloropropyltriethoxysilane, was initially immobilized onto the mesoporous silica surface to give the chlorinated mesoporous silica Cl-SBA-15 or Cl-MCM-41. In a second step a multifunctionalized N, S donor compound (2-mercaptothiazoline, MTZ) was incorporated to obtain the functionalized silicas denoted as MTZ-SBA-15-Het or MTZ-MCM-41-Het. Using the homogeneous route, the functionalization was achieved via the one step reaction of the mesoporous silica with an organic ligand containing the chelating functions, to give the modified mesoporous silicas denoted as MTZ-SBA-15-Hom or MTZ-MCM-41-Hom. The functionalized mesoporous silicas were employed as adsorbents for the regeneration of aqueous solutions contaminated with Hg(II) at room temperature. SBA-15 and MCM-41 functionalized with MTZ by the homogeneous method present good mercury adsorption values (1.10 and 0.7 mmol Hg(II)/g of silica, respectively). This fact suggests a better applicability of such mesoporous silica supports to extract Hg(II) from aqueous solutions. In addition, it was observed the existence of a correlation between mercury adsorption with pore size and volume since, SBA-15 with lower areas and higher pore sizes functionalized with sterically demanding ligands, show better adsorption capacities than functionalized MCM-41.

Keywords: Functionalized Mesoporous Silica, Mercury Adsorption, 2-Mercaptothiazoline

? Srivastava, V.C., Mall, I.D. and Mishra, I.M. (2006), Characterization of mesoporous rice husk ash (RHA) and adsorption kinetics of metal ions from aqueous solution onto RHA. Journal of Hazardous Materials, 134 (1-3), 257-267.

Full Text: 2006\J Haz Mat134, 257.pdf

Abstract: The present study deals with the characterization of low-cost rice husk ash (RHA) for its various physico-chemical properties and adsorption characteristics of metal ions. The average particle size of RHA was 150.47 μm. Proximate analysis showed the presence of high amount of ash in RHA. Bulk density and the heating value of RHA were 104.9 kg/m³ and 9.68 MJ/kg, respectively. The pore size distribution results showed that the RHA was predominantly mesoporous. The BET surface area was 36.44 m²/g. The average pore diameter by BET was 42.603 Å. The BJH pore area showed 80% of the pore area due to the mesopores. The polar groups present on the RHA surface imparted considerable cation exchange capacity to it. RHA was found to be an effective adsorbent for the removal of cadmium (Cd(II)), nickel (Ni(II)) and zinc (Zn(II)) metal ions from aqueous solutions. The pH₀ ≈6.0 is found to be the optimum for the removal of individual cations from the aqueous solutions by RHA at an optimum dose of 10 kg/m³. The kinetics of adsorption showed that the metal ions adsorption on RHA is a gradual process with quasi-equilibrium being attained in 5 h. The pseudo-second-order kinetics represents the equilibrium data well. The effective diffusion coefficient of the cations onto the RHA is of the order of 10⁻¹³ m²/s.

Keywords: Adsorbent, Adsorption, Adsorption Kinetics, Analysis, Aqueous Solution, Aqueous Solutions, Bet, Bet Surface Area, Cadmium, Cadmium(II), Capacity, Cation, Cation Exchange, Characteristics, Characterization, Data, Diffusion, Diffusion Coefficient, Distribution, Equilibrium, Kinetics, Kinetics Of Adsorption, Mesoporous, Mesoporous Material, Metal, Metal Ions, Metal Removal, Nickel, Nickel(II), Particle Size, Pseudo Second Order, Pseudo Second Order Kinetics, Pseudo-Second-Order, Pseudo-Second-Order Kinetics, Removal, Rice, Rice Husk, Rice Husk Ash, Rice Husk Ash (RHA), Size, Solution, Solutions, Surface, Surface Area, Value, Zinc, Zinc(II)

? Kumar, K.V. and Sivanesan, S. (2006), Selection of optimum sorption kinetics: Comparison of linear and non-linear method. Journal of Hazardous Materials, 134 (1-3), 277-279.

Full Text: 2006\J Haz Mat134, 277.pdf

Abstract: Comparison of linear least-squares method and a trial and error non-linear method of estimating the kinetic parameters was examined to the experimental data of methylene blue onto activated carbon. Two most commonly used kinetic equations first order kinetics and pseudo second order kinetics was used to analyze the experimental data. The four different form of Ho’s pseudo second order kinetic was also discussed. Present investigation showed that the non-linear analysis method as more appropriate method to determine the rate kinetic parameters.

Keywords: Activated Carbon, Analysis, Aqueous-Solution, Carbon, Data, Dyes, Error, Experimental, First, First Order, Investigation, Ions, Kinetic, Kinetic Equations, Kinetic Parameters, Kinetics, Linear Method, Methylene Blue, Non-Linear Analysis, Non-Linear Method, Nonlinear Analysis, Peat, Pseudo, Pseudo Second Order, Pseudo Second Order Kinetic, Pseudo Second Order Kinetics, Pseudo-Second-Order, Rights, Second Order, Second Order Kinetics, Second-Order, Sorption, Sorption Kinetics, Trial

? Gheju, M. and Iovi, A. (2006), Kinetics of hexavalent chromium reduction by scrap iron. Journal of Hazardous Materials, 135 (1-3), 66-73.

Full Text: 2006\J Haz Mat135, 66.pdf

Abstract: The kinetics of Cr(VI) reduction by scrap iron was investigated in batch system, for aqueous solutions having low buffering capacities, as a function of pH (2.10–7.10), temperature (10–40 °C) and Cr(VI) concentration (19.2–576.9 μM). The results obtained using only the experimental data at initial times indicate zero-order kinetics at pH 2.10 and first-order kinetics over the pH range of 2.98–7.10. The reaction order with respect to H⁺ concentration, over the pH range of 4.17–7.10 and Cr(VI) concentration range of 19.2–38.4 μM, was found to be 0.31. The effects of pH, Cr(VI) initial concentration and temperature were investigated; the observed Cr(VI) reduction rates increased with decreasing pH, increasing temperature and decreasing initial Cr(VI) concentration. The observed and overall rate coefficients were determined, and a kinetic expression was developed to describe reduction of chromium by scrap iron over the pH range of 4.17–7.10 and Cr(VI) concentration range of 19.2–38.4 μM.

Keywords: Chromium(VI), Toxic Metals, Scrap Iron, Reduction Kinetics, Wastewater Treatment

? Uslu, G. and Tanyol, M. (2006), Equilibrium and thermodynamic parameters of single and binary mixture biosorption of Lead(II) and copper(II) ions onto Pseudomonas putida: Effect of temperature. Journal of Hazardous Materials, 135 (1-3), 87-93.

Full Text: 2006\J Haz Mat135, 87.pdf

Abstract: The biosorption of Lead(II) and copper(II) ions, single component and binary systems, by dried P. putida was investigated in a batch system. The effects of initial pH, temperature, initial single and binary mixture concentrations on the biosorption kinetics and equilibrium uptake of each component, both single and binary mixtures were investigated. The bacterial biomass exhibited the highest single and binary Lead(II) and copper(II) ions uptake capacity at 25 and 30 °C, respectively, the initial pH value of 5.5 and at the initial metal ions concentration of 100 mg dm⁻³. The Freundlich and Langmuir adsorption models were used for the mathematical description of the biosorption equilibrium and isotherm constants were evaluated at different temperatures. Adsorption data were well described by the Langmuir model, although they could be modeled by the Freundlich equation. The thermodynamics constants of the adsorption process: ΔH°, ΔS° and ΔG° were evaluated. The results showed that biosorption of single and binary Lead(II) ions on P. putida were exothermic and spontaneous. While biosorption of single and binary copper(II) ions on P. putida was endothermic and spontaneous.

Keywords: P. Putida, Biosorption, Single and Binary Lead(II)–Copper(II) Ions, Isotherms, Thermodynamics

? Aroğuz, A.Z. (2006), Kinetics and thermodynamics of adsorption of azinphosmethyl from aqueous solution onto pyrolyzed (at 600°C) ocean peat moss (Sphagnum sp.). Journal of Hazardous Materials,