Personal Research Database

Full Text: 2001\J Haz Mat84, 135.pdf

Abstract: Chlorinated solvents partition readily into the vapor-phase in unsaturated soils. Sorption from the vapor-phase affects both transport and recovery. The Brunauer-Emmett-Teller (BET) isotherm has been used to model adsorption of chlorinated solvent vapors; however, the BET equation is not accurate above reduced vapor pressures (p/p(sat)) of 0.35. New measurements of chlorinated alkane sorption have been used with a modified BET equation (MBET) to model the adsorption isotherms for five solvents. The MEET equation was found to fit experimental data accurately, especially at high reduced vapor pressures. The capacity of sandy loam soil to adsorb organic vapors decreased with increasing water content, probably due to less soil surface available for sorption, This effect is most evident at reduced vapor pressures greater than 0.5. Adsorption is related to distribution of excess surface energy, the number of molecular layers of water sorbed at the surface, and solute polarity. Results suggest that water films contain areas of high interfacial energy that interact with solute molecules via induced electrostatic forces. (C) 2001 Elsevier Science B.V. All rights reserved.

Keywords: Adsorption, Adsorption Isotherms, Aquifer, Capacity, Carbon Halogenated Solvents, Chlorinated Solvents, Diffusion, Distribution, Electrophysical Sorption, Isotherm, Isotherms, Matter, Model, Modified, Moisture, Organic Vapors, Partition, Phase Sorption, Presence, Recovery, Rights, Soil, Soil Moisture, Soils, Sorption, Surface, Surface Energy, Transport, Trichloroethylene, Water

? Lin, S.H. and Huang, C.H. (2001), Adsorption of hydrazoic acid from aqueous solution by macroreticular resin. Journal of Hazardous Materials, 84 (2-3), 217-228.

Full Text: 2001\J Haz Mat84, 217.pdf

Abstract: Sodium azide is a key component in the automobile air bag. When dissolved in aqueous solution, it reacts rapidly with water to form hydrazoic acid which is a highly toxic chemical and is strongly regulated by government. In the present study, adsorption of hydrazoic acid from aqueous solution by macroreticular resin is investigated. This method can provides a convenient means for dealing with the toxic hydrazoic acid. Experimental tests of batch equilibrium adsorption and continuous column adsorption of hydrazoic acid were conducted and the test results were employed to establish adsorption isotherm and to evaluate the column adsorption efficiency. The test results revealed that the multilayer adsorption isotherms, like the modified Langmuir or Jossens model, are needed to adequately describe the hydrazoic acid adsorption equilibrium between the liquid and solid (resin) phases. In the column adsorption process, a theoretical model was adopted for representing the hydrazoic acid change in the aqueous solution exiting the column and the verified theoretical model significantly facilitates prediction of adsorption breakthroughs and column design. Regeneration of exhausted resin was investigated. Solution of 10% (w/w) NaCl was found to be a very efficient regenerant. (C) 2001 Published by Elsevier Science B.V.

Keywords: Acid, Adsorption, Adsorption Equilibrium, Adsorption Isotherm, Adsorption Isotherms, Adsorption Process, Aqueous Solution, Batch, Change, Column, Column Adsorption, Design, Efficiency, Equilibrium, Hydrazoic Acid, Isotherm, Isotherms, Key, Langmuir, Macroreticular Resin, Model, Modified, Prediction, Process, Regeneration, Resin, Sodium Azide, Test, Theoretical Model, Water

? Moo-Young, H., Myers, T., Tardy, B., Ledbetter, R., Vanadit-Ellis, W. and Sellasie, K. (2001), Determination of the environmental impact of consolidation induced convective transport through capped sediment. Journal of Hazardous Materials, 85 (1-2), 53-72.

Full Text: 2001\J Haz Mat85, 53.pdf

Abstract: The presence of contaminated sediment poses a barrier to essential waterway maintenance and construction in many ports and harbors, which support 95% of US foreign trade. Cost effective solutions to remediate contaminated sediments in waterways need to be applied. Capping is the least expensive remediation alternative available for marine sediments that is unsuitable for open water disposal. Dredged material capping and in situ capping alternatives, however, are not widely used because regulatory agencies are concerned about the potential for contaminant migration through the caps. Numerous studies have been conducted on the effects of diffusion through caps, however, there is a lack of experimental data documenting the effects of consolidation induced transport of contaminants through caps. This study examines consolidation induced convective contaminant transport in capped sediment utilizing a research centrifuge. In this study, consolidation induced convective transport was modeled for 7 h at 100 x g, which modeled a contaminant migration time of 8 years for a prototype that was 100 times larger than the centrifuge model. In this study, hydrodynamic dispersion was a function of the seepage velocity. And, advection and dispersion dominated the migration of contaminants. Centrifuge model results were compared to an analytical solution for advection and dispersion. The advection-dispersion equation demonstrated that the centrifuge test is a conservative estimate for predicting contaminant transport. In conducting sensitivity analysis of the advection-dispersion equation to the centrifuge modeling, as hydrodynamic dispersion decreased, the time for contaminant breakthrough increased. Moreover, as the sediment to water distribution coefficient increased, the contaminant concentration into the overlying water decreased. (C) 2001 Elsevier Science B.V. All rights reserved.

Keywords: Analysis, Breakthrough, Capping, Capping Layer, Centrifuge, Consolidation, Contaminant Transport, Contaminants, Diffusion, Diffusion Adsorption, Disposal, Distribution, Distribution Coefficient, Efficiency, Environmental, Environmental Impact, Function, Impact, In Situ, Marine, Migration, Model, Modeling, Need, Presence, Remediation, Research, Research Centrifuge, Rights, Sediment, Sediments, Sensitivity, Sensitivity Analysis, Support, Test, Transport, US, Water

Mulligan, C.N., Yong, R.N. and Gibbs, B.F. (2001), Heavy metal removal from sediments by biosurfactants. Journal of Hazardous Materials, 85 (1-2), 111-125.

Full Text: J\J Haz Mat85, 111.pdf

Abstract: Batch washing experiments were used to evaluate the feasibility of using biosurfactants for the removal of heavy metals from sediments. Surfactin from Bacillus subtilis, rhamnolipids from Pseudomonas aeruginosa and sophorolipid from Torulopsis bombicola were evaluated using a metal-contaminated sediment (110mg/kg copper and 3300mg/kg zinc). A single washing with 0.5% rhamnolipid removed 65% of the copper and 18% of the zinc, whereas 4% sophorolipid removed 25% of the copper and 60% of the zinc. Surfactin was less effective, removing 15% of the copper and 6% of the zinc. The technique of ultrafiltration and zeta potential measurements were used to determine the mechanism of metal removal by the surfactants. It was then postulated that metal removal by the biosurfactants occurs through sorption of the surfactant on to the soil surface and complexation with the metal, detachment of the metal from the soil into the soil solution and hence association with surfactant micelles. Sequential extraction procedures were used on the sediment to determine the speciation of the heavy metals before and after surfactant washing. The carbonate and oxide fractions accounted for over 90% of the zinc present in the sediments. The organic fraction constituted over 70% of the copper. Sequential extraction of the sediments after washing with the various surfactants indicated that the biosurfactants, rhamnolipid and surfactin could remove the organically-bound copper and that the sophorolipid could remove the carbonate and oxide-bound zinc. Therefore, heavy metal removal from sediments is feasible and further research will be conducted. (C) 2001 Elsevier Science Ltd. All rights reserved.

Keywords: Sediments, Biosurfactants, Remediation, Heavy Metals, Washing

? Kim, S.O. and Kim, K.W. (2001), Monitoring of electrokinetic removal of heavy metals in tailing-soils using sequential extraction analysis. Journal of Hazardous Materials, 85 (3), 195-211.

Full Text: 2001\J Haz Mat85, 195.pdf

Abstract: This research focused on the monitoring of the electrokinetic removal of heavy metals from tailing-soils, and emphasizes the dependency of removal efficiencies upon their physico-chemical states, as demonstrated by the different extraction methods adopted, which included aqua regia and sequential extraction. The tailing-soils examined contained high concentrations of target metal contaminants (Cd = 179 mg kg^-1, Cu = 207 mg kg^-1, Pb = 5175 mg kg^-1, and Zn = 7600 mg kg^-1). The removal efficiencies of the different metals were significantly influenced by their speciations, mobilities and affinities (adsorption capacities) in the soil matrix. The removal efficiencies of mobile and weakly bound fractions, such as the exchangeable fraction were more than 90% by electrokinetic treatment, but strongly bound fractions, such as the organically bound species and residual fraction were not significantly removed (less than 30% removal efficiencies). In accordance with the general sequence of mobilities of heavy metals in soils, the removal efficiencies of more mobile heavy metals (Cd, Cu, and Zn) were higher than that of less mobile heavy metal (Pb). (C) 2001 Elsevier Science B.V. All rights reserved.

Keywords: Adsorption, Adsorption Capacities, Analysis, Cd, Contaminants, Cu, Dependency, Electrokinetic Treatment, Electrokinetics, Extraction, Fraction, Heavy Metal, Heavy Metals, Heavy-Metal, Metal, Metals, Methods, Mine Tailings, Monitoring, Pb, Remediation, Removal, Removal Efficiency, Research, Rights, Sequential Extraction, Soil, Soils, Speciation, Speciations, States, Treatment, Zn

Kim, J.W., Sohn, M.H., Kim, D.S., Sohn, S.M. and Kwon, Y.S. (2001), Production of granular activated carbon from waste walnut shell and its adsorption characteristics for Cu²⁺ ion. Journal of Hazardous Materials, 85 (3), 301-315.

Full Text: J\J Haz Mat85, 301.pdf

Abstract: Production of granular activated carbon by chemical activation has been attempted employing walnut shells as the raw material. The thermal characteristics of walnut shell were investigated by TG/DTA and the adsorption capacity of the produced activated carbon was evaluated using the titration method. As the activation temperature increased, the iodine value increased. However, a temperature higher than 400°C resulted in a thermal degradation, which was substantiated by scanning electron microscopy (SEM) analysis, and the adsorption capacity decreased. Activation longer than 1h at 375°C resulted in the destruction of the microporous structure of activated carbon. The iodine value increased with the increase in the concentration of ZnCl₂ solution. However, excessive ZnCl₂ in the solution decreased the iodine value. The extent of activation by ZnCl₂ was compared with that by CaCl₂ activation. Enhanced activation was achieved when walnut shell was activated by ZnCl₂. Applicability of the activated carbon as adsorbent was examined for synthetic copper wastewater. Adsorption of copper ion followed the Freundlich model. Thermodynamic aspects of adsorption have been discussed based on experimental results. The adsorption capacity of the produced activated carbon met the conditions for commercialization and was found to be superior to that made from coconut shell. (C) 2001 Elsevier Science Ltd. All rights reserved.

Keywords: Activated Carbon, Walnut Shell, Chemical Activation, Adsorption, Cu²⁺ Ion

? Shen, P., Huang, C., Ganguly, C., Gaboriault-Whitcomb, S., Rabideau, A.J. and Van Benschoten, J.E. (2001), Comparison of soluble and immobilized acetate for removing Pb from contaminated soil. Journal of Hazardous Materials, 87 (1-3), 59-72.

Full Text: 2001\J Haz Mat87, 59.pdf

Abstract: Five lead (Pb) contaminated soils were used in a laboratory and modeling study to examine the effects of soluble and immobilized acetate on Pb removal from a contaminated soil as a function of pH. Soluble acetate was added as sodium acetate; immobilized acetate was added in the form of a cation exchange resin. For comparative purposes, Pb adsorption with no acetate also was measured as a function of pH. A surface complexation modeling framework was used to interpret experimental data. Experimental results showed the cation exchange resin was much more effective than soluble acetate in removing Pb from soils due to a strong affinity of the resin for Pb. In addition, concentrations of soluble Pb in resin/soil slurry were very low, minimizing the pollution threat if discharged. As deduced from modeling studies, soluble acetate performed poorly compared to the resin, in part, due to adsorption of the soluble PbAc+ complex. The effectiveness of both soluble and immobilized acetate was diminished below pH 4 as a result of competition by H+ for acetate. Modeling results based on resin affinity for Pb compare well with experimental data for resin/soil mixtures, suggesting that Pb partitioning in resin/soil mixtures may be predicted reasonably well if soil/Pb and resin/Pb partitioning are known. Thus, the modeling approach may be used as a screening tool to determine the performance of alternative resins. (C) 2001 Elsevier Science B.V. All rights reserved.

Keywords: Acetate, Adsorption, Cadmium, Cation Exchange, Comparative, Comparison, Competition, Complexation, Contaminated Soil, Decontamination, EDTA, Effectiveness, Exchange, Function, Lead, Mixtures, Modeling, Partitioning, Pb, Pb Adsorption, Performance, pH, Pollution, Recovery, Remediation, Removal, Resin, Resins, Rights, Screening, Soil, Soil Remediation, Soils, Sorption, Surface, Surface Complexation

Rajagopal, C. and Kapoor, J.C. (2001), Development of adsorptive removal process for treatment of explosives contaminated wastewater using activated carbon. Journal of Hazardous Materials, 87 (1-3), 73-98.

Full Text: J\J Haz Mat87, 73.pdf

Abstract: The adsorption characteristics of nitro-organics such as trinitro-toluene (TNT), dinitro-toluene (DNT) and nitrobenzene (NB) on granular activated carbon (GAC) were studied to understand their dynamic adsorption behaviour for dilute aqueous solutions. A model was developed to predict the dynamics of the adsorption process and the effect of various design and operating parameters on adsorption characteristics. The model predictions would provide inputs to design of bench scale and pilot plant scale experiments.

Section 2 of the paper describes the assumptions, predictions, development of the model and its validation with experimental data generated during bench scale and pilot plant trials. Section 3 presents the breakthrough characteristics obtained by conducting experimental runs for GAC of different surface areas from 650 to 1500 m²/g, hydraulic loading rates (HLR) ranging between 12 and 24 m³/h/m², feed concentrations from 50 to 130 mg/l and bed heights between 300 and 1000 mm for TNT, DNT and NB solutions. The effect of these independent parameters on the breakthrough time, adsorption capacity and the minimum concentration achieved in the effluent was studied and the results obtained are presented in this paper. These indicate that the adsorption capacity goes though a maximum when studied as a function of HLR and feed concentration. The adsorption capacity per unit surface area also shows a maximum around 1000 m²/g. The minimum bed height required for meeting environmental effluent discharge limit of 1 ppm was experimentally found to be about 800 mm. These results compare well with the predictions based on the model developed for column adsorption process. Data from these experimental runs and the model predictions have been used to optimise various parameters for the design of a pilot plant unit with 200 l per hour capacity.

Keywords: Activated Carbon, Nitro-Organics, Dynamic Adsorption, Model

Ajmal, M., Rao, R.A.K., Ahmad, R., Ahmad, J. and Rao, L.A.K. (2001), Removal and recovery of heavy metals from electroplating wastewater by using Kyanite as an adsorbent. Journal of Hazardous Materials, 87 (1-3), 127-137.

Full Text: J\J Haz Mat87, 127.pdf

Abstract: Kyanite, a commercial mineral has been utilized as an adsorbent for the removal of heavy metals, such as Ni(II), Zn(II), Cr(VI) and Cu(II) from electroplating wastewater. The effect of contact time, pH, concentration, adsorbent doses, particle size of the adsorbent, salinity and hardness, both in natural and wastewater on the adsorption of Cu(II) have been studied in detail. The adsorption of metal ions seems to be an ion exchange process. The adsorbed metals ions from electroplating wastewater were recovered by batch as well as column operation using dilute HCl solution. The column operation was found to be more effective compared to batch process. (C) 2001 Elsevier Science B.V. All rights reserved.

Keywords: Adsorption, Kyanite, Desorption, Batch Process, Adsorption, Batch, Copper(II), Water

? Arienzo, M., Chiarenzelli, J. and Scrudato, R. (2001), Remediation of metal-contaminated aqueous systems by electrochemical peroxidation: an experimental investigation. Journal of Hazardous Materials, 87 (1-3), 187-198.

Full Text: 2001\J Haz Mat87, 187.pdf

Abstract: An innovative technology, electrochemical peroxidation (ECP), was investigated for remediation of mixed metal-contaminated aqueous systems by application of direct electric current to steel electrodes and of dilute H₂O₂ solution to promote Fenton’s reactions, forming sparingly soluble solid hydrous ferric oxides (HFO). Bench scale experiments evaluated the sorption and distribution of As, Be, Cd, Cr, Cs, Cu, Li, Ni, Pb, Se, V, and Zn among the soluble and solid state HFO formed as part of the ECP process. The effects of pH, hydrogen peroxide concentrations and electric current process times on the efficiency of metal removal were studied. The potential of this technology was demonstrated by effective removal at pH 3.5-4.6 and within 3 min of 0.25 A dc + 100 mg H₂O₂ l^-1, of As, Cr, Pb, Se and V with complete removal of As and Cr, > 95.0%. On increasing the pH of the solution to 6.0, the retention of Be and Cu by HFO increased from 0.9-1.9% at pH 3.5 to 76.8-80.7% at pH 6.0 while concentrations of other metals, such as Pb, decreased due to precipitation of Pb hydroxy-complexes. Experiments in the absence of H₂O₂ revealed that metals were adsorbed by HFO with the same order of affinity, As > Cr > Se > V > Be, as in the presence of H₂O₂, but, with the exception of Cr, to a lesser extent. H₂O₂ used in the ECP process was fundamental to increase the adsorption capacity of HFO for As, from 79.2 to 99.2%, due to the oxidation of As(III) to As(V), which has a stronger affinity for HFO. The reduced adsorption may be related to the formation of poorly ordered crystalline akaganeite, which has a lower surface area than ferrihydrite formed when H₂O₂ was used. The optimal operating conditions were pH < 6.0, an H₂O₂ concentration of 100 mg l^-1 and a current process time not exceeding 3 min. (C) 2001 Elsevier Science B.V. All rights reserved.

Keywords: Acid-Mine Drainage, Adsorption, Adsorption Capacity, Amorphous Iron Hydroxide, Arsenate, Arsenite, As(III), As(V), Capacity, Cd, Cu, Current, Distribution, Efficiency, Electrochemical Peroxidation, Experiments, Ferric, Ferrihydrite, Groundwater, H₂O₂, Heavy Metals, Hydrogen Peroxide, Hydrous Ferric Oxyhydroxides, In-Situ Remediation, Metal, Metal Removal, Metals, Mixed, Operating Conditions, Oxidation, Oxides, Oxyhydroxides, Pb, pH, Precipitation, Presence, Process, Remediation, Removal, Retention, Rights, Scale, Sorption, State, Steel, Surface, Systems, Technology, Water Decontamination, Zn

Rengaraj, S., Yeon, K.H. and Moon, S.H. (2001), Removal of chromium from water and wastewater by ion exchange resins. Journal of Hazardous Materials, 87 (1-3), 273-287.

Full Text: J\J Haz Mat87, 273.pdf

Abstract: Removal of chromium from water and wastewater is obligatory in order to avoid water pollution. Batch shaking adsorption experiments were carried out to evaluate the performance of IRN77 and SKN1 cation exchange resins in the removal of chromium from aqueous solutions. The percentage removal of chromium was examined by varying experimental conditions viz., dosage of adsorbent, pH of the solution and contact time. It was found that more than 95% removal was achieved under optimal conditions. The adsorption capacity (k) for chromium calculated from the Freundlich adsorption isotherm was found to be 35.38 and 46.34 mg/g for IRN77 and SKN1 resins, respectively. The adsorption of chromium on these cation exchange resins follows the first-order reversible kinetics. The ion exchange resins investigated in this study showed reversible uptake of chromium and, thus, have good application potential for the removal/recovery of chromium from aqueous solutions. (C) 2001 Elsevier Science B.V. All rights reserved.

Keywords: Chromium, Ion Exchange Resin, Adsorption Isotherms, Adsorption Kinetics, Adsorption, Recovery, Lead

? Wang, Y.M., Chen, T.C., Yeh, K.J. and Shue, M.F. (2001), Stabilization of an elevated heavy metal contaminated site. Journal of Hazardous Materials, 88 (1), 63-74.

Full Text: 2001\J Haz Mat88, 63.pdf

Abstract: Heavy metal contamination is a common problem that is encountered at many uncontrolled sites: Immobilization is seen as a promising technology for heavy metal remediation. Here, we report a remediation case study of an elevated and multi-metal contaminated site containing Cd, Cu, Ni, Pb, and Zn. In a laboratory test, when the soil was stabilized with reagent grade stabilizers (CaHPO4 and CaCO3), the toxicity characteristic leaching procedure (TCLP) extractable concentrations of Cd, Cu, Pb, and Zn were reduced by more than 87%. The greatest reduction was shown with Pb (99.8%). In the field, Ca(H₂PO₄)₂ due to lower cost and higher solubility replaced CaHPO₄. The TCLP results of the field treatment showed that the extractable concentrations of Cd, Cu, Pb, and Zn were significantly reduced after 30 days of stabilization. The reduction ratios were 98% (Cd), 97% (Cu), 99% (Pb), and 96% (Zn). Although, the reduction ratio of Ni was only 65%, the average extractable concentration was still less than 4.0 mg/l. The percent reduction can, therefore, be considered reasonable. The significant reduction of extractable metal concentrations showed that the stabilizers, a combination of Ca(H₂PO₄)₂ and CaCO₃, successfully immobilized heavy metals on the site. (C) 2001 Elsevier Science B.V All rights reserved.

Keywords: Apatite, Carbonate, Case Study, Cd, Cost, Cu, Grade, Heavy Metal, Heavy Metals, Heavy-Metal, Hydroxyapatite, Immobilization, Leaching, Lead Immobilization, Metal, Metals, Pb, Phosphate, Phosphate, Reduction, Remediation, Rights, Soil, Sorption, Stabilization, TCLP, Technology, Test, Toxicity, Treatment, Zn

? Abanades, S., Flamant, G. and Gauthier, D. (2001), Modelling of heavy meal vaporisation from a mineral matrix. Journal of Hazardous Materials, 88 (1), 75-94.

Full Text: 2001\J Haz Mat88, 75.pdf

Abstract: This study deals with the fundamental aspects of the volatilisation of heavy metals (HM) during municipal solid waste (MS W) incineration. The thermal treatment of a model waste was theoretically and experimentally studied in a fluid-bed. A mathematical model was developed to predict the fate of metallic species according to the main phenomena controlling the process: heat and mass transfer (transport phenomena), chemical reactions involving HM, and mechanism of vapour metal species sorption inside the porous matrix. The model assumes local thermodynamic equilibrium between the vapour and the metal compound on the substrate in the pores of a particle. This approach permits to predict the extent of HM vaporisation from a mineral porous matrix when its physical properties are known. Experimental data concerning CdCl₂ release from an alumina matrix in a 850 degreesC fluidised bed are in good agreement with theoretical results. (C) 2001 Elsevier Science B.V All rights reserved.

Keywords: Adsorption, Agreement, Alumina, Behavior, Cadmium, Capture, Combustion, Equilibrium, Equilibrium-Analysis, Fluidised Bed, Fluidized-Bed, Heavy Metals, Incineration, Mass Transfer, Mathematical Model, Mechanism, Metal, Metal Emissions, Metals, Mineral Matrix, Modelling, Municipal Solid Waste, Physical Properties, Process, Rights, Solid Waste, Solid-Waste Incinerators, Sorbents, Sorption, Speciation, Temperature, Thermal Treatment, Thermodynamic, Transfer, Transport, Treatment, Vaporisation

Rengaraj, S., Moon, S.H., Sivabalan, R., Arabindoo, B. and Murugesan, V. (2002), Removal of phenol from aqueous solution and resin manufacturing industry wastewater using an agricultural waste: Rubber seed coat. Journal of Hazardous Materials,