Personal Research Database

Full Text: 2009\J Haz Mat172, 650.pdf

Abstract: Bis-2-chloroethyl sulphide (sulphur mustard or HD) is an extremely toxic and persistent chemical warfare agent. For in-situ degradation of HD and its analogues (simulants), i.e., dibutyl sulphide (DBS) and ethyl 2-hydroxyethyl sulphide (HEES), different adsorbents systems loaded with (1R)-(-)-(camphorylsulphonyl) oxaziridine were prepared. Solution of sulphur mustard and its simulants was prepared in carbon tetrachloride and taken for uniform adsorption on the impregnated systems using incipient volume. Degradation kinetics monitored by GC, FID were found to be first-order. The half-life of degradation reactions for simulants was obtained in less than 30 and for HD in 120 min. From the studied kinetics it was observed that reaction was very rapid with simulants and decreased rate was found for HD. The order of reactivity of MgO, Oxa system for HD and simulants was found to be DBS > HEES > HD. Reaction products of the oxidation reaction of simulants and HD on adsorbents were extracted in dichloromethane and analysed by CC-MS. The products were found to be non-toxic sulphoxide. The objective of the study is to develop a reactive adsorbent for in-situ degradation of sulphur mustard which could be used in nuclear biological and chemical (NBC) filtration systems. (C) 2009 Elsevier B.V. All rights reserved.

Keywords: (1R)-(-)-(Camphorylsulphonyl) Oxaziridine, 2-Chloroethyl Sulfides, Absorption, Adsorbent, Adsorption, Decontamination, Degradation, Degradation Products, First Order, GD, HD, Hydrolysis, Kinetics, Mechanism, Oxidation, Oxygen-Transfer, Sulfoxides, Sulphur Mustard, VX

? Aytas, S., Yurtlu, M. and Donat, R. (2009), Adsorption characteristic of U(VI) ion onto thermally activated bentonite. Journal of Hazardous Materials, 172 (2-3), 667-674.

Full Text: 2009\J Haz Mat172, 667.pdf

Abstract: In this study, the effect of pH, contact time, temperature, and initial metal concentration on U(VI) adsorption on thermally activated bentonite (TAB) was investigated. Graphical correlation of various adsorption isotherm models like, Freundlich, and Dubinin-Radushkevich have been carried out for TAB. Various thermodynamic parameters, such as, Gibb’s free energy, entropy and enthalpy of the on-going adsorption process have been calculated. In order to reveal the adsorptive characteristic of bentonite samples, surface area, FT-IR, and DTA-TG spectra analyses were carried out. The results show that TAB samples can be an alternative low cost adsorbent for removing U(VI) ions from aqueous solutions. (C) 2009 Elsevier B.V. All rights reserved.

Keywords: Acid Activation, Adsorption, Adsorption Isotherm, Aqueous, Bentonite, Calcination, Clay, Elsevier, FT-IR, FTIR, Heavy-Metals, Isotherm, Mechanisms, Metal, Minerals, Models, Montmorillonite, Removal, Smectite, Solutions, Sorption, Surface Area, Temperature, Thermal Treatment, Thermodynamic, Thermodynamic Parameters, Uranium, Uranium

? Islam, M. and Patel, R. (2009), Removal of lead(II) from aqueous environment by a fibrous ion exchanger: Polycinnamamide thorium(IV) phosphate. Journal of Hazardous Materials, 172 (2-3), 707-715.

Full Text: 2009\J Haz Mat172, 707.pdf

Abstract: The objective of the present research was to synthesize. characterize and to investigate the removal efficiency of lead(II) ion from synthetic lead solution by a hybrid fibrous ion exchanger. In the present study polycinnamamide thorium(IV) phosphate was synthesized by co-precipitation method and was characterized using SEM, XRD, MR and TGA-DSC. To know the practical applicability, a detailed removal study of lead ion was carried out using the material. The removal of lead was 81.2% under optimum conditions. Adsorption kinetic study revealed that the adsorption process followed first order kinetics. Adsorption data were fitted to linearly transformed Langmuir isotherm with R(2) (correlation coefficient) >0.99. Thermodynamic parameters were also calculated to study the effect of temperature on the removal process. In order to understand the adsorption type, equilibrium data were tested with Dubinin-Radushkevich isotherm. (C) 2009 Elsevier B.V. All rights reserved.

Keywords: Adsorption, Adsorption Kinetic, Bagasse, Cadmium, Co-Precipitation, Coprecipitation, Crystalline, DR Isotherm, Earth-Elements, Environment, Equilibrium, First Order, Fluoride, Fly-Ash, Isotherm, Kinetic, Kinetics, Lagergren Rate Equation, Langmuir Isotherm, Lead, Metal-Ions, Phosphate, Removal, Research, SEM, Thermodynamic, Thermodynamic Parameter, Thermodynamic Parameters, Waste-Water, XRD

? Biswas, B.K., Inoue, J., Kawakita, H., Ohto, K. and Inoue, K. (2009), Effective removal and recovery of antimony using metal-loaded saponified orange waste. Journal of Hazardous Materials, 172 (2-3), 721-728.

Full Text: 2009\J Haz Mat172, 721.pdf

Abstract: Zr(IV) and Fe(III) ions were loaded onto an orange waste precursor to prepare a metal-loaded orange waste gel, which was investigated for the adsorptive removal and recovery of antimony (III and V) from an aqueous environment. The loading capacity of the orange waste for Zr(IV) and Fe(III) was found to be 1.40 and 1.87 mmol/g, respectively. The maximum batch mode sorption capacity of the Zr(III)-loaded saponified orange waste (SOW) gel was found to be 0.94 mmol/g for Sb(III) and 1.19 mmol/g for Sb(V). A nearly similar result was found for the Fe(Ill)-loaded SOW gel with the sorption capacity for Sb(III) and Sb(V) being 1.12 and 1.19 mmol/g, respectively. The presence of a variety of anionic species such as carbonate, chloride, nitrate and sulfate had no influence on the adsorption of both Sb(III) and Sb(V). A column adsorption-elution test demonstrated the utility of this system in continuous mode. Selective sulfide precipitation of antimony is one of the major findings in the present work. which clearly suggests a means of effective recovery of antimony from solution containing antimony and other metal ions. Due to their low cost, availability and significantly high adsorption capacity, the metal-loaded gels are expected to be effectively employed for the removal and recovery of antimony from aqueous solution, thus leading to the establishment of a greener environment. (C) 2009 Elsevier B.V. All rights reserved.

Keywords: Activated Carbon, Adsorption, Adsorption, Adsorption Capacity, Antimony, Aqueous, Capacity, Elsevier, Elution, Environment, Graphite, Hydrous Zirconium-Oxide, Ligand Exchange, Metal, Metal Ions, Orange Waste, Preconcentration, Recovery, Removal, Separation, Sorption, Species, Spectrometry, Sulfate, System, Trace-Elements, Water

? Eroglu, H., Yapici, S., Nuhoglu, C. and Varoglu, E. (2009), Biosorption of Ga-67 radionuclides from aqueous solutions onto waste pomace of an olive oil factory. Journal of Hazardous Materials, 172 (2-3), 729-738.

Full Text: 2009\J Haz Mat172, 729.pdf

Abstract: The aim of this research was to test the removal of Ga-67 radionuclides from aqueous solutions by biosorption onto waste pomace of an olive oil factory (WPOOF). Batch adsorption studies were performed in order to investigate the temperature, the initial pH of the solution, the stirring speed, the biosorbent dose. and the nominal particle size of the biosorbent in the experimental work. The most effective parameter was found to be the initial pH. A high biosorption yield of 98 was obtained. The equilibrium values were fitted to the isotherm models. The values of ΔG and ΔH were calculated to be negative. The adsorption kinetics calculations showed that the kinetics of the biosorption process fitted well to the pseudo-second order rate model. (C) 2009 Elsevier B.V. All rights reserved.

Keywords: Activated Carbon, Adsorbent, Adsorption, Adsorption Kinetics, Adsorption-Kinetics, Aqueous Solutions, Batch Adsorption, Biosorbent, Biosorption, Copper Sorption, Equilibrium, Experimental, Gallium-67, Heavy Metal, Ions, Isotherm, Isotherm Models, Isotherms, Kinetics, Leaves, Model, Models, Particle Size, pH, Pseudo Second Order, Pseudo-Second Order, Pseudo-Second-Order, Radioactivity, Radionuclide, Radionuclides, Removal, Research, Rights, Size, Solution, Solutions, Temperature, Waste, Work

? Ma, F., Qu, R.J., Sun, C.M., Wang, C.H., Ji, C.N., Zhang, Y. and Yin, P. (2009), Adsorption behaviors of Hg(II) on chitosan functionalized by amino-terminated hyperbranched polyamidoamine polymers. Journal of Hazardous Materials, 172 (2-3), 792-801.

Full Text: 2009\J Haz Mat172, 792.pdf

Abstract: The adsorption behaviors of Hg(II) on adsorbents, chitosan functionalized by generation 1.0-3.0 of amino-terminated hyperbranched polyamidoamine polymers (denoted as CTS-1.0, CTS-2.0 and CTS-3.0, respectively), were studied. The optimum pH corresponding to the maximum adsorption capacities was found to be 5.0 for the three adsorbents. The experimental equilibrium data of Hg(II) on the three adsorbents were fitted to the Freundlich and the Langmuir models, and it is found that the Langmuir isotherm was the best fitting model to describe the equilibrium adsorption. The kinetics data indicated that the adsorption process of Hg(II) ions on CTS-1.0, CTS-2.0 and CTS-3.0 were governed by the film diffusion and followed pseudo-second-order rate model. Thermodynamic analysis and FTIR analysis revealed that the adsorption behaviors of Hg(II) ions on the three adsorbents could be considered as spontaneous, endothermic and chemical sorption process, resulting in their higher adsorption capacities at higher temperature. (C) 2009 Elsevier B.V. All rights reserved.

Keywords: Adsorbent, Adsorbents, Adsorption, Adsorption Capacities, Amino-Terminated Hyperbranched Polyamidoamine Polymers, Analysis, Chemical, Chemical Modification, Chitosan, Data, Dendrimers, Diffusion, Endothermic, Equilibrium, Experimental, Film Diffusion, Freundlich, FTIR, FTIR Analysis, Functionalized Chitosan, Generation, Heavy-Metals, Hg(II), Hg(II) Ions, Ions, Isotherm, Isothermal, Kinetic, Kinetics, Langmuir, Langmuir Isotherm, Mechanisms, Mercury(II), Model, Models, pH, Polymers, Pseudo Second Order, Pseudo-Second-Order, Pseudo-Second-Order Rate, Rights, Sorption, Sorption Process, Spontaneous, Temperature, Thermodynamic

? Sahu, J.N., Acharya, J. and Meikap, B.C. (2009), Response surface modeling and optimization of chromium(VI) removal from aqueous solution using Tamarind wood activated carbon in batch process. Journal of Hazardous Materials, 172 (2-3), 818-825.

Full Text: 2009\J Haz Mat172, 818.pdf

Abstract: The present paper discusses response surface methodology (RSM) as an efficient approach for predictive model building and optimization of chromium adsorption on developed activated carbon. In this work the application of RSM is presented for optimizing the removal of Cr(VI) ions from aqua solutions using activated carbon as adsorbent. All experiments were performed according to statistical designs in order to develop the predictive regression models used for optimization. The optimization of adsorption of chromium on activated carbon was carried out to ensure a high adsorption efficiency at low adsorbent dose and high initial concentration of Cr(VI). While the goal of adsorption of chromium optimization was to improve adsorption conditions in batch process, i.e., to minimize the adsorbent dose and to increase the initial concentration of Cr(VI). In the adsorption experiments a laboratory developed Tamarind wood activated carbon made of chemical activation (zinc chloride) was used. A 2(4) full factorial central composite design experimental design was employed. Analysis of variance (ANOVA) showed a high coefficient of determination value (R(2) = 0.928) and satisfactory prediction second-order regression model was derived. Maximum chromium removal efficiency was predicted and experimentally validated. The optimum adsorbent dose, temperature, initial concentration of Cr(VI) and initial pH of the Cr(VI) solution were found to be 4.3 g, l, 32 degrees C, 20.15 mg, l and 5.41 respectively. Under optimal value of process parameters, high removal (>89%) was obtained for Cr(VI). (C) 2009 Published by Elsevier B.V.

Keywords: Activated Carbon, Activation, Adsorbent, Adsorption, Adsorption, Biomass, Chemical Activation, Chloride, Chromium, Chromium Removal, Chromium(VI), Cr(III), Cr(VI), Design, Designs, Experimental, Hexavalent Chromium, Ions, Methodology, Model, Modeling, Optimization, Performance, pH, Process Parameters, Reduction, Removal, Response Surface Method, Response Surface Modeling, RSM, Statistical, Waste-Water, Wastewater Treatment, Zinc

? Wawrzkiewicz, M. and Hubicki, Z. (2009), Equilibrium and kinetic studies on the adsorption of acidic dye by the gel anion exchanger. Journal of Hazardous Materials, 172 (2-3), 868-874.

Full Text: 2009\J Haz Mat172, 868.pdf

Abstract: In the present study, the gel anion exchanger Purolite A-850 of -N+(CH₃)₃ functional groups was used in order to remove the acidic dye (Acid Blue 29) from aqueous solutions. Batch experiments were conducted to study the effect of phase contact time (1-180 min), initial concentration of dye (100-500 mg/L), solution pH (1-8), anion exchanger dosage (0.25-1.0 g) as well as temperature (20-40ºC). The contact time necessary to reach equilibrium was 40 min with the exception for the solution of the initial concentration 500 mg/L The amounts of Acid Blue 29 adsorbed at equilibrium using the strongly basic anion exchanger were equal to 9.97, 19.97, 29.96 and 49.90 mg/g for the dye solutions of the initial concentrations 100, 200, 300 and 500 mg/L, respectively. The equilibrium sorption capacity slightly increased when the temperature of dye solution increased from 20 to 40ºC. The experimental data were analyzed by the Langmuir, Freundlich and Temkin models of adsorption. The adsorption isotherm data were fitted well to the Langmuir isotherm and the monolayer adsorption capacity was found to be 83.303 mg/g at 20ºC. The value or R_L was equal to 0.00054 (favourable). The kinetic data obtained at different concentrations were modeled using the pseudo-first order, pseudo-second order and intraparticle diffusion equations. The experimental data were well described by the pseudo-second order kinetic model. (C) 2009 Elsevier B.V. All rights reserved.

Keywords: Acid Blue, Acidic Dye, Activated Carbon, Adsorption, Adsorption Capacity, Adsorption Isotherm, Agricultural Waste, Anion Exchange Resin, Aqueous Solutions, Aqueous-Solutions, Basic Dye, Capacity, Concentration, Contact Time, Data, Diffusion, Dye, Equilibrium, Experimental, Experiments, Freundlich, Functional Groups, Gel, Intraparticle Diffusion, Isotherm, Kinetic, Kinetic Model, Kinetic Studies, Langmuir, Langmuir Isotherm, Malachite Green, Methylene-Blue, Model, Models, Monolayer, Nonlinear-Regression Analysis, pH, Pseudo First Order, Pseudo Second Order, Pseudo-First Order, Pseudo-First-Order, Pseudo-Second Order, Pseudo-Second-Order, Reactive Dyes, Removal, Rights, Solution, Solutions, Sorption, Sorption Capacity, Sorption Kinetics, Temperature, Textile Waste-Water, Value

? Maiti, A., Sharma, H., Basu, J.K. and De, S. (2009), Modeling of arsenic adsorption kinetics of synthetic and contaminated groundwater on natural laterite. Journal of Hazardous Materials, 172 (2-3), 928-934.

Full Text: 2009\J Haz Mat172, 928.pdf

Abstract: A simple shrinking core model is applied to predict the adsorption kinetics of arsenite and arsenate species onto natural laterite (NL) in a stirred tank adsorber. The proposed model is a two-resistance model, in which two unknown parameters, external mass transfer coefficient (K-f) and pore diffusion coefficient (D-e) are estimated by comparing the simulation concentration profile with the experimental data using a nonlinear optimization technique. The model is applied under various operating conditions, e.g., initial arsenic concentration, NL dose, NL particle size, temperature, stirring speed, etc. Estimated values of D-e and K-f are found to be in the range of 2.2-2.610^-11 m²/s and 1.0-1.410^-1 m/s at 305 K for different operating conditions, respectively. D-e and K-f values are found to be increasing with temperature and stirrer speed, respectively. Calculated values of Biot numbers indicate that both external mass transfer and pore diffusion are important during the adsorption. The model is also applied satisfactorily to predict the arsenic adsorption kinetics of arsenic contaminated groundwater-NL system and can be used to scale up. (C) 2009 Elsevier B.V. All rights reserved.

Keywords: Activated Alumina, Adsorption, Adsorption Kinetics, Aqueous-Solution, Arsenate, Arsenic, Arsenic Removal, Arsenite, Bangladesh, Core, Diffusion, Drinking-Water, Elsevier, Equilibrium, Kinetics, Laterite, Mass Transfer, Oxidation, Oxide, Pore Diffusivity Coefficient, Removal, Shrinking Core Model, Sorption, Species, System, Temperature, United-States

? Siddique, M., Farooq, R., Khalid, A., Farooq, A., Mahmood, Q., Farooq, U., Raja, I.A. and Shaukat, S.F. (2009), Thermal-pressure-mediated hydrolysis of Reactive Blue 19 dye. Journal of Hazardous Materials, 172 (2-3), 1007-1012.

Full Text: 2010\J Haz Mat172, 1007.pdf

Abstract: The thermal-pressure-mediated hydrolysis rates and the degradation kinetics of environmentally persistent Reactive Blue (RB) 19 dye were studied. The dye decomposition was studied at 40-120 degrees C, pH 2-10. and atmospheric pressure range of 1-2 atm. The intermediates and end products formed during the degradation were identified using gas chromatography, mass spectrometry and a possible degradation pathway of RB 19 was proposed. The stability of the dye in aqueous solution was influenced by changes in pH. At pH 4, half-life was 2247.5 min at 40 degrees C and it reduced to 339.4 min when the temperature was increased to 120 degrees C. Acidic conditions were more conducive to enhance hydrolysis rate than basic ones as the decomposition was optimum at pH 4. The kinetic studies indicated that the rate of hydrolysis apparently followed first order reaction. A linear relationship was observed between hydrolysis rate of RB 19 dye and increasing temperatures and pressures. Overall, 23% dye decomposition occurred in 120 minutes at pH 4,120 degrees C and pressure of 2 atm. Along with thermal-pressure, a combination of techniques like physico-chemical, biological, enzymatic etc. may be more suitable choice for the effective treatment of RB 19 dye. (C) 2009 Elsevier B.V. All rights reserved.

Keywords: Biosorption, Decolorization, Decomposition, Degradation, Electrodes, First Order, Hydrolysis Kinetics, Kinetic, Kinetics, pH, Pressure, Reactive Blue 19, Spectrometry, Textile Waste-Water, Thermal-Pressure Hydrolysis, Treatment, Wastewater Treatment

? Kumar, M., Tripathi, B.P. and Shahi, V.K. (2009), Crosslinked chitosan/polyvinyl alcohol blend beads for removal and recovery of Cd(II) from wastewater. Journal of Hazardous Materials, 172 (2-3), 1041-1048.

Full Text: 2009\J Haz Mat172, 1041.pdf

Abstract: Crosslinked chitosan/poly(vinyl alcohol) (PVA) beads were prepared by suspension of chitosan-PVA aqueous solution in a mixture of toluene and chlorobenzene. Some quantity of the water was distilled out as an azeotrope along with toluene-chlorobenzene and the droplets were chemically crosslinked by adding glutaraldehyde. The prepared crosslinked beads were characterized by FTIR, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The developed beads were used as an adsorbent for the adsorption of Cd(II) from wastewater. Effect of time, temperature, pH, adsorbent dose and adsorbate concentration on the adsorption of Cd(II) were investigated in batch process and pseudo-first and pseudo-second-order kinetic models were also evaluated. The equilibrium adsorption obeyed Langmuir and Freundlich isotherms as well as the thermodynamic parameters such as ΔGº, ΔHº, and ΔSº were calculated. From thermodynamic data, it was found that the adsorption process was endothermic and spontaneous. The maximum adsorption of Cd(II) ions was found to be 73.75% at pH 6 and indicated that developed material could be effectively utilized for the removal of Cd(II) ions from wastewater. (C) 2009 Elsevier B.V. All rights reserved.

Keywords: Adsorbent, Adsorbent Dose, Adsorption, Adsorption, Alcohol, Aqueous Solution, Aqueous-Solution, Batch, Batch Process, Beads, Cadmium, Cd(II), Cd(II) Ion, Cd(II) Ions, Chitosan Beads, Chitosan, PVA Beads, Concentration, Congo Red, Crosslinking, Data, Electron Microscopy, Endothermic, Equilibrium, Freundlich, Freundlich Isotherms, FTIR, Glutaraldehyde, Heavy-Metals, Hexavalent Chromium, Hydrogel Beads, Ions, Isotherms, Kinetic, Kinetic Models, Langmuir, Langmuir and Freundlich Isotherms, Models, pH, Pseudo Second Order, Pseudo-First and, Pseudo-Second-Order, Recovery, Removal, Rights, Scanning Electron Microscopy, SEM, Solution, Spontaneous, Suspension, Temperature, Thermodynamic, Thermodynamic Data, Thermodynamic Parameters, Toluene, Wastewater, Water, X-Ray, X-Ray Diffraction, XRD

? Guaracho, V.V., Kaminari, N.M.S., Ponte, M.J.J.S. and Ponte, H.A. (2009), Central Composite experimental design applied to removal of lead and nickel from sand. Journal of Hazardous Materials, 172 (2-3), 1087-1092.

Full Text: 2009\J Haz Mat172, 1087.pdf

Abstract: The aim of this study was to apply Central Composite experimental design in the removal of lead and nickel ions from sand by electrokinetic remediation. Sand was used for an initial study since it is inert, thus making it possible to analyze the parameters influencing the process. Central Composite Design was used to create an experimental program to provide data to model the effects of various factors on removal efficiency. The variables chosen were ion concentration (C), applied potential (E) and time (t). The mathematical relationship between removal efficiency and three significant independent variables can be approximated by a second-order quadratic model. Response Surface Methodology (RSM) was used to describe the individual and interactive effects of three variables at five levels, combined according to a Central Composite Design. This study has shown that Central Composite Design can be applied to the removal of lead and nickel ions from sand, and it is an economical way of obtaining the maximum amount of information with the fewest experiments. (C) 2009 Elsevier B.V. All rights reserved.

Keywords: Recovery of Lead and Nickel Ions, Electrokinetic Soil Remediation, Central Composite Design, Response Surface Methodology, Metal-Contaminated Soils, Industrial Waste-Water, Electrokinetic Remediation, Heavy-Metals, Optimization, Methodology

? Chen, A.H. and Chen, S.M. (2009), Biosorption of azo dyes from aqueous solution by glutaraldehyde-crosslinked chitosans. Journal of Hazardous Materials, 172 (2-3), 1111-1121.

Full Text: 2009\J Haz Mat172, 1111.pdf

Abstract: The crosslinked chitosan microparticles prepared through homogeneous coupling reaction and microparticle formation using a sodium hydroxide solution showed the largest adsorbed amounts toward the RB5 and 3R dyes than those from the three other methods through heterogeneous coupling reaction and microparticle formation using sodium hydroxide or sodium tripolyphosphate solutions. The dynamical experimental study showed that the dye adsorption accurately followed the second-order adsorption process. The experimental isotherm data were analyzed using three isotherm models, namely, Langmuir, Freundlich, and Dubinin-Radushkevich. The results revealed that the adsorption behavior of the RB5 and 311 dyes on the microparticles fitted well with the Langmuir model. In addition, the mean adsorption energy (E) from the Dubinin-Radushkevich isotherm and the activation energy (E-a) from Arrhenius equation indicated that the adsorption process might be the dual nature of the process, physisorption and chemisorption, and was predominant on the chemisorption process The competitive adsorption showed that the adsorption of the 3R dye on the microparticles in the mixture solution was much more affected by the existence of the RB5 dye than the other way around. Furthermore, it was also found that the crosslinked chitosan microparticles can be regenerated and reused for dye adsorption. (C) 2009 Elsevier B.V. All rights reserved.

Keywords: Biosorption, Azo Dye, Crosslinked Chitosan Microparticle, Competition, Desorption, Model Anionic Dye, Reactive Dye, Acid Dye, Comparative Adsorption, Waste-Water, Pb(II) Ions, Eosin-Y, Beads, Removal, Metal

? Mokaddem, H., Sadaoui, Z., Boukhelata, N., Azouaou, N. and Kaci, Y. (2009), Removal of cadmium from aqueous solution by polysaccharide produced from Paenibacillus polymyxa. Journal of Hazardous Materials,