Personal Research Database

Full Text: J\J Haz Mat36, 249.pdf

Abstract: The understanding of the leaching behaviour of municipal solid waste (MSW) incinerator flyash is important from the environmental point of view, particularly for landfill disposal and also for hazardous metal detoxification or for metal recovery. In this paper, the leachability of metals from MSW flyash was compared for various solvents, including H₂O, NaOH, HCl, H₂SO₄ HClO₄, HNO₃ and HAc. Hydrochloric acid was found to be a most effective solvent to remove heavy metals from flyash. The experiments with HCl concentrations from 0 to 6 M showed that HCl concentration does not affect the leachability of most elements above 0.5 M HCl. For lead and copper, leachability increases up to 1 M HCl, while for iron leachability increases with increasing HCl concentration through the whole concentration range tested, Silica gel was found to form quickly in concentrated HCl solutions, and caused poor solution filterability. The HCl-leached residue was shown to be non-hazardous.

Baeyens, J. and van Puyvelde, F. (1994), Fluidized bed incineration of sewage sludge: A strategy for the design of the incinerator and the future for incinerator ash utilization. Journal of Hazardous Materials, 37 (1), 179-190.

Full Text: J\J Haz Mat37, 179.pdf

Abstract: In 1991, the sewage sludge production from municipal sewage treatment plants in Flanders was about 45000 ton/year in terms of dry solids.

With additional sewage treatment plants being built, the sludge quantity will dramatically increase. Per capita and per day, about 50 grams of dry solids will be produced, to reach a total production in excess of 100000 ton/year by the end of the century.

Most of the sludge is currently disposed by landfill, but it has become more and more difficult to find suitable sites for landfill, particularly in and around large cities. Reduction of the sludge volume to be disposed, therefore, is often a matter of primary concern. of the new processes developed to ensure the safe disposal of sludges from municipal and industrial effluent treatment, plants, the fluidized bed incinerator is attracting increasing interest.

This paper presents a practical strategy for their design and concentrates on the eventual utilization and beneficiation of incinerator ash, which can reduce the total cost of sludge treatment and disposal.

? Shonnard, D.R. and Bell, R.L. (1994), The effects of nonlinear sorption on the diffusion of volatile organic-compounds from air-dry soils: A theoretical study. Journal of Hazardous Materials, 37 (3), 397-414.

Full Text: 1994\J Haz Mat37, 397.pdf

Abstract: The effects of nonlinear (Brunauer-Emmett-Teller, BET) sorption on the rates of diffusion of volatile organic compounds (VOCs) within and from uniformly contaminated air-dry soils were evaluated by numerical solution of the one-dimensional gas-phase diffusion equation. A dimensionless sorption parameter, which accounts for the importance of BET sorption on the diffusive transport, was identified. Numerical simulations demonstrated that the dimensionless gas-phase and total-soil concentration profiles, and the dimensionless emission rates of VOC from the soil surface, varied in response to changes in the initial concentration of the VOC in the soil, in marked contrast with the case of linear sorption of the VOC. The sensitivity of the numerical results towards the BET sorption parameters in the model was evaluated. A linearization step in the derivation of the continuity equation of diffusion and BET sorption was used to obtain an analytical solution for the soil surface flux of VOC to the atmosphere, by substituting a linear sorption isotherm for the BET isotherm. The errors associated with this step were evaluated and the deviations were found to be < 20% for all cases tested in comparison to the full numerical solutions.

Keywords: Changes, Comparison, Continuity, Diffusion, Gas Phase, Gas-Phase, Isotherm, Linear Sorption, Model, Moisture, Organic Compounds, Sensitivity, Soil, Soils, Sorption, Sorption Isotherm, Surface, Transport, Vapor, VOC, VOCs, Volatile Organic Compounds

? Campagnolo, J.F. and Akgerman, A. (1994), Investigation of normal-hexane and nitrogen adsorption onto soil constituents and constituent mixtures. Journal of Hazardous Materials, 37 (3), 415-430.

Full Text: 1994\J Haz Mat37, 415.pdf

Abstract: Vapor-phase adsorption of normal hexane onto some common soil constituents and simple mixtures of these constituents at 27-degrees-C was studied. Experiments were conducted at zero relative humidity. The constituents can be classified as clays, organic matter and sand. Only the clays were significant adsorbents in both the pure constituent and mixture experiments. In all cases the adsorption- isotherms had the Type II sigmoid shape. Adsorbent surface areas were estimated from the two-parameter BET adsorption model. Adsorption capacity, reflected by surface area, of the mixtures could be characterized almost completely by clay content alone. The clays, although possessing much different capacities to adsorb hexane when expressed on a mass basis, exhibited approximately equal adsorption capacities relative to their N2/BET surface areas. Accordingly, the various dry-clay adsorption isotherms when plotted as relative capacity (amount of hexane adsorbed divided by N2/BET surface area) versus normalized concentration were seen to collapse roughly upon one another for a large part of the concentration range. Furthermore, clay BET surface areas estimated from hexane adsorption at 27-degrees-C were consistently seen to be approximately 0.73 times that of the value from N2 adsorption.

Keywords: Adsorbent, Adsorbents, Adsorption, Adsorption Capacities, Adsorption Capacity, Adsorption Isotherms, Adsorption Model, Capacity, Clay, Experiments, Humidity, Isotherms, Mixtures, Model, Nitrogen, Organic Matter, Organic-Matter, Sand, Soil, Sorption, Surface, Vapor-Phase Adsorption, Water

? Reible, D.D. (1994), Loss of methyl-bromide to the atmosphere during soil fumigation. Journal of Hazardous Materials, 37 (3), 431-444.

Full Text: 1994\J Haz Mat37, 431.pdf

Abstract: Models of soil vapor transport were developed and applied to the prediction of atmospheric emissions of methyl bromide during soil fumigation. With effective cover placement and good injection depth control estimated cumulative methyl bromide losses to the atmosphere after 14 days ranged from 26% to 65% of that originally injected under a variety of injection conditions. The rate of emission after 14 days is small and was neglected. The best estimate of cumulative methyl bromide losses to the atmosphere under current emission practices is about half of that injected, in good agreement with estimates by Watson et al. [1] based on global concentrations of methyl bromide. The model suggests that deep injection with surface porosity control by moisture addition or use of low permeability covers could be an effective means of minimizing losses to the atmosphere during soil fumigation. Emissions would also be the smallest for high organic carbon content soils which tend to increase both reactivity and retardation due to sorption.

Keywords: Agreement, Bromide, Carbon, Control, Current, Model, Models, Placement, Porosity, Practices, Prediction, Reactivity, Soil, Soils, Sorption, Surface, Transport, Vapor

? Li, Y.C. and Gupta, G. (1994), Adsorption of hydrocarbons by clay-minerals from gasoline. Journal of Hazardous Materials, 38 (1), 105-112.

Full Text: 1994\J Haz Mat38, 105.pdf

Abstract: Adsorption of six hydrocarbons (BTEXs - benzene, toluene, ethylbenzene, p-xylene, m-xylene, and o-xylene) from gasoline by three clay minerals (montmorillonite, illite and kaolinite) was studied using the batch equilibrium method. The clays were treated to remove organic matter before use. Four concentrations of gasoline (10, 50, 100, 150 mul/l) in water were used to get a range in concentration of the BTEXs (0.22-10.65 mul/l). Freundlich adsorption coefficient (K) for each hydrocarbon was consistently higher with montmorillonite than with illite and kaolinite. The presence of competing species resulted in a decrease of K values for toluene from 2.42 from a single solute, to 0.81 for the hydrocarbons mixture (containing benzene + toluene + xylenes) and to 0.69 for gasoline.

Keywords: Adsorption, Batch, Benzene, Clay, Clay Minerals, Equilibrium, Ethylbenzene, Freundlich, Gasoline, Hydrocarbons, Kaolinite, Mixtures, Montmorillonite, Organic Matter, Partition, Presence, Soil Organic-Matter, Sorption, Toluene, Values, Water

? Zytner, R.G. (1994), Sorption of benzene, toluene, ethylbenzene and xylenes to various media. Journal of Hazardous Materials, 38 (1), 113-126.

Full Text: 1994\J Haz Mat38, 113.pdf

Abstract: The sorption and desorption characteristics of the major components of gasoline were determined for five media; sandy loam soil, organic top soil, clay soil, peat moss and granular activated carbon (GAC). Emphasis was placed on the sorption of benzene, toluene, ethylbenzene and xylenes (BTEX), the aromatic hydrocarbons contained in gasoline. The results showed that the Freundlich isotherm satisfactorily described the sorption and desorption of dissolved BTEX on the media tested. The organic carbon content of the media was an important factor in both sorption and desorption, with the order of sorption preference being GAC, peat moss, organic top soil, clay soil and sandy loam soil. The soil-water partition coefficient (K(oc)) for the BTEX compounds and Total BTEX suggests that the BTEX compounds will migrate quickly through soil, with benzene being the fastest followed by toluene, m-, p- and o-xylenes and ethylbenzene.

Keywords: Activated Carbon, Adsorption, Benzene, Btex, Carbon, Chemicals, Clay, Coefficients, Desorption, Ethylbenzene, Freundlich, Freundlich Isotherm, GAC, Granular Activated Carbon, Groundwater, Hydrocarbons, Isotherm, Media, Model, Partition, Partition Coefficient, Peat, Peat Moss, Preference, Soil, Soil Water, Soils, Sorption, Toluene

? Yang, X.Q., Erickson, L.E. and Fan, L.T. (1994), Dispersive convective characteristics in the biorestoration of contaminated soil with a heterogeneous formation. Journal of Hazardous Materials, 38 (1), 163-185.

Full Text: 1994\J Haz Mat38, 163.pdf

Abstract: A hydrochemical model comprising a set of coupled partial differential equations has been proposed for the bioremediation of contaminated soil with a heterogeneous formation. The soil bed is a layer of water-saturated porous medium with dominant bypassing flow. Inside the layer, the groundwater flow is relatively slow such that the magnitudes of convection and dispersion are of the same order. This model describes, both spatially and temporally, the contaminant fate, microorganism growth and oxygen consumption. The results of simulation indicate that the velocity of the groundwater flow affects significantly the rate of contaminant depletion; the higher the velocity, the greater the availability of oxygen and the faster the substrate consumption. When the velocity is low, an anaerobic zone is generated in the clay layer, thereby rendering the biodegradation rate oxygen limited and, in turn, prolonging the remediation time.

Keywords: Anaerobic, Aquifer Material, Biodegradation, Bioremediation, Clay, Consumption, Contaminant, Contaminated Soil, Groundwater, Growth, Heterogeneous, Intraparticle Diffusion, Model, Porous-Media, Remediation, Simulation, Soil, Solute Transport, Sorption, Water-Flow

? Aminabhavi, T.M. and Munnolli, R.S. (1994), An assessment of chemical compatibility of bromobutyl rubber, chlorosulfonated polyethylene and epichlorohydrin membranes in the presence of some hazardous organic liquids. Journal of Hazardous Materials, 38 (2), 223-242.

Full Text: 1994\J Haz Mat38, 223.pdf

Abstract: The present study addresses the currently available polymeric materials which are possibly used as liner materials in waste chemical ponds against hazardous organic liquids. To assess the chemical compatibility, bromobutyl rubber (BIIR), chlorosulfonated polyethylene and epichlorohydrin (ECO) are selected for exposure to chloroalkanes and non-chlorinated liquids. These solvents come under the category of hazardous liquids and protection from their contamination to ground water and other aquatics is an important hygienic requirement. One of the possible means of studying the chemical compatibility of the liner membranes against such liquids is to investigate their transport characteristics into the membrane matrices. Thus, results of sorption and diffusion of the above-mentioned systems in the temperature interval 25-60-degrees-C are presented using the sorption gravimetric technique. These results are analyzed by using the Fickian equation. The dependence of transport coefficients on the size and shape of the liquid molecules is discussed. Transport results are greatly influenced by the type of the polymer-solvent interactions in addition to the size of the liquid molecules. The Arrhenius activation parameters are estimated from a temperature dependence of sorption, diffusion and permeation coefficients. Enthalpy and entropy of sorption for the polymer-solvent systems have also been studied. Computed parameters and experimental results are used to discuss the transport mechanism in terms of the type and nature of the polymer membranes and the solvent molecules. Volume dilation of the polymers in the presence of the chosen liquid media has been measured. BIIR and ECO membranes appeared to be reactive toward tetrahydrofuran at 60-degrees-C.

Keywords: Activation, Assessment, Butadiene Rubber, Contamination, Dependence, Diffusion, Elastomers, Exposure, Fickian, Ground Water, Interactions, Mechanism, Media, Membrane, Membranes, Permeation, Polymer, Polymer Membranes, Presence, Protection, Rubber, Sorption, Systems, Technique, Temperature, Transport, Water

? Gioia, F., Gallagher, E.J. and Famiglietti, V. (1994), Effect of hydrogen pressure on detoxification of 1,2,3-trichlorobenzene by catalytic hydrodechlorination with both unsulphided and sulfided Ni-Mo/γ-Al₂O₃ catalyst. Journal of Hazardous Materials, 38 (2), 277-291.

Full Text: 1994\J Haz Mat38, 277.pdf

Abstract: A process which has large potential as a disposal method of organic toxic wastes is hydrotreating. The present work has investigated the effects of hydrogen pressure on the catalyic hydrodechlorination of 1,2,3-trichlorobenzene using the unsulphided and sulphided forms of Ni-Mo/gamma-Al₂O₃ catalyst. All the experiments were carried out in a stirred autoclave at a constant temperature of 330-degrees-C and at the hydrogen pressures (kept constant during each experiment) in the range 35 less-than-or-equal-to p(H2) less-than-or-equal-to 100 bar. Hexadecane was used as reaction medium. The experimental results allowed us to identify the reaction networks: (i) for the unsulphided form of the catalyst, there were parallel reactions to 1,2 and 1,3 dichlorobenzene. Both these species then reacting with hydrogen to form chlorobenzene, which in turn formed benzene; (II) the sulphided form of the catalyst holds the same network but with one extra reaction from benzene to hydrocracking products. With the help of the Langmuir-Hinshelwood theory it was possible to gain an insight into the mechanism of the single reactions which form the networks: hydrogen is adsorbed according to a Langmuir-type dissociative adsorption and the rate determining step is the surface reaction. Finally it was demonstrated that the major dechlorination path of the reaction network is pressure independent with sulphided catalyst.

Keywords: Adsorption, Benzene, Benzenes, Catalyst, Chlorobenzene, Dechlorination, Detoxification, Disposal, Experiments, Hydrodechlorination, Hydrodesulfurization, Insight, Langmuir-Hinshelwood, Mechanism, Networks, Pressure, Process, Surface, Temperature, Theory, Work

? Peters, R.W. (1994), special issue - adsorption of priority pollutants at the solid-liquid interface - preface. Journal of Hazardous Materials, 38 (3), 351-352.

Full Text: 1994\J Haz Mat38, 351.pdf

Keywords: Adsorption

? Shen, B.C., Fan, L.T. and Chen, W.Y. (1994), Stochastic modeling of adsorption in a batch system. Journal of Hazardous Materials, 38 (3), 353-371.

Full Text: 1994\J Haz Mat38, 353.pdf

Abstract: The adsorption of molecules of organic or inorganic compounds in an aqueous solution onto granular activated carbon involves a sequence of steps including: transfer of the molecules from the bulk phase of solution through the relatively stagnant layer of solution adjacent to the external surface and solution in macropores and micropores of the pellet of activated carbon and occupation of the active sites on the inside of the pellet by the molecules. The present work analyzes and models this sequence of steps by resorting to the stochastic population balance of the numbers of molecules of adsorbate in the three states. The first comprises the bulk phase of the solution; the second, the layer of solution adjacent to the external surface and the solution in the macropores; and the third, the active sites on the inside surfaces of the micropores. The master equation has been derived for the case of a single adsorbate compound. The equations for the means, variances, and covariances of the random variables have been obtained through the system size expansion of the master equation. At equilibrium, the equations for the means reduce to the equation of the Langmuir isotherm. The unknown parameters in the equations for the means have been estimated by comparing the calculated results with the experimental data. These parameters have been adopted to predict the evolution of variances and covariances of the numbers of adsorbate molecules in the three states.

Keywords: Activated Carbon, Adsorption, Aqueous Solution, Carbon, Equilibrium, Evolution, Granular Activated Carbon, Isotherm, Langmuir, Langmuir Isotherm, Modeling, Models, Occupation, Population, States, Stochastic, Surface, Third, Transfer, Work

? Vidic, R.D., Suidan, M.T., Sorial, G.A. and Brenner, R.C. (1994), Effect of molecular-oxygen on adsorptive capacity and extraction efficiency of granulated activated carbon for 3 ortho-substituted phenols. Journal of Hazardous Materials, 38 (3), 373-388.

Full Text: 1994\J Haz Mat38, 373.pdf

Abstract: Adsorptive capacity of activated carbon for several organic compounds was found to be strongly influenced by the presence of molecular oxygen. This influence is manifested by the polymerization of adsorbate on the surface of activated carbon. As a result, GAC exhibits much higher adsorptive capacities for these compounds under oxic rather than under anoxic conditions. Therefore, a new experimental procedure for conducting adsorption isotherm tests is investigated in this work. The results of kinetic experiments show that this polymerization of adsorbate proceeds at a very slow rate which extends the time required for equilibrium conditions to be established. Extraction efficiency obtained for GAC used in anoxic isotherm experiments were significantly higher than those obtained for GAC used in isotherm experiments conducted in the presence of molecular oxygen.

Keywords: Activated Carbon, Adsorption, Adsorption Isotherm, Anoxic, Beds, Breakthrough Curves, Capacity, Carbon, Design, Efficiency, Equilibrium, Experiments, Extraction, GAC, Influence, Isotherm, Kinetic, Organic Compounds, Oxic, Phenols, Pore-Size Distribution, Presence, Single Solutes, Surface, Work

? Fox, P. and Suidan, M.T. (1994), Adsorption of biologically inhibitory compounds as a process-control mechanism in biological reactors. Journal of Hazardous Materials, 38 (3), 389-404.

Full Text: 1994\J Haz Mat38, 389.pdf

Abstract: An innovative reactor design that decouples biological removal mechanisms from physical removal mechanisms has demonstrated promise for the treatment of wastewaters containing high concentrations of inhibitory compounds. Inhibition and toxicity prevent treatment of such wastewaters in conventional biological reactors. The reactor design consists of a high-rate biological reactor with a granular activated carbon (GAC) adsorber inserted into the recycle line of the biological reactor. Partial replacement of GAC from the GAC adsorber provides a mechanism for controlling the concentration of inhibitory compounds in the biological reactor. As a process control parameter, GAC replacement can be used to maintain the concentration of inhibitory compounds in a range optimal for growth and acclimation. GAC replacement is also varied in response to changes in the influent loading and can be used to provide rapid recovery from shock loadings. Agreement between isotherm studies and experimental data from pilot-scale systems was observed when the average GAC particle residence was greater than 3.75 days. Isotherm studies may be used to design the GAC adsorber and predict optimal operating conditions. The concept of using an adsorption process to optimize biological removal provides an environmentally sound treatment alternative for many high-strength wastewaters.

Keywords: Activated Carbon, Adsorption, Adsorption Process, Bed Anaerobic Reactors, Biological Removal, Carbon, Changes, Control, Design, Gac, Granular Activated Carbon, Growth, Isotherm, Mechanism, Mechanisms, Media, Operating Conditions, Process, Recovery, Recycle, Removal, Replacement, Systems, Toxicity, Treatment, Waste-Water, Wastewaters

? Dougherty, E.J., Mcpeters, A.L., Overcash, M.R. and Carbonell, R.G. (1994), Sorption processes of 2,3,7,8-tetrachlorodibenzo-p-dioxin on soil in the presence of organic liquids. Journal of Hazardous Materials, 38 (3), 405-421.

Full Text: 1994\J Haz Mat38, 405.pdf

Abstract: Soil contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) often contains organic solvents as co-contaminants or as part of the clean-up process. The rate constants for adsorption and desorption of TCDD to Norfolk loamy sand in four organic liquids have been determined from a kinetic analysis of new experimental data. Intraparticle diffusion and external mass transfer limitations played a minor role in the mechanisms of adsorption and desorption. Screening studies have also been carried out in order to determine the efficacy of 15 single organic solvents and seven solvent mixtures in TCDD removal from Norfolk loamy sand. Low-molecular weight and low-viscosity solvents removed the most TCDD during the duration of the experiment. The addition of low-molecular weight alcohols to more viscous solvents greatly increased the capacity for TCDD removal.

Keywords: Adsorption, Alcohols, Analysis, Capacity, Chemicals, Desorption, Diffusion, Efficacy, Environment, Intraparticle Diffusion, Kinetic, Limitations, Mass Transfer, Mechanisms, Mixtures, Para-Dioxin, Process, Rate Constants, Removal, Sand, Soil, Sorption, Systems, TCDD, Transfer

? Liu, J.C. and Huang, C.P. (1994), Adsorption of phenols onto hydrous ZnS_(S): effect of cosolvent and temperature. Journal of Hazardous Materials, 38 (3), 423-438.

Full Text: 1994\J Haz Mat38, 423.pdf

Abstract: The adsorption of phenols onto hydrous ZnS_(s) surface in the presence of cosolvent, namely, methanol, was studied. Adsorption of phenols onto hydrous ZnS_(s) surface follows a linear relationship between adsorption density and equilibrium concentration. In the presence of a cosolvent, the extent of phenol adsorption decreases except catechol. Apparently, the adsorption of phenols is determined by hydrophobic partition whereas the adsorption of catchol is governed by specific chemical interaction. Adsorption of phenols is an endothermic process; the extent of phenol adsorption increases with increasing temperature. This is attributed to the hydrophobic characteristics of the phenol adsorbents.

Keywords: Adsorbents, Adsorption, Adsorption Density, Endothermic, Equilibrium, Hydrophobic, Hydrophobic Organic-Chemicals, Interaction, Oxidation, Partition, Phenol, Phenol Adsorption, Phenols, Presence, Process, Relationship, Soils, Solubility, Sorption, Surface, Systems, Temperature, Transport, Water

Chang, C. and Ku, Y. (1994), Adsorption kinetics of cadmium chelates on activated carbon. Journal of Hazardous Materials,