Personal Research Database

Full Text: 2010\J Haz Mat178, 1146.pdf

Keywords: Adsorption, Industrial Wastewater, Removal, Skin, Wastewater

? Li, P., Su, Y.J., Wang, Y., Liu, B. and Sun, L.M. (2010), Bioadsorption of methyl violet from aqueous solution onto Pu-erh tea powder. Journal of Hazardous Materials, 179 (1-3), 43-48.

Full Text: 2010\J Haz Mat179, 43.pdf

Abstract: Chinese unique Pu-erh tea powder (PTP), with leached active ingredients, was used here to adsorb methyl violet (MV), a cationic dye. The effects of several variables on the removal of methyl violet were studied at 25°C, including pH value, contact time, quantity of the adsorbent, initial concentration, and particle size of the adsorbent. The results showed that the particle size of the adsorbent significantly affected the adsorption process, and the nano-sized PTP particles had the best adsorption efficiency. The equilibrium data was analyzed using Langmuir. Freundlich, and Tempkin isotherms models. The pseudo-second-order kinetics model best explained the MV adsorption by PTP of any particle size. The intra-particle diffusion model was also used to analyze the adsorption process, and it was found that smaller adsorbent particles had a bigger boundary layer effect. (C) 2010 Elsevier B.V. All rights reserved.

Keywords: Adsorbent, Adsorption, Adsorptive Removal, Bagasse-Fly-Ash, Bioadsorption, Blue, Crystal Violet, Diffusion, Dye, Dyes, Equilibrium, Isotherms, Kinetics, Langmuir, Leaf Powder, Methyl Violet, Pu-erh Tea Powder, Sorption, Waste-Water, Wood Sawdust

? Šojić, D.V., Despotović, V.N., Abazović, N.D., Ćomor, M.I. and Abramović, B.F. (2010), Photocatalytic degradation of selected herbicides in aqueous suspensions of doped titania under visible light irradiation. Journal of Hazardous Materials, 179 (1-3), 49-56.

Full Text: 2010\J Haz Mat179, 49.pdf

Abstract: The aim of this work was to study the efficiency of Fe- and N-doped titania suspensions in the photocatalytic degradation of the herbicides RS-2-(4-chloro-o-tolyloxy)propionic acid (mecoprop, MCPP), (4-chloro-2-methylphenoxy)acetic acid (MCPA), and 3,6-dichloropyridine-2-carboxylic acid (clopyralid, CP) under the visible light (lambda >= 400 nm) irradiation. The obtained results were compared with those of the corresponding undoped TiO₂ (rutile/anatase) and of the most frequently used TiO₂ Degussa P25. Computational modeling procedures were used to optimize geometry and molecular electrostatic potentials of MCPP, MCPA and CP and discuss the obtained results. The results indicate that the efficiency of photocatalytic degradation is greatly influenced by the molecular structure of the compound. Lowering of the band gap of titanium dioxide by doping is not always favorable for increasing photocatalytic efficiency of degradation. (C) 2010 Elsevier B.V. All rights reserved.

Keywords: Adsorption, Degradation, Electrodes, Fe-Doped Rutile TiO₂, Herbicides, MCPA, Mecoprop, MEP Study, Modeling, N-Doped Anatase TiO₂, Nitrogen, Particles, Pesticides, Photodegradation, Powders, Reduction, TiO₂, TiO₂ Suspensions, Visible Light Irradiation, Water

? Nanseu-Njiki, C.P., Dedzo, G.K. and Ngameni, E. (2010), Study of the removal of paraquat from aqueous solution by biosorption onto Ayous (Triplochiton schleroxylon) sawdust. Journal of Hazardous Materials, 179 (1-3), 63-71.

Full Text: 2010\J Haz Mat179, 63.pdf

Abstract: This study concerns the batch biosorption of paraquat on Ayous (Triplochiton schleroxylon) sawdust; the study centers on the evolution of biosorption parameters during the process. It appears that paraquat forms a monolayer on the sawdust surface as evidenced by the good correlation between the experimental data and the Langmuir model. The biosorption which is rather fast (the equilibrium was reached after ten minutes) follows a pseudo-second-order kinetic model and does not obey to the intra-particle diffusion model. According to the mathematical kinetic modeling, pore and surface mass transfer well describe the phenomenon. NaCl reduces the adsorption capacity of the material but has no significant effect on the kinetics. Alkaline solutions enhance the accumulation of the pollutant, the reverse being observed for acidic media. According to the thermodynamic data, this biosorption is a spontaneous and exothermic process. From these results we concluded that the adsorption of the pollutant is mainly due to cation exchange as indicated by the adsorption energy determined by the Dubinin-Radushkevich model (E = 12.0736 kJ mol^-1); some other interactions resulting from the affinity through organophilic interactions between paraquat and sawdust have also been pointed out. Desorption experiments conducted in HCl and HNO₃ solutions confirmed the proposed mechanism. (C) 2010 Elsevier B.V. All rights reserved.

Keywords: Activated Clay, Adsorption, Ayous, Biosorption, Cation Exchange, Copper, Desorption, Diffusion, Dyes, Equilibrium, Heavy-Metal Ions, Herbicide Paraquat, Kinetic, Kinetics, Langmuir, Methyl Parathion Pesticide, Paraquat, Sawdust, Sorption, Waste-Water, Wood Sawdust

? Estrellan, C.R., Salim, C. and Hinode, H. (2010), Photocatalytic decomposition of perfluorooctanoic acid by iron and niobium co-doped titanium dioxide. Journal of Hazardous Materials, 179 (1-3), 79-83.

Full Text: 2010\J Haz Mat179, 79.pdf

Abstract: The photocatalytic decomposition of perfluorooctanoic acid (PFOA) in aqueous solution using Fe and Nb co-doped TiO2 (Fe:Nb-TiO2) prepared by sol-gel method was investigated. The photocatalytic activity of Fe:Nb-TiO2 towards PFOA degradation was compared to that of pure TiO2 synthesized using the same method, and that of the commercially available TiO2 photocatalyst, Aeroxide TiO2 P25 (AO-TiO2 P25). The photocatalysts were characterized by XRD, DRS, BET-N-2 adsorption isotherm, and SEM-EDX techniques and the data were correlated to the photocatalytic activity. Fe:Nb-TiO2 showed the highest activity compared to the undoped TiO2 and the commercially available TiO2. Such activity was attributable to the effects of co-doping both on the physico-chemical properties and surface interfacial charge transfer mechanisms. Perfluorocarboxylic acids (PFCAs) with shorter carbon chain length and fluoride ions were identified as photocatalytic reaction intermediates and products. (C) 2010 Elsevier B.V. All rights reserved.

Keywords: Adsorption, Adsorption Isotherm, Degradation, Fluoride, Isotherm, Metal Co-Doping, Oxidation, Perfluorocarboxylic Acids, PFOA, Sol-Gel, TiO₂, TiO₂ Photocatalysis, Valence Band Hole Reaction, Visible-Light, XRD

? Tang, Q.A., Tang, X.W., Hu, M.M., Li, Z.Z., Chen, Y.M. and Lou, P. (2010), Removal of Cd(II) from aqueous solution with activated Firmiana Simplex Leaf: Behaviors and affecting factors. Journal of Hazardous Materials, 179 (1-3), 95-103.

Full Text: 2010\J Haz Mat179, 95.pdf

Abstract: Cadmium pollution is known to cause severe public health problems. This study is intended to examine the effect of an activated Firmiana Simplex Leaf (FSL) on the removal of Cd(II) from aqueous solution. Results showed that the active Firmiana Simplex Leaf could efficiently remove Cd(II) from wastewater due to the preservation of beneficial groups (amine, carboxyl, and phosphate) at a temperature of 250 degrees C. The adsorbent component, dosage, concentration of the initial solute, and the pH of the solution were all found to have significant effects on Cd(II) adsorption. The kinetic constants were predicted by pseudo-first-order kinetics, and the thermodynamic analysis revealed the endothermic and spontaneous nature of the adsorption. FT-IR and XRD analyses confirmed the strong adsorption between beneficial groups and cadmium ions, and the adsorption capacity was calculated to be 117.786 mg g(-1) according to the Langmuir isotherm. (C) 2010 Elsevier B.V. All rights reserved.

Keywords: Adsorption, Adsorption, Adsorption Capacity, Amine, Analysis, Biosorption, Black Gram Husk, Cadmium, Carbon, Carboxyl, Cd(II), Chinese Loess, Equilibrium, Firmiana Simplex Leaf, FTIR, Heavy-Metals, Isotherm, Kinetic, Kinetics, Langmuir, Langmuir Isotherm, Pb(II), pH, Phosphate, Pollution, Removal, Thermodynamic, Thermodynamic Parameters, Waste-Water, Wastewater, Xrd

? Shen, S.B., Pan, T.L., Liu, X.Q., Yuan, L., Wang, J.C., Zhang, Y.J. and Guo, Z.C. (2010), Adsorption of Rh(III) complexes from chloride solutions obtained by leaching chlorinated spent automotive catalysts on ion-exchange resin Diaion WA21J. Journal of Hazardous Materials, 179 (1-3), 104-112.

Full Text: 2010\J Haz Mat179, 104.pdf

Abstract: It was found that Rh, Pd and Pt contained in the spent ceramic automotive catalysts could be effectively extracted by dry chlorination with chlorine. In order to concentrate Rh(III) ions contained in the chloride solutions obtained, thermodynamic and kinetics studies for adsorption of Rh(III) complexes from the chloride solutions on an anionic exchange resin Diaion WA21J were carried out. Rh, Pd, Pt, Al, Fe, Si, Zn and Pb from the chloride solution could be adsorbed on the resin. The distribution coefficients (K-d) of Rh(III) decreased with the increase in initial Rh(III) concentration or in adsorption temperature. The isothermal adsorption of Rh(III) was found to fit Langmuir, Freundlich and Dubinin-Kaganer-Radushkevich models under the adsorption conditions. The maximum monolayer adsorption capacities Q(max) based on Langmuir adsorption isotherms were 6.39, 6.61 and 5.81 mg/g for temperatures 18, 28 and 40 degrees C, respectively. The apparent adsorption energy of Rh was about -7.6 kJ/mol and thus Rh(III) adsorption was a physical type. The experimental data obtained could be better simulated by pseudo-first-order kinetic model and the activation energy obtained was 6.54 J/mol. The adsorption rate of Rh(III) was controlled by intraparticle diffusion in most of time of adsorption process. (C) 2010 Elsevier B.V. All rights reserved.

Keywords: Adsorption, Adsorption Isotherms, Chloride Solution, Converters, Diaion WA21J, Diffusion, Extraction, Freundlich, Ion Exchange, Ion-Exchange Resin, Isotherms, Kinetic, Kinetic Model, Kinetics, Langmuir, Palladium, Platinum-Group Metals, Recovery, Removal, Rh(III), Separation, Sorption, Surfactant-Modified Montmorillonite, Thermodynamic

? Shao, Y., Xu, Z.Y., Wan, H.Q., Chen, H.A., Liu, F.L., Li, L.Y. and Zheng, S.R. (2010), Influence of ZrO₂ properties on catalytic hydrodechlorination of chlorobenzene over Pd/ZrO₂ catalysts. Journal of Hazardous Materials, 179 (1-3), 135-140.

Full Text: 2010\J Haz Mat179, 135.pdf

Abstract: Pd/ZrO₂ catalysts using different ZrO₂ as supports were prepared using the deposition-precipitation method and were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy. N-2 adsorption, temperature programmed reduction, H-2 chemisorption and measurement of surface hydroxyl group. Catalytic hydrodechlorination (HOC) of chlorobenzene was used to evaluate the activity and stability of the catalyst. The results showed that ZrO₂ support calcined at 300 degrees C was amorphous in nature, whereas ZrO₂ supports calcined at 500 and 600 degrees C consisted of both monoclinic and tetragonal phases. In addition, increasing calcination temperature led to the decrease of specific surface area and surface hydroxyl group content of the ZrO₂ support. For temperature programmed reduction of PdO/ZrO₂ samples, two H-2 consumption peaks with varied reduction temperature were distinctly observed, implying the existence of different Pd species in Pd/ZrO₂ catalysts. In addition, Pd/ZrO₂ catalyst with ZrO₂ calcined at 500 degrees C had a relatively higher content of Pd species with strong metal-support interaction than other catalysts. For catalytic HDC of chlorobenzene, Pd/ZrO₂ catalyst with ZrO₂ support calcined at 500 degrees C exhibited a higher initial activity and stability as compared to other catalysts, indicative of a strong dependence of the catalytic behavior of the Pd/ZrO₂ catalyst on the support properties for catalytic HOC of chlorobenzene. (C) 2010 Elsevier B.V. All rights reserved.

Keywords: Adsorption, Carbon, Catalytic Hydrodechlorination, CCL2F2 CFC-12, CH2F2 HFC-32, Chlorobenzene, Deactivation, H-2, Liquid-Phase Hydrodechlorination, Palladium-Supported Catalysts, Pd Catalysts, Pd, Al2O3 Catalysts, Pd, ZrO₂ Catalyst, Selective Hydrogenolysis, Temperature, X-Ray Diffraction, X-Ray Photoelectron Spectroscopy, ZrO₂, ZrO₂ Support

? Ai, Z.H., Lee, S.C., Huang, Y., Ho, W.K. and Zhang, L.Z. (2010), Photocatalytic removal of NO and HCHO over nanocrystalline Zn₂SnO₄ microcubes for indoor air purification. Journal of Hazardous Materials, 179 (1-3), 141-150.

Full Text: 2010\J Haz Mat179, 141.pdf

Abstract: Nanocrystalline Zn2SnO4 microcubes were hydrothermally synthesized and systematically characterized by XRD, SEM, TEM, XPS, N-2 adsorption-desorption, and UV-vis DRS analysis. The resulting Zn2SnO4 microcubes with the edge size ranging from 0.8 to 1.2 mu m were composed of numerous nanoparticles with size of 10-20 nm, and their optical band gap energy was estimated to be 3.25 eV from the UV-vis diffuse reflectance spectra. On degradation of nitrogen monoxide (NO) and formaldehyde (HCHO) at typical concentrations for indoor air quality, these nanocrystalline Zn2SnO4 microcubes exhibited superior photocatalytic activity to the hydrotherrnally synthesized ZnO, SnO2, and Degussa TiO2 P25, as well as C doped TiO2 under UV-vis light irradiation. This enhanced photocatalytic activity of the nanocrystalline Zn2SnO4 microcubes was attributed to their bigger surface areas, smaller particle size, special porous structures, and special electronic configuration. The nanocrystalline Zn2SnO4 microcubes were chemically stable as there was no obvious deactivation during the multiple photocatalytic reactions. This work presents a promising approach for scaling-up industrial production of Zn2SnO4 nanostructures and suggests that the synthesized nanocrystalline Zn2SnO4 microcubes are promising photocatalysts for indoor air purification. (C) 2010 Elsevier B.V. All rights reserved.

Keywords: Analysis, Degradation, Hcho, Hydrothermal Synthesis, Modified Titanium-Dioxide, Nanoparticles, Nanostructures, NO, Oxidation, Phase, Photocatalysis, Photodegradation, Pollutants, Production, Removal, Removal of NO, SEM, TEM, TiO₂, Visible-Light, XPS, XRD, Zn₂SnO₄

? Li, H.F., Lin, Y.B., Guan, W.M., Chang, J.L., Xu, L., Guo, J.K. and Wei, G.H. (2010), Biosorption of Zn(II) by live and dead cells of Streptomyces ciscaucasicus Strain CCNWHX 72-14. Journal of Hazardous Materials, 179 (1-3), 151-159.

Full Text: 2010\J Haz Mat179, 151.pdf

Abstract: The biosorption characteristics of Zn(II) using live and dead cells of Streptomyces ciscaucasicus strain CCNWHX 72-14 as biosorbents have been investigated in the present research. Optimum conditions for biosorption were determined to be: pH adjusted to 5.0, agitated at 90 rpm and at a dose of 2 g/L. For initial zinc concentrations of 1-150 mg/L, batch biosorption data of live biomass preferred to be simulated with Freundlich model while those of dead strain fit Langmuir isotherm well. Experimental maximum biosorption capacity turned out to be 42.75 mg/g (0.654 mmol/g) for living material and 54 mg/g (0.826 mmol/g) for dead sorbents, respectively. The pseudo-second-order equation, instead of the pseudo-first-order one, was chosen to describe the time course biosorption process. In contrast to live biosorbents, dead biomass seemed to have lower binding strength with higher desorption efficiency at pH 1.0. Competitive biosorption revealed the order of competing metal ion to be: Cu²⁺ > Cd²⁺ > Ni⁺. FT-IR analysis indicated that more functional groups were involved in the biosorption process of dead adsorbents, compared with those linked to live biomass. Taken together, it can be concluded that dead cells of CCNWHX 72-14 were better and cheaper biosorbents than live ones. (C) 2010 Elsevier B.V. All rights reserved.

Keywords: Activated Carbon, Adsorption, Agricultural Waste, Aqueous-Solution, Biosorption, Dead, Equilibrium, Heavy-Metals, Isotherm, Langmuir, Langmuir Isotherm, Live, Metal Biosorption, Removal, Research, Rimosus Biomass, Streptomyces, Zinc, Zinc

? Shen, Y.S., Wang, S.L., Huang, S.T., Tzou, Y.M. and Huang, J.H. (2010), Biosorption of Cr(VI) by coconut coir: Spectroscopic investigation on the reaction mechanism of Cr(VI) with lignocellulosic material. Journal of Hazardous Materials, 179 (1-3), 160-165.

Full Text: 2010\J Haz Mat179, 160.pdf

Abstract: In this study, the removal mechanism of Cr(VI) from water by coconut coir (CC) was investigated using Xray photoelectron spectroscopy (XPS), Cr K-edge X-ray absorption near edge structure (XANES) and FTIR spectroscopy. The results showed that, upon reaction with CC at pH 3, Cr(VI) was reduced to Cr(III), which was either bound to CC or released back into solution. As revealed by the FTIR spectra of CC before and after reacting with Cr(VI), the phenolic methoxyl and hydroxyl groups of lignin in CC are the dominant drivers of Cr(VI) reduction, giving rise to carbonyl and carboxyl groups on CC. These functional groups can subsequently provide binding sites for Cr(III) resulting from Cr(VI) reduction. In conjunction with forming complexes with carbonyl and carboxyl groups, the formation of Cr(III) hydroxide precipitate could also readily occur as revealed by the linear combination fitting of the Cr K-edge XANES spectrum using a set of reference compounds. The phenolic groups in lignin are responsible for initiating Cr(VI) reduction, so lignocellulosic materials containing a higher amount of phenolic groups are expected to be more effective scavengers for removal of Cr(VI) from the environment. (C) 2010 Elsevier B.V. All rights reserved.

Keywords: 2p Photoelectron-Spectra, Agricultural Waste, Aqueous-Solutions, Biosorption, Compounds, Cr(VI), FTIR, Heavy-Metals, Hexavalent Chromium, Hexavalent Chromium, Lignocellulose, Low-Cost Adsorbents, Near-Edge Structure, pH, Reaction Mechanism, Reduction, Removal, Sorption, Surface Precipitation, Trivalent Chromium, Waste-Water, Water, X-Ray-Absorption, XPS

? Labanowski, J., Pallier, V. and Feuillade-Cathalifaud, G. (2010), Study of organic matter during coagulation and electrocoagulation processes: Application to a stabilized landfill leachate. Journal of Hazardous Materials, 179 (1-3), 166-172.

Full Text: 2010\J Haz Mat179, 166.pdf

Abstract: Organic matter contained in leachates appears to be a relevant indicator of waste evolution. Among the physico-chemical treatments applied to stabilize leachates, coagulation-flocculation is considered a classical process and electrocoagulation can be developed. Electrocoagulation tests were carried out in a laboratory pilot using aluminium plates and compared to classical coagulation-floculation with aluminium ions and to electrolysis alone. The leachate used in this study came from the landfill of Crezin (Limoges, France) and it presented low biodegradability and high concentration of macromolecules. To assess the efficiency of the chemical and electrochemical processes, we specifically studied Organic Matter (OM) by using two protocols: adsorption on XAD resins and fractionation by ultrafiltration. Biodegradable Dissolved Organic Carbon (BDOC) measurements were applied to the fractions extracted by XAD resins and were also used as an indicator of the efficiency of the treatments. Residual organic matter concentration was the same for the two processes but its composition appeared different after electrocoagulation: a higher percentage of small hydrophilic organic molecules which seemed to be less biodegradable than the initial organic matter was observed. (C) 2010 Elsevier B.V. All rights reserved.

Keywords: Adsorption, Aluminium, Aquatic Humic Substances, Biodegradable Fraction, Biodegradation, Carbon, Coagulation, Degradation, Electrocoagulation, Electrolysis, Fractionation, Impact, Leachate, Molecules, Organic Matter, Oxidation, Removal, Ultrafiltration, Waste-Water, Water-Treatment

? Santhi, T., Manonmani, S. and Smitha, T. (2010), Removal of malachite green from aqueous solution by activated carbon prepared from the epicarp of Ricinus communis by adsorption. Journal of Hazardous Materials, 179 (1-3), 178-186.

Full Text: 2010\J Haz Mat179, 178.pdf

Abstract: The use of low-cost, locally available, highly efficient and eco-friendly adsorbents has been investigated as an ideal alternative to the current expensive methods of removing dyes from wastewater. This study investigates the potential use of activated carbon prepared from the epicarp of Ricinus communis for the removal of malachite green (MG) dye from simulated wastewater. The effects of different system variables, adsorbent dosage, initial dye concentration, pH and contact time were investigated and optimal experimental conditions were ascertained. The results showed that as the amount of the adsorbent increased, the percentage of dye removal increased accordingly. Optimum pH value for dye adsorption was 7.0. Maximum dye was sequestered within 50 min of the start of every experiment. The adsorption of malachite green followed the pseudo-second-order rate equation and fits the Langmuir, Freundlich, Dubinin-Radushkevich (D-R) and Tempkin equations well. The maximum removal of MG was obtained at pH 7 as 99.04% for adsorbent dose of 1 g 50 mL^-1 and 25 mg L^-1 initial dye concentration at room temperature. Activated carbon developed from R. communis can be an attractive option for dye removal from diluted industrial effluents since test reaction made on simulated dyeing wastewater showed better removal percentage of MG. (C) 2010 Elsevier B.V. All rights reserved.

Keywords: Activated Carbon, Adsorbent, Adsorption, Basic-Dyes, Biosorption, Dye, Epicarp, Equilibrium, Kinetic-Model, Langmuir, Low-Cost Adsorbents, Malachite Green, Methylene-Blue, Model Parameters, Nonlinear Methods, Removal, Ricinus Communis, Sorption Isotherms, Tree Fern, Wastewater

? Zimmermann, A.C., Mecabô, A., Fagundes, T. and Rodrigues, C.A. (2010), Adsorption of Cr(VI) using Fe-crosslinked chitosan complex (Ch-Fe). Journal of Hazardous Materials, 179 (1-3), 192-196.

Full Text: 2010\J Haz Mat179, 192.pdf

Abstract: In the present investigation. Fe-chitosan crosslinked is used as adsorbent for the removal of chromium from aqueous solutions. The influence of pH, temperature and other ions was evaluated. pH 2.0 was found to be the optimum pH for adsorption of Cr(VI)onto Ch-Fe. Coordination of unsaturated sites for the iron(III) complex of polymer were considered to be the adsorption sites for Cr(VI) species, the predominant species being HCrO(4)(-). The Langmuir and Langmuir-Freundlich adsorption isotherm models were applied to describe the isotherm parameter for Cr(VI) adsorption. The results indicate that the Langmuir-Freundlich adsorption model and maximum adsorption capacity was calculated as 295 mg/g at 25 degrees C, with pH 4.7. Cr(VI) uptake on the adsorbent decreased from 295 mg/g at 25ºC to 209 mg/g at 65ºC. Rate constants as a function of temperature were evaluated with the help of a proposed second order kinetic model. The other coexisting ions, nitrate, chlorides and sulphate influenced Cr(VI) adsorption. (c) 2010 Elsevier B.V. All rights reserved.

Keywords: Adsorbent, Adsorption, Adsorption Isotherm, Aqueous-Solution, Capacity, Chitosan, Chitosan-Iron, Chromium, Chromium(VI), Cr(VI), Equilibrium, Hexavalent Chromium, Ion-Exchange, Ions, Iron, Isotherm, Isotherm Models, Kinetic, Kinetic Model, Kinetics, Model, Nitrate, pH, Removal, Speciation, Thermodynamics, Uptake, Waste-Water

? Zhang, Y., Dou, X.M., Yang, M., He, H., Jing, C.Y. and Wu, Z.Y. (2010), Removal of arsenate from water by using an Fe-Ce oxide adsorbent: Effects of coexistent fluoride and phosphate. Journal of Hazardous Materials,