Personal Research Database

Full Text: 2007\J Haz Mat139, 447.pdf

Abstract: Phosphates are very important basic materials in agricultural and other industrial applications. Phosphorus is often present in low concentrations in wastewater, almost solely in the form of organic and inorganic phosphates (ortho- and poly-phosphates). The removal of phosphates from surface waters is generally necessary to avoid problems, such as eutrophication, particularly near urban areas. The usual methods of treatment are either biological or physicochemical by sedimentation. This paper studies the removal of phosphate species by adsorption onto calcite used as natural adsorbent.

The phosphate solutions were prepared artificially by adding certain quantities of K₂HPO₄ in water. The effect of equilibrium pH, phosphate/mineral ratio and contact time was studied. The results showed that pH plays an important role in the removal of phosphate species from solution, with removal being more efficient in the basic pH region. The experimental results also show that adsorption is also efficient for high ratios phosphate/adsorbent. Finally, the adsorption process is time dependant. Based on the experimental results a possible mechanism of phosphate removal onto calcite surface is proposed.

As a general conclusion, phosphate species seem to be efficiently removed from solutions using calcite as natural adsorbent. In addition, the adsorption product can be used as fertilizer for acid soils.

Keywords: Acid, Adsorbent, Adsorbents, Adsorption, Adsorption Process, Agricultural, Applications, Aqueous-Solutions, Calcite, Concentrations, Environment, Equilibrium, Eutrophication, Goethite, Industrial, Inorganic, Liquid Effluents Purification, Materials, Mechanism, Methods, Natural, Natural Adsorbent, Organic, Orthophosphates Adsorption, Paper, pH, Phosphate, Phosphates, Phosphorus Removal, Removal, Role, Sedimentation, Slag, Soils, Sorption, Surface, Surface Waters, Treatment, Urban, Urban Areas, Waste-Water Treatment, Wastewater, Water, Waters

? Marchat, D., Bernache-Assollant, D. and Champion, E. (2007), Cadmium fixation by synthetic hydroxyapatite in aqueous solution: Thermal behaviour. Journal of Hazardous Materials, 139 (3), 453-460.

Full Text: 2007\J Haz Mat139, 453.pdf

Abstract: This study deals with the mechanism of the cadmium uptake by synthetic hydroxyapatite (HA: Ca₁₀(PO₄)₆(OH)₂) in aqueous solution. The rate of cadmium fixation by hydroxyapatite was investigated at 10 and 50 °C using batch experiments. Inductively coupled plasma atomic emission spectrometry, X-ray diffraction, FT-IR spectroscopy and electron microscopy were used to characterize the starting HA and the samples. The thermal behaviour of the powders was determined with the help of three thermoanalytical techniques (TGA, DTA, and MS) and temperature programmed X-ray diffraction. Cadmium immobilization kinetics can be divided into two steps: substitution of Ca²⁺ ions by Cd²⁺ in the HA lattice at the particle’s surface, followed by their incorporation into the hydroxyapatite bulk. This results in the formation of an apatite solid solution, which is very important because in this way decontamination and storage can be performed with the same material.

Keywords: Hydroxyapatite, Cadmium, Ion Exchange, Solid Solution

? Garg, U.K., Kaur, M.P., Garg, V.K. and Sud, D. (2007), Removal of hexavalent chromium from aqueous solution by agricultural waste biomass. Journal of Hazardous Materials, 140 (1-2), 60-68.

Full Text: 2007\J Haz Mat140, 60.pdf

Abstract: In the present study adsorption of Cr(VI) from aqueous solutions onto different agricultural wastes, viz., sugarcane bagasse, maize corn cob and Jatropha oil cake under various experimental conditions has been studied. Effects of adsorbent dosage, Cr(VI) concentration, pH and contact time on the adsorption of hexavalent chromium were investigated. The concentration of chromium in the test solution was determined spectrophotometrically. FT-IR spectra of the adsorbents (before use and after exhaustion) were recorded to explore number and position of the functional groups available for the binding of chromium ions on to studied adsorbents. SEMs of the adsorbents were recorded to explore the morphology of the studied adsorbents. Maximum adsorption was observed in the acidic medium at pH 2 with a contact time of 60 min at 250 rpm stirring speed. Jatropha oil cake had better adsorption capacity than sugarcane bagasse and maize corn cob under identical experimental conditions. The applicability of the Langmuir and Freundlich adsorption isotherms was tested. The results showed that studied adsorbents can be an attractive low cost alternative for the treatment of wastewaters in batched or stirred mode reactors containing lower concentrations of chromium.

Keywords: Activated Carbon, Adsorbent, Adsorbents, Adsorption, Adsorption Capacity, Adsorption Isotherms, Agricultural, Batch, Binding, Biomass, Biosorption, Capacity, Chromium, Chromium Ions, Chromium(VI), Concentration, Concentrations, Corn, Cost, Cr(VI), Cr(VI) Removal, Dosage, Freundlich, FT-IR, FTIR, Functional Groups, Groups, Hexavalent Chromium, Isotherms, Jatropha Oil Cake, Langmuir, Maize, Maize Corncob, Morphology, Oil, pH, Position, Sawdust, SEM, Speed, Sugarcane, Sugarcane Bagasse, Test, Treatment, Waste, Wastes, Wastewaters

? Arpat, E., Sayilkan, F., Asiltürk, M., Tatar, P., Kiraz, N. and Sayilkan, H. (2007), Photocatalytic performance of Sn-doped and undoped TiO₂ nanostructured thin films under UV and vis-lights. Journal of Hazardous Materials, 140 (1-2), 69-74.

Full Text: 2007\J Haz Mat140, 69.pdf

Abstract: Sn-doped and undoped nano-TiO₂ particles have been synthesized by hydrotermal process without solvent at 200C in 1 h. Nanostructure-TiO₂ based thin films have been prepared on glass substrate by spin-coating technique. The structure, surface morphology and optical properties of the thin films and the particles have been investigated by element analysis and XRD, SEM, BET and UV-vis-NIR techniques. The photocatalytic performance of the films were tested for degradation of Malachite Green dye in solution under UV and vis-lights. The results showed that (a) hydrothermally synthesized nano-TiO₂ particles are fully anatase crystalline form and are easily dispersed in water, (b) the coated surfaces have nearly super-hydrophilic properties and, (c) the doping of transition metal ion efficiently improved the photocatalytic performance of the TiO₂ thin film.

Keywords: Analysis, Anatase, BET, Coated, Degradation, Dye, Glass, Malachite Green, Malachite-Green, Metal, Morphology, Nano-TiO₂, Optical Properties, Particles, Performance, Photocatalysis, Photocatalytic, SEM, Sn-Doping, Solution, Structure, Surface, Surfaces, Techniques, Thin Film, TiO₂, UV, Water, XRD

? Baraka, A., Hall, P.J. and Heslop, M.J. (2007), Melamine-formaldehyde-NTA chelating gel resin: Synthesis, characterization and application for copper(II) ion removal from synthetic wastewater. Journal of Hazardous Materials, 140 (1-2), 86-94.

Full Text: 2007\J Haz Mat140, 86.pdf

Abstract: A new chelating resin was synthesised by anchoring nitrilotriacetic acid (NTA) to melamine during the melamine-formaldehyde gelling reaction in the presence of water, using acetone and guaiacol as a porogen mixture. This technique gives a porous chelating gel resin capable of removing heavy metals from wastewater. FT-IR, XRD, elemental analysis, surface area and water regain measurements were conducted for characterization of the new chelating gel resin. A comprehensive adsorption study (kinetics isotherm, and thermodynamics) of Cu(II) removal from synthetic acidic aqueous solutions by adsorption on this resin was conducted regarding the effects of time, temperature, initial pH and copper(II) initial concentration. (c) 2006 Elsevier B.V. All rights reserved.

Keywords: Acetone, Acid, Acidic, Activated Carbon, Adsorption, Adsorption Properties, Analysis, Application, Aqueous Solutions, Aqueous-Solutions, Cation-Exchange, Characterization, Chelating Adsorption, Chelating Resin, Concentration, Copper(II), Cu(II), Cu(II) Removal, Effects, Exchange Properties, FT-IR, FTIR, Gel, Heavy Metals, Heavy-Metal Ions, Isotherm, Kinetics, Melamine-Formaldehyde-Nta Resin, Metals, Mixture, pH, Polymer, Porogen, Presence, Removal, Resin, Rights, Solutions, Surface, Surface Area, Synthesis, Technique, Temperature, Thermodynamics, Time, Wastewater, Water, XRD

? Banerjee, P., DasGupta, S. and De, S. (2007), Removal of dye from aqueous solution using a combination of advanced oxidation process and nanofiltration. Journal of Hazardous Materials, 140 (1-2), 95-103.

Full Text: 2007\J Haz Mat140, 95.pdf

Abstract: In order to have energy and cost effective separation of dyes, a combination of advanced oxidation process (AOP) using Fenton’s reagent and nanofiltration (NF) is proposed. Three combinations of AOP and NF are studied using a synthetic solution of eosin dye. Scheme-1 is AOP followed by NF. Scheme-2 is NF followed by AOP. and Scheme-3 is two-step NF. The concentration of eosin dye studied in the first step of each of the schemes is in the range of 70–200 mg/l. The operating transmembrane pressures for NF steps are 552, 689 and 828 kPa. The crossflow velocities are 0.46, 0.69 and 0.91 m/s. The schemes are compared for permeate flux, permeate concentration and duration of operation. In Scheme-1, AOP is conducted for 30 min, and then subjected to NF, whereas in Scheme-2, the time needed for AOP is more than 3 h to achieve the concentration level of the dye below 1 mg/l. Thus, it is found that Scheme-1 is superior to Scheme-2 due to lesser time requirement. However, Scheme-3 involving no AOP, is also suitable for dye separation as the final eosin concentration in the permeate falls below 1 mg/l. Scheme-1 is found suitable for dye concentration of 70 mg/l and the most appropriate composition of Fenton’s reagent is 1665 mg/l of H₂O₂ and 347.5 mg/l of FeSO₄·7H₂O. Suitable NF operating conditions in step 2 of Scheme-1 is transmembrane pressure of 689 kPa and crossflow velocity of 0.91 m/s. In Scheme-3, the suitable operating conditions for NF in both the steps are 828 kPa transmembrane pressure and 0.91 m/s crossflow velocity. Scheme-2 is found to be unsuitable.

Keywords: Advanced Oxidation, Advanced Oxidation Process, China, Composition, Concentration, Cost, Decolorization, Dye, Dyes, Energy, Eosin Y Dye, Fenton’s Reagent, Fentons Reagent, Flux, Membranes, Nanofiltration, Operating Conditions, Oxidation, Permeate Flux, Preoxidation, Pressure, Range, Retention, Separation, Textile-Industry, Waste-Water Treatment

? Benhammou, A., Yaacoubi, A., Nibou, L. and Tanouti, B. (2007), Chromium(VI) adsorption from aqueous solution onto Moroccan Al-pillared and cationic surfactant stevensite. Journal of Hazardous Materials, 140 (1-2), 104-109.

Full Text: 2007\J Haz Mat140, 104.pdf

Abstract: Batch adsorption of the chromium(VI) onto Moroccan stevensite pillared by Keggin aluminium hydroxypolycation (Al-stevensite) and cationic surfactant cetyltrimethylammoniumbromide (CTA-stevensite) was investigated. The results showed that the CTA-stevensite has a higher affinity than that of Al-stevensite for chromium(VI) adsorption. The adsorption capacities for natural stevensite, Al-stevensite and CTA-stevensite calculated according to the Dubinin-Kaganer-Radushkevich isotherm (DKR) are 13.7, 75.4 and 195.6 mmol kg^-1, respectively. The study of the pH effect showed that the optimal range corresponding to the Cr(VI) maximum adsorption on Al-stevensite is pH 3.5-6 and that on CTA-stevensite is pH 2-6. The adsorption rates evaluated according to the pseudo-second-order model are 7.2, 207.2 and 178.5 mmol kg^-1 min^-1 for the natural stevensite, Al-stevensite and CTA-stevensite, respectively. The low values of the adsorption energy calculated by (DKR) suggest that anion exchange is the main mechanism that governs the chromate adsorption. (c) 2006 Elsevier B.V. All rights reserved.

Keywords: Adsorption, Adsorption Mechanism, Aluminium, Anion Exchange, Anionic Contaminants, Cationic Surfactant, Chromate, Chromate Adsorption, Chromate Reduction, Chromium(VI), Cr(VI), Energy, Ions, Isotherm, Kaolinite, Kinetic, Mechanism, Minerals, Model, Modified Clay, Montmorillonite, Moroccan Stevensite, Natural, pH, Pillared, Pseudo-Second-Order, Range, Removal, Soil, Sorption, Surfactant

? Birlik, E., Ersöz, A., Açıkkalp, E., Denizli, A. and Say, R. (2007), Cr(III)-imprinted polymeric beads: Sorption and preconcentration studies. Journal of Hazardous Materials, 140 (1-2), 110-116.

Full Text: 2007\J Haz Mat140, 110.pdf

Abstract: The purpose of this study is to prepare a novel molecular imprinted adsorbent to Cr(III) analysis with high selectivity. Initially, Chromium(III)-methacryloylhistidine (MAH/Cr(III)) complex monomer was synthesized and then Cr(III) ion imprinted ethyleneglycoldimethacrylate-methacryloylhistidine (poly(EDMA-MAH/Cr(III))) was polymerized. Cr(III) ions were removed from the Cr(III)imprinting polymer. Selective cavity for the Chromium(III) ions was obtained in the (poly(EDMA-MAH/Cr(III))) beads. These Cr(III)-imprinted beads were used in the sorption-desorption process. The effect of initial concentration of metal, the sorption rate and the pH of the medium on sorption capacity of Cr(III)-imprinting sorbents were studied. Sorption equilibrium time was achieved in about 30 min. The maximum sorption of Cr(HI) ions onto imprinted beads was about 69.28 mg/g. Sorption studies of CO(H), Ni(II), Cr(III) and Cr(VI) ions were also investigated using Cr(III)-imprinting polymers. The obtained results show that selectively adsorbed amount of Cr(III) ion on Cr(III)-imprinting polymers is higher than all other studied ions. When the beads were used repeatedly, their adsorption capacity was showed feasibility. (c) 2006 Elsevier B.V. All rights reserved.

Keywords: Adsorbent, Adsorption, Adsorption Capacity, Analysis, Aqueous-Solutions, Beads, Capacity, Chromatography, Chromium, Chromium Preconcentration, Complex, Concentration, Cr(VI), Equilibrium, Heavy-Metal Ions, Ion, Metal, Microbeads, Molecular Imprinting, Molecularly Imprinted Polymers, pH, Polymer, Polymeric, Polymers, Preconcentration, Removal, Selectivity, Separation, Solid-Phase Extraction, Sorption, Sorption Capacity, Waste-Water

? Özcan, A., Ömeroğlu, Ç., Erdoğan, Y. and Özcan, A.S. (2007), Modification of bentonite with a cationic surfactant: An adsorption study of textile dye Reactive Blue 19. Journal of Hazardous Materials, 140 (1-2), 173-179.

Full Text: 2007\J Haz Mat140, 173.pdf

Abstract: The utilization of modified bentonite with a cationic surfactant (dodecyltrimethylammonium (DTMA) bromide) as an adsorbent was successfully carried out to remove a synthetic textile dye (Reactive Blue 19 (RB19)) by adsorption, from aqueous solutions. Batch studies were carried out to address various experimental parameters such as pH, contact time and temperature. The surface modification of bentonite with surfactant was examined using the FTIR spectroscopic technique and elemental analysis. Effective pH for the adsorption of RB19 onto DTMA-bentonite was around 1.5. The Langmuir isotherm model was found to the best represent the equilibrium with experimental data. The maximum adsorption capacity (qmax) has been found to be 3.30×10^–4 mol g^–1 or 206.58 mg g^–1. The thermodynamic study indicated that the adsorption of RB19 onto DTMA-bentonite was favored with the negative Gibbs free energy values. The pseudo-second-order rate equation was able to provide the best description of adsorption kinetics and the intraparcticle diffusion model was also applicable up to 40 min for the adsorption of RB19 onto DTMA-bentonite.

Keywords: Acid Dye, Acid-Blue-193, Adsorbent, Adsorption, Adsorption Capacity, Adsorption Kinetics, Analysis, Aqueous Solutions, Aqueous-Solutions, Azo Dyes, Bentonite, Bottom Ash, Bromide, Capacity, Cationic Surfactant, Data, Diffusion, Diffusion Model, Dye, Energy, Equilibrium, Experimental, FTIR, Gibbs Free Energy, Intraparticle Diffusion, Intraparticle Diffusion Model, Isotherm, Isotherm Model, Isotherms, Kinetics, Langmuir, Langmuir Isotherm, Langmuir Isotherm Model, Methylene-Blue Dye, Model, Modification, Modified, Montmorillonite, Organoclay, pH, Pseudo Second Order, Pseudo-Second-Order, Pseudo-Second-Order Rate, Reactive Dye, Removal, Rights, Solutions, Sorption, Surface, Surface Modification, Surfactant, Temperature, Textile Dye, Thermodynamic, Utilization, Waste-Water

? Lima, E.C., Royer, B., Vaghetti, J.C.P., Brasil, J.L., Simon, N.M., dos Santos, Jr., A.A., Pavan, F.A., Dias, S.L.P., Benvenutti, E.V. and da Silva, E.A. (2007), Adsorption of Cu(II) on Araucaria angustifolia wastes: Determination of the optimal conditions by statistic design of experiments. Journal of Hazardous Materials, 140 (1-2), 211-220.

Full Text: 2007\J Haz Mat140, 211.pdf

Abstract: Wastes of Araucaria angustifolia (named pinhão) natural (PW) and also loaded with Congo red (CRP) were tested as low-cost adsorbents for Cu(II) removal from aqueous solutions. In order to reduce the total number of experiments to achieve the best conditions of the batch adsorption procedure, three sets of statistical designs of experiments were carried-out for each adsorbent. Initially, a full 24 factorial design for each adsorbent with two central points (18 experiments) were performed, to optimize the following factors: mass of adsorbent (m), pH, time of contact (t) and initial metallic ion concentration (Co). These results indicated that almost all the main factors and its interactions were significant. It was verified for both adsorbents, that a mass of 30.0 mg leaded to higher Cu(II) uptake and that the best pH for Cu(II) adsorption was 5.6. In order to continue the batch adsorption optimization of the systems, a central composite surface analysis design with two factors (Co, t) containing 13 experiments, divided in 4 cube points, 4 axial points and 5 centre points was carried-out for each adsorbent. By performing these two sets of statistical design of experiments, the best conditions for Cu(II) uptake using pinhão wastes (PW) and pinhão wastes loaded with Congo red (CRP) using batch adsorption system, where: m= 30.0 mg of adsorbent; pH=5.6; t= 2.5 h. After optimizing the batch adsorption system by statistical design of experiments, isotherms for Cu(II) uptake using PW and CRP were performed. These isotherms fitted to the linear Langmuir and Freundlich models.

Keywords: Adsorbent, Adsorbents, Adsorption, Analysis, Aqueous-Solutions, Araucaria Angustifolia, Batch Adsorption Procedure, Batch Conditions, Biosorption, Biosorption, Composite, Concentration, Congo Red, Copper(II), Design, Factorial Design, Freundlich, Heavy-Metals, Interactions, Ion, Isotherms, Langmuir, Low-Cost Adsorbents, Models, Natural, Optimization, pH, Pinhao Wastes Loaded With Congo Red, Removal, Sorption, Statistical Design of Experiments, Surface, Surface Analysis, T, Uptake, Wastes, Water, Wheat Bran

? Pehlivan, E. and Altun, T. (2007), Ion-exchange of Pb²⁺, Cu²⁺, Zn²⁺, Cd²⁺, and Ni²⁺ ions from aqueous solution by Lewatit CNP 80. Journal of Hazardous Materials, 140 (1-2), 299-307.

Full Text: 2007\J Haz Mat140, 299.pdf

Keywords: AAS, Acid Chelating Resin, Adsorption, Capacity, Chromium, Concentration, Concentrations, Copper, Cu²⁺, Distribution, Distribution Coefficient, Equilibrium, Heavy Metal Ions, Heavy Metals, Heavy-Metal Ions, Investigations, Ion, Ion Exchange, Ion-Exchange, Ionic Strength, Isotherm, Kinetics, Langmuir, Langmuir Isotherm, Metal, Metal Ions, Metal Removal, Metals, Methods, Nickel, Performance, pH, Preconcentration, Range, Removal, Resins, Selective, Sorbed, Sorption, Sorption Kinetics, TP, Uptake, Waste-Water, Zn²⁺

? Covelo, E.F., Vega, F.A. and Andrade, M.L. (2007), Competitive sorption and desorption of heavy metals by individual soil components. Journal of Hazardous Materials, 140 (1-2), 308-315.

Full Text: 2007\J Haz Mat140, 308.pdf

Abstract: Knowledge of sorption and desorption of heavy metals by individual soil components should be useful for modelling the behaviour of soils of arbitrary composition when contaminated by heavy metals, and for designing amendments increasing the fixation of heavy metals by soils polluted by these species. In this study the competitive sorption and desorption of Cd, Cr, Cu, Ni, Pb and Zn by humified organic matter, Fe and Mn oxides, kaolinite, vermiculite and mica were investigated. Due to the homogeneity of the sorbents, between-metal competition for binding sites led to their preferences for one or another metal being much more manifest than in the case of whole soils. On the basis of k(d100) values (distribution coefficients calculated in sorption-desorption experiments in which the initial sorption solution contained 100 mg L-1 of each metal), kaolinite and mica preferentially sorbed and retained chromium; vermiculite, copper and zinc; HOM, Fe oxide and Mn oxide, lead (HOM and Mn oxide also sorbed and retained considerable amounts of copper). Mica only retained sorbed chromium, Fe oxide sorbed cadmium and lead, and kaolinite did not retain sorbed copper. The sorbents retaining the greatest proportions of sorbed metals were vermiculite and Mn oxide, but the ratios of kd(100) values for retention and sorption suggest that cations were least reversibly bound by Mn oxide, and most reversibly by vermiculite. (c) 2006 Elsevier B.V. All rights reserved.

Keywords: Adsorption, Binding, Cadmium, Cd, Chromium, Clay, Competition, Composition, Copper, Cu, Desorption, Distribution, Distribution Coefficient, Heavy Metals, Humic Umbrisols, Iron-Oxide, Kaolinite, Lead, Manganese-Oxide, Matter, Metal, Metals, Modelling, Organic, Organic Matter, Organic-Matter, Oxides, Pb, Removal, Retention, Selectivity Sequence, Sites, Soil, Soils, Sorbed, Sorption, Titration, Trace-Metals, Zinc

? Mozia, S., Toyoda, M., Inagaki, M., Tryba, B. and Morawski, A.W. (2007), Application of carbon-coated TiO₂ for decomposition of methylene blue in a photocatalytic membrane reactor. Journal of Hazardous Materials,