Personal Research Database

Full Text: J\J Haz Mat109, 191.pdf

Abstract: Funalia trogii biomass was immobilized in Ca-alginate gel beads. The live and heat inactivated immobilized forms were used for the biosorption of Hg²⁺, Cd²⁺ and Zn²⁺ ions by using plain Ca-alginate gel beads as a control system. The effect of pH was investigated and the maximum adsorption of metal ions on the Ca-alginate and both live and inactivated immobilized fungal preparations were observed at pH 6.0. The temperature change between 15 and 45°C did not affect the biosorption capacity. The biosorption of Hg²⁺, Cd²⁺ and Zn²⁺ ions on the Ca-alginate beads and on both immobilized forms was studied in aqueous solutions in the concentration range of 30–600 mg/L. The metal biosorption capacities of the heat inactivated immobilized F. trogii for Hg²⁺, Cd²⁺ and Zn²⁺ were 403.2, 191.6, and 54.0 mg/g, respectively, while Hg²⁺, Cd²⁺ and Zn²⁺ biosorption capacities of the immobilized live form were 333.0, 164.8 and 42.1 mg/g, respectively. The same affinity order on a molar basis was observed for single or multi-metal ions (Hg²⁺>Cd²⁺>Zn²⁺). The Langmuir and the Freundlich type models were found to exhibit good fit to the experimental data. The experimental data were analyzed using the first-order (Langergren equations) and the second order (Ritchie equations). The experimental biosorption capacity with time is found to be best fit the second-order equations. The alginate-fungus system could be regenerated by washing with a solution of hydrochloride acid (10 mM). The percent desorption achieved was as high as 97. The biosorbents were reused in five biosorption–desorption cycles without significant loss of their initial biosorption capacity.

Keywords: Adsorption, Aqueous-Solution, Biosorption, Ca-Alginate, Elovich Equation, Funalia Trogii, Heavy Metal Ions, Heavy-Metals, Immobilized Biomass, Ions, Kinetic-Analysis, Marine-Algae, Mucor-Rouxii, Removal, Sphaerotilus-Natans, Trametes-Versicolor

Demirbas, A. (2004), Adsorption of lead and cadmium ions in aqueous solutions onto modified lignin from alkali glycerol delignication. Journal of Hazardous Materials, 109 (1-3), 221-226.

Full Text: J\J Haz Mat109, 221.pdf

Abstract: Adsorptions of toxic metal ions (Pb(II) and Cd(II)) onto modified lignin from beech and poplar woods by alkali glycerol delignification are presented in this paper. The material exhibits good adsorption capacity and the adsorption data follow the Langmuir model. The maximum adsorption capacities are 8.2-9.0 and 6.7-7.5 mg/g of the modified lignin for Pb(II) and Cd(II), respectively. The maximum adsorption percentage is 95.8 for Pb(II) for 4 h at 330 K and is 95.0 for Cd(II) for 10 h at 290 K. The adsorption of both the metal ions increased with increasing temperature indicating endothermic nature of the adsorption process. The maximum adsorption percentages of Pb(II) and Cd(II) ions decrease with time till 48 and 42 h and then again increase slightly with time. The adsorption of both heavy metal ions increases with pH. The adsorption of Pb(II) ions reached a maximum at a 5.0 value of pH. (C) 2004 Elsevier B.V. All rights reserved.

Keywords: Adsorption, Cadmium, Capacity, Cd(II), Delignification, Heavy Metal, Heavy Metal Ions, Heavy-Metal Ions, Langmuir, Lead, Lignin, Mercury, Metal Ions, Model, Modified, Modified Lignin, Paper, Pb(II), pH, Pinus-Pinaster Bark, Removal, Scavengers, Sorption, Temperature, Toxic Metal, Wastes, Water, Zinc

Inglezakis, V.J. and Grigoropoulou, H. (2004), Effects of operating conditions on the removal of heavy metals by zeolite in fixed bed reactors. Journal of Hazardous Materials, 112 (1-2), 37-43.

Full Text: J\J Haz Mat112, 37.pdf

Abstract: This work investigates the effects of flow rate (5-15 Bed Volumes, h), particle size (0.8-1.7 mm), concentration (0.005-0.02 N) and Na⁺-enrichment of natural clinoptilolite on the removal efficiency of Pb²⁺, Cu²⁺, Fe³⁺ and Cr³⁺ in aqueous solutions. Ion exchange is performed in an upflow fixed bed reactor. The removal efficiency is increased with decreasing flow rate, particle size and concentration and is improved by a factor of 2-10, depending on the specific metal. The modification of the natural sample is favorable, leading to an increase of removal efficiency by 32-100%. For the experimental conditions examined, removal efficiency order is the following: Pb²⁺ > Cr³⁺ > Fe³⁺ greater than or equal to Cu²⁺. Finally, the operation is influenced by the studied parameters, following the order: concentration > volumetric flow rate > particle size > modification of the material. (C) 2004 Elsevier B.V. All rights reserved.

Keywords: Adsorbers, Ammonia Removal, Cadmium, Clinoptilolite, Design, Fixed Bed, Heavy Metals, Ion Exchange, Ion-Exchange, Lead, Natural Clinoptilolite, Pretreatment, Recovery, Selectivity, Verification

? Huang, W.J. and Lo, J.S. (2004), Synthesis and efficiency of a new chemical fixation agent for stabilizing MSWI fly ash. Journal of Hazardous Materials, 112 (1-2), 79-86.

Full Text: 2004\J Haz Mat112, 79.pdf

Abstract: In this study, a novel chemical fixation agent, colloidal aluminate oxide (CAO), has been synthesized and characterized in detail. CAO does not require cementitious additives, and can be used as a stabilizer of lead in the fly ash from municipal solid waste incineration (MSWI) plants. CAO reveals a high reduction ratio for the leachability of Pb of 94.8% when compared with three commercial fixation agents, MF-103, BTS-03 and POCAT and two fine chemicals, ethylene diaminetetracetic acid (EDTA) and thiodiglycolic acid (TGA). A possible mechanism for CAO stabilization of lead is formulated based on the results of Fourier-transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) spectra. (C) 2004 Elsevier B.V. All rights reserved.

Keywords: Fly Ash, Stabilization, Lead, Chelator, Aqueous Solubility Diagrams, Lead Immobilization, Degradation, Systems

Bektaş, N., Ağım, B.A. and Kara, S. (2004), Kinetic and equilibrium studies in removing lead ions from aqueous solutions by natural sepiolite. Journal of Hazardous Materials, 112 (1-2), 115-122.

Full Text: J\J Haz Mat112, 115.pdf

Abstract: The capacity of sepiolite for the removal of lead ions from aqueous solution was investigated under different experimental conditions. The Langmuir and Freundlich equations, which are in common use for describing sorption equilibrium for wastewater-treatment applications, were applied to data. The constants and correlation coefficients of these isotherm models for the present system at different conditions such as pH, temperature and particle size were calculated and compared. The equilibrium process was well described by the Langmuir isotherm model and the maximum sorption capacity was found to be 93.4 mg/g for the optimal experimental condition. The thermodynamic parameters (ΔG°, ΔH° and ΔS°) for lead sorption on the sepiolite were also determined from the temperature dependence. The influences of specific parameters such as the agitation speed, particle size and initial concentration for the kinetic studies were also examined. The sorption kinetics were tested for first order reversible, pseudo-first order and pseudo-second order reaction and the rate constants of kinetic models were calculated. The best correlation coefficients were obtained using the pseudo-second order kinetic model, indicating that lead uptake process followed the pseudo-second order rate expression.

Keywords: Agitation, Aqueous Solution, Aqueous Solutions, Capacity, Concentration, Correlation, Data, Equilibrium, Equilibrium Studies, Experimental, Expression, First, First Order, Freundlich, Isotherm, Isotherm Model, Kinetic, Kinetic Model, Kinetic Modelling, Kinetic Models, Kinetic Studies, Kinetics, Langmuir, Langmuir Isotherm, Langmuir Isotherm Model, Lead, Lead Removal, Model, Models, Particle Size, pH, 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, Rate Constants, Removal, Sepiolite, Size, Solution, Solutions, Sorption, Sorption Capacity, Sorption Kinetics, Temperature, Thermodynamic, Thermodynamic Parameters, Uptake, Wastewater Treatment

Hamadi, N.K., Swaminathan, S. and Chen, X.D. (2004), Adsorption of Paraquat dichloride from aqueous solution by activated carbon derived from used tires. Journal of Hazardous Materials, 112 (1-2), 133-141.

Full Text: J\J Haz Mat112, 133.pdf

Abstract: The removal of pesticide from wastewater under different batch experimental conditions, using a car tire derived activated carbon was investigated. The pesticide utilized in the study was Paraquat dichloride (1,1-dimethyl-4,4-bipyridyl dichloride), which is a well known herbicide. The adsorbent was produced from the pyrolysis and activation of used tires (TAC). The performances of this adsorbent and a commercial activated carbon F300 (CAC) have been compared. It was determined that the adsorption of Paraquat was weakly pH dependent. The effects of particle size, carbon dosage, temperature and the initial concentration of the Paraquat were studied. Further experiments investigating the regeneration capabilities of the tire-supplied carbon were performed. The regenerated carbons that were washed with basic pH solution were found to have the best sorption capacity recovery.

It was found that the rate of sorption of Paraquat onto the carbon is very fast with almost 90% of the maximum possible adsorption taking place in the first 5 min. Nevertheless, the batch sorption kinetics was fitted for a first-order reversible reaction, a pseudo-first-order reaction and a pseudo-second-order reaction. The pseudo-second-order chemical reaction model appears to provide the best correlation. The applicability of the Langmuir isotherm for the present system has been evaluated at different temperatures. The isotherms show that the sorption capacity of CAC decreases with temperature and the dominant mechanism of CAC adsorption is physical sorption.

Keywords: 1,1-Dimethyl-4,4-Bipyridyl Dichloride, Activated Carbon, Activation, Adsorbent, Adsorption, Adsorption Kinetics, Aqueous Solution, Batch, Capacity, Carbon, Chemical, Concentration, Correlation, Experimental, Experiments, First, First Order, Herbicide, Isotherm, Isotherms, Kinetics, Langmuir, Langmuir Isotherm, Mechanism, Model, Paraquat, Paraquat Dichloride, Particle Size, Pesticide, pH, pH-Dependent, Physical, Pseudo First Order, Pseudo Second Order, Pseudo-First-Order, Pseudo-Second-Order, Pyrolysis, Recovery, Regeneration, Removal, Size, Solution, Sorption, Sorption Capacity, Sorption Kinetics, Temperature, Thermodynamic Parameters, Used Tires, Wastewater

Öztürk, N. and Bektaş, T.E. (2004), Nitrate removal from aqueous solution by adsorption onto various materials. Journal of Hazardous Materials, 112 (1-2), 155-162.

Full Text: J\J Haz Mat112, 155.pdf

Abstract: In this study sepiolite, sepiolite activated by HCl, slag and powdered activated carbon were used as adsorbent with a particle size was between 71 and 80 m (200–170 mesh). NaNO₃ solution (100 mg/l) was used in batch adsorption experiments for nitrate removal. First kinetic studies were carried out and it was determined that slag was not effective for nitrate removal, then contact time, pH and adsorbent dosage effects on nitrate removal by adsorption were investigated using other adsorbents except slag. The equilibrium time was found to be 30, 45, 5 min for sepiolite, powdered activated carbon and activated sepiolite, respectively. The most effective pH value for nitrate removal was 2 for powdered activated carbon. pH value did not affect nitrate removal significantly for other adsorbents. Adsorbent dosages were varied from 5 to 20 g/l solutions. An increase in adsorbent dosage increased the percent removal of nitrate. A series of isotherm studies were undertaken and the data evaluated for compliance with the Langmuir and Freundlich isotherm models. To investigate the adsorption mechanisms, three simplified kinetic models, i.e., first-, second-order and intraparticle diffusion were tested. Adsorption followed second-order rate kinetics. The correlation coefficients for second order kinetic model are greater than 0.996. Experimental data show that sepiolite activated by HCl was effective for nitrate removal.

Keywords: Nitrate Removal, Adsorption, Sepiolite, Activated Sepiolite, Wastewater

? Ayranci, E. and Hoda, N. (2004), Studies on removal of metribuzin, bromacil, 2,4-D and atrazine from water by adsorption on high area carbon cloth. Journal of Hazardous Materials, 112 (1-2), 163-168.

Full Text: 2004\J Haz Mat112, 163.pdf

Abstract: The removal of pesticides such as metribuzin, bromacil, 2,4-D and atrazine from aqueous solutions was studied by adsorption on high area carbon cloth. The adsorption process was followed by in situ UV-spectrophotometric technique in a specially designed adsorption cell. Spectroscopic data of the pesticides were determined in separate experiments. The extent of adsorption was quantified by calculating the amount of adsorbate adsorbed per unit area of the carbon cloth and the percentage coverage at the carbon-cloth surface. The order of extent of adsorption of the pesticides studied was found as metribuzin < 2,4-D < bromacil < atrazine. The adsorption process was found to follow a first-order kinetics and the rate constants were determined. The competitive adsorption of pesticides was also examined by carrying out the adsorption process from a solution of equimolar mixture of bromacil and metribuzin. (C) 2004 Elsevier B.V. All rights reserved.

Keywords: 2,4-D, Activated Carbon, Adsorption, Alumina, Anions, Atrazine, Carbon, Carbon Cloth, Competitive Adsorption, Coverage, Electrosorption, Felt Electrodes, First Order, Kinetics, Pesticides, Pesticides, Purification, Removal, Waste-Waters, Water Treatment

Aklil, A., Mouflih, M. and Sebti, S. (2004), Removal of heavy metal ions from water by using calcined phosphate as a new adsorbent. Journal of Hazardous Materials, 112 (3), 183-190.

Full Text: J\J Haz Mat112, 183.pdf

Abstract: Calcined phosphate (CP) has been employed in our laboratories as a heterogeneous catalyst in a variety of reactions. In this study, CP was evaluated as a new product for removal of heavy metals from aqueous solution. Removal of Pb²⁺, Cu²⁺, and Zn²⁺ on the CP was investigated in batch experiments. The kinetic of lead on CP adsorption efficiency and adsorption process were evaluated and analysed using the theories of Langmuir and Freundlich. The influence of pH was studied. The adsorption capacity obtained at pH 5 were 85.6, 29.8, and 20.6 mg g⁻¹ for Pb²⁺, Cu²⁺ and Zn²⁺, respectively. We hypothesize at pH 2 and 3, the dissolution of CP and precipitation of a fluoropyromorphite for lead and the formation of solid-solution type fluorapatite for copper. The results obtained show that CP is a good adsorbent for these toxic heavy metals. The abundance of natural phosphate, its low price and non-aggressive nature towards the environment are advantage for its utilisation in point of view of wastewater and wastes clean up.

Keywords: Natural Phosphate, Adsorption, Heavy Metal, Langmuir Isotherm, Freundlich Isotherm

Tel, H., Altaş, Y. and Taner, M.S. (2004), Adsorption characteristics and separation of Cr(III) and Cr(VI) on hydrous titanium(IV) oxide. Journal of Hazardous Materials, 112 (3), 225-231.

Full Text: J\J Haz Mat112, 225.pdf

Abstract: A hydrous titanium(IV) oxide was prepared to study the adsorption characteristics and the separation of chromium species. Batch sorption studies have been carried out to determine the effect of pH on the sorption of Cr(III) and Cr(VI) on hydrous TiO₂. An excellent separation efficiency of Cr(III) and Cr(VI) was obtained at pH 2. The adsorption percentage of Cr(VI) was above 99%, whereas that of the Cr(III) was less than 1% at this pH. The adsorption isotherm of Cr(VI) on hydrous TiO₂ at pH 2 was in good agreement with the Langmuir isotherm. The maximum adsorption capacity of Cr(VI) on TiO₂ was 5 mg g⁻¹. The rate of adsorption of Cr(VI) by hydrous TiO₂ with average particle diameter 250 and 500m has been studied under particle diffusion controlled conditions. The diffusion coefficients of Cr(VI) for both hydrous TiO₂ having average particle diameter of 250 and 500m was calculated at pH 2 as 3.84×10⁻¹⁰m²s⁻¹ and 8.86×10⁻¹⁰ m² s⁻¹, respectively.

Keywords: Chromium, Adsorption, Separation, Titanium Dioxide, Diffusion Coefficient

Starvin, A.M. and Prasada Rao, T. (2004), Removal and recovery of mercury(II) from hazardous wastes using 1-(2-thiazolylazo)-2-naphthol functionalized activated carbon as solid phase extractant. Journal of Hazardous Materials, 113 (1-3), 75-79.

Full Text: J\J Haz Mat113, 75.pdf

Abstract: As a part of removal of toxic heavy metals from hazardous wastes, solid phase extraction (SPE) of mercury(II) at trace and ultra trace levels was studied using 1-(2-thiazolylazo)-2-naphthol (TAN) functionalized activated carbon (AC). The SPE material removes traces of mercury(II) quantitatively in the pH range 6.0±0.2. Other parameters that influence quantitative recovery of mercury(II), viz. percent concentration of TAN in AC, amount of TAN–AC, preconcentration time and volume of aqueous phase were varied and optimized. The possible means of removal of Hg(II) from other metal ions that are likely to be present in the wastes of the chloroalkali industry is discussed. The potential of TAN-functionalized AC SPE material for decontaminating mercury from the brine sludge and cell house effluent of a chloralkali plant has been evaluated.

Keywords: Mercury(II), Solid Phase Extraction, 1-(2-Thiazolylazo)-2-Naphthol Functionalized Activated Carbon, Hazardous Chloralkali Industrial Wastes

Malik, P.K. (2004), Dye removal from wastewater using activated carbon developed from sawdust: Adsorption equilibrium and kinetics. Journal of Hazardous Materials, 113 (1-3), 81-88.

Full Text: J\J Haz Mat113, 81.pdf

Abstract: Mahogany sawdust was used to develop an effective carbon adsorbent. This adsorbent was employed for the removal of direct dyes from spent textile dyeing wastewater. The experimental data were analysed by the Langmuir and Freundlich models of adsorption. Equilibrium data fitted well with the Langmuir model. The rates of adsorption were found to conform to the pseudo-second-order kinetics with good correlation. The equilibrium adsorption capacity of the sawdust carbon was determined with the Langmuir equation as well as the pseudo-second-order rate equation and found to be >300 mg dye per gram of the adsorbent. The most ideal pH for adsorption of direct dyes onto sawdust carbon was found to be 3 and below. The results indicate that the Mahogany sawdust carbon could be employed as a low cost alternative to commercial activated carbon in the removal of dyes from wastewater.

Keywords: Activated Carbon, Adsorbent, Adsorption, Adsorption Capacity, Adsorption Equilibrium, Alternative, Capacity, Carbon, Correlation, Cost, Data, Direct Azo Dye, Dye, Dye Removal, Dyes, Equilibrium, Experimental, Freundlich, Isotherms, Kinetics, Langmuir, Langmuir Equation, Langmuir Model, Model, Models, pH, Pseudo Second Order, Pseudo Second Order Kinetics, Pseudo-Second-Order, Pseudo-Second-Order Kinetics, Pseudo-Second-Order Rate, Rates, Removal, Removal of Dyes, Sawdust, Wastewater

Bhattacharyya, K.G. and Sharma, A. (2004), Adsorption of Pb(II) from aqueous solution by Azadirachta indica (Neem) leaf powder. Journal of Hazardous Materials, 113 (1-3), 97-109.

Full Text: J\J Haz Mat113, 97.pdf

Abstract: An adsorbent was developed from the nature leaves of the Neem (Azadirachta indica) tree for removing Pb(II) from water. Adsorption was carried out in a batch process with several different concentrations of Pb(II) by varying amount of adsorbent, pH, agitation time and temperature. The uptake of the metal was very fast initially, but gradually slowed down indicating penetration into the interior of the adsorbent particles. Both first-order and second-order kinetics were tested and it was found that the latter gave a better explanation. The experimental data closely followed both Langmuir and Freundlich isotherms. The adsorbent had a considerably high Langmuir monolayer capacity of 300 mg/g. A small amount of the adsorbent (1.2 g/L) could remove as much as 93% of Pb(II) in 300 min from a solution of concentration 100 mg/L at 300 K. The adsorption continuously increased in the pH range of 2.0–7.0, beyond which the adsorption could not be carried out due to the precipitation of the metal. The adsorption was exothermic at ambient temperature and the computation of the parameters, ΔH, ΔS and ΔG, indicated the interactions to be thermodynamically favourable.

Keywords: Adsorbent, Adsorption, Agitation, Agitation Time, Ambient, Ambient Temperature, Aqueous Solution, Azadirachta Indica, Batch, Biogas Residual Slurry, Capacity, Color Removal, Computation, Concentration, Concentrations, Equilibrium, Exothermic, Experimental, Experimental Data, First Order, Fly-Ash, Freundlich, Freundlich Isotherms, Heavy-Metal Ions, Interactions, Isotherms, Kinetics, Kinetics, Langmuir, Langmuir and Freundlich Isotherms, Langmuir Monolayer, Lead, Leaf, Leaves, Metal, Monolayer, Monolayer Capacity, Neem Leaf Powder, Parameters, Particles, Pb(II), Peanut Hull Carbon, Penetration, pH, Powder, Precipitation, Process, Range, Removing, Second Order, Second Order Kinetics, Second-Order Kinetics, Silica-Gels, Sorption, Temperature, Time, Tree, Uptake, Waste-Water, Water

Akçay, M. and Akçay, G. (2004), The removal of phenolic compounds from aqueous solutions by organophilic bentonite. Journal of Hazardous Materials, 113 (1-3), 189-193.

Full Text: J\J Haz Mat113, 189.pdf

Abstract: The adsorption of p-chlorophenol (p-CP) and p-nitrophenol (p-NP) on organophilic bentonite (dodecylammonium bentonite, DDAB) was studied as a function of solution concentration and temperature. The observed adsorption rates were found to be equal to the first-order kinetics. The rate constants were calculated for temperatures ranging between 25.0–35.0°C at constant concentration. The adsorption energies, E and adsorption capacity, (q_m), for phenolic compounds adsorbed to organophilic bentonite were estimated by using the Dubinin-Radushkevic equation. Thermodynamic parameters from the adsorption isotherms of p-CP and p-NP on organophilic bentonite were determined. These isotherms were modeled according to Freundlich and Dubinin-Radushkevic adsorption isotherms and followed the V-shaped isotherm category with two steps. The amount of adsorption was found to be dependent on the relative energies of adsorbent–adsorbate, adsorbate–solvent and adsorbate–adsorbate interaction.

Keywords: Phenolic Compounds, Removal, Adsorption, Kinetics, Organophilic Clays, Hydrophobicity

Lin, S.H., Juang, R.S. and Wang, Y.H. (2004), Adsorption of acid dye from water onto pristine and acid-activated clays in fixed beds. Journal of Hazardous Materials, 113 (1-3), 195-200.

Full Text: J\J Haz Mat113, 195.pdf

Abstract: The adsorption of an acid dye from water onto pristine and HCl-activated montmorillonites in fixed beds was investigated. Experiments were carried out as a function of liquid flow rate, initial dye concentration, and bed height. The adsorption capacity of acid dye onto pristine clay could be largely improved when the clay was activated by HCl. A mass transfer model that involves only two parameters, τ (50% breakthrough time) and k (adsorption rate constant), was proposed. This model could satisfactorily describe the measured breakthrough curves of acid dye in fixed beds (standard deviation <6%). It was shown that the value of τ decreased with increasing liquid flow rate. The effect of the type of clay (pristine, acid-activated) on the values of k, τ, and adsorption capacity was discussed, and the application potential of acid-activated clay for adsorption removal of acid dye from water was also demonstrated.

Keywords: Acid Activated Clay, Acid Activation, Acid Dye, Adsorption, Adsorption Capacity, Adsorption Rate, Application, Bentonite, Breakthrough, Breakthrough Curve, Breakthrough Curves, Capacity, Carbon, Catalytic Activity, Clay, Clays, Concentration, Dye, Exchange, Fixed Bed, Flow, Flow Rate, Function, Ions, Kinetics, Liquid, Mass Transfer, Methylene-Blue, Model, Montmorillonite, Na⁺-Montmorillonite, Organic Contaminants, Potential, Pristine, Rate Constant, Removal, Rights, Standard, Value, Water

Erdem, M., Gür F. and Tümen, F. (2004), Cr(VI) reduction in aqueous solutions by siderite. Journal of Hazardous Materials,