Personal Research Database

Full Text: J\J Haz Mat80, 175.pdf

Abstract: Chromium contamination of the environment has become an important issue due to the potential health threat it poses. Conventional technologies to clean up heavy metal ions from contaminated waters have been utilized, but these technologies are not cost-effective. However, the use of agricultural waste byproducts for the removal of Cr(VI) from contaminated waters may be a new cost-effective alternative. Oat byproducts from the Juarez Valley in Mexico were studied for the ability to bind Cr(VI) under different temperature and time conditions. The metal binding ability of oat byproducts was calculated from experimental data collected at temperatures of 8, 26, and 54°C, and time exposures of 1, 6, 24, 48, and 72h at each temperature. These results showed that the binding of Cr(VI) to oat biomass increased as time and temperature increased. The bound chromium was recovered from the oat biomass by treatment with 0.2M HCl. Through the use of X-ray absorption spectroscopy, the reduction of Cr(VI) to Cr(III) was determined to occur by the oat byproducts. These results indicate that the use of agricultural waste byproducts could be a better alternative for the removal and subsequent reduction of Cr(VI) to Cr(III) from contaminated waters. (C) 2000 Elsevier Science Ltd. All rights reserved.

Keywords: Chromium(VI), Bioreduction, Oat, Agricultural Byproducts, XANES, EXAFS

? Khalili, N.R., Jain, H. and Arastoopour, H. (2000), Synthesis and characterization of catalysts produced from paper mill sludge I. Determination of NO_x removal capability. Journal of Hazardous Materials, 80 (1-3), 207-221.

Full Text: 2000\J Haz Mat80, 207.pdf

Abstract: Characteristics and catalytic properties of a series of carbon-based catalysts (CBCs) produced from paper mill sludge were evaluated. The major processes involved in the production of the catalysts were chemical activation, impregnation, pyrolysis, and post pyrolysis rinsing. The porous structure, catalytic activity and thermostability of the catalysts were tailored during the production stage by introducing hetero-atoms (zinc chloride, and ferric nitrate) in the carbon structure. Characterization of the produced CBCs included determination of the surface area, pore size, and pore size distribution (PSD) from standard N-2-adsorption isotherm data. The extent of graphitization and the presence of metal crystals were identified from X-ray diffraction (XRD). The limit of the catalyst gasification was estimated from thermogravimetric analysis (TGA) conducted in an oxidized environment. The NOx reduction capability of the produced catalysts was evaluated in the presence of carbon monoxide using a fixed bed reactor. The reaction temperature ranged from 300 to 500 degreesC. It was shown that paper mill sludge is an excellent precursor for the production of CBCs with NO, removal capability of 66-94%. The catalytic capability of the produced CBCs varied according to the method of production, catalyst surface properties (surface area, pore structure, PSD), metal composition and reaction temperature. The highest NOx removal capacity was observed for the catalytic reactions carried out at 400 degreesC. The mesoporous catalyst produced with a Zn:Fe molar ratio of 1:0.5 exhibited the maximum NO_x removal catalytic activity of 94%. (C) 2000 Elsevier Science B,V. All rights reserved.

Keywords: Activated Carbons, Activation, Analysis, Capacity, Carbon, Carbon-Based Catalysts, Carbon-Monoxide, Catalyst, Catalytic Activity, Characterization, Chemical Activation, Composition, Distribution, Environment, Ferric, Fixed Bed, Gasification, Heteroatoms, Impregnation, Iron-Oxide, Isotherm, Mesoporous, Metal, Molar, Nitrate, Nitric-Oxide, NO, NO_x, NO_x Removal, Oxidation, Paper Mill Sludge, Pore Size Distribution, Presence, Production, Pyrolysis, Reduction, Removal, Rights, Sludge, SO₂, Structure, Surface, Synthesis, Temperature, TGA, X-Ray Diffraction, XRD, Zinc, Zinc Chloride

Karim, M.A. and Khan, L.I. (2001), Removal of heavy metals from sandy soil using CEHIXM process. Journal of Hazardous Materials, 81 (1-2), 83-102.

Full Text: J\J Haz Mat81, 83.pdf

Abstract: This paper presents the results of a new process of soil decontamination termed as couple electric-hydraulic gradient assisted by ion exchange medium (CEHIXM) in which a hydraulic gradient is coupled with electric gradient in a non-conventional arrangement for the purpose of electrolysis and ion transport. A suitable ion exchange medium was used to capture and subsequently recover the cations. In this process, heavy metals no longer precipitated in the treated soil near the pretreatment zone. The cations were transported out of the soil and captured in the ion exchange medium. Several laboratory tests were conducted to examine the removal of Pb, Cd, Zn and Mn from sandy soils. The experimental results demonstrated the removal efficiencies more than 97% for all the four heavy metals at an energy expenditure of 345kWh/m³ of soil. (C) 2001 Elsevier Science Ltd. All rights reserved.

Keywords: Soil Remediation, Heavy Metals, Electrolysis, Sandy Soil, Ion Exchange Resin

Wu, F.C., Tseng, R.L. and Juang, R.S. (2001), Enhanced abilities of highly swollen chitosan beads for color removal and tyrosinase immobilization. Journal of Hazardous Materials, 81 (1-2), 167-177.

Full Text: J\J Haz Mat81, 167.pdf

Abstract: The enhancement of abilities for the removal of reactive dyes and immobilization of tyrosinase onto highly swollen chitosan beads was demonstrated compared to the use of common chitosan flakes. Chitosan was prepared from natural cuttlebone wastes. It was shown that the adsorption capacity of dyes at 30 degreesC using swollen chitosan beads was around five times greater than that using common chitosan flakes. The adsorption of dyes using swollen beads was faster by 10-40% depending on the types of dyes. Finally, the capacity of tyrosinase immobilization onto swollen beads was about 14 times greater than chitosan flakes, which was reflected by the higher yield of 3, 4-dihydroxyphenylalanine from tyrosine and ascorbic acid in the heterogeneous catalytic system. (C) 2001 Elsevier Science B.V. All rights reserved.

Keywords: Capacity Enhancement, Swollen Chitosan Beads, Color Removal, Tyrosinase Immobilization, Aqueous-Solutions, Chelating-Agents, Waste-Water, Adsorption, Sorption, Derivatives, Adsorbents, Sorbents, Kinetics, Phenols

? Thomsen, A.B. and Laturnus, F. (2001), The influence of different soil constituents on the reaction kinetics of wet oxidation of the creosote compound quinoline. Journal of Hazardous Materials, 81 (1-2), 193-203.

Full Text: 2001\J Haz Mat81, 193.pdf

Abstract: Creosote contaminated sites have become a widespread problem in industrialized countries. Recently, wet oxidation using high temperature, pressure, water and oxygen followed by activated sludge treatment proved to be an efficient method for removing a wide selection of creosote compounds in contaminated soils. Wet oxidation of the creosote compound quinoline was carried out in the presence of montmorillionite, quartz and humic acid. The products derived from wet oxidation were identified and treated biologically by activated sludge testing their biodegradability. The influence on the oxidation kinetics, of quinoline during wet oxidation was pH dependent. Humic acid supported the oxidation of quinoline, whereas the addition of montmorillionite and quartz had either an inhibiting effect or led only to a slight increase in oxidation. In mixtures of soil constituents, especially at low contents of humic acid, the adsorption of quinoline on montmorillionite prevented oxidation at neutral pH. Thus, alkaline extraction of both quinoline and humic acid was needed for an efficient oxidation. A proposed reaction mechanism suggests that quinoline was oxidized by hydroxyl radicals formed during the oxidation of the humic acid. A wide selection of reaction products (mainly carboxylic acids, benzene and pyridine derivatives) derived from the wet oxidation of humic acid and quinoline. The reaction products from humic acid degradation had a rate limiting effect on the wet oxidation of quinoline leaving small residues of quinoline after the treatment. On the contrary, these reaction products also improved the biodegradation of products from the quinoline oxidation due to co-digestion of carboxylic acids. Therefore, the presence of soil components (mainly humic acid) improved the combined wet oxidation and biological activated sludge treatment of quinoline. (C) 2001 Elsevier Science B.V. All rights reserved.

Keywords: Acid, Acids, Activated Sludge, Adsorption, Air Oxidation, Aqueous-Solution, Benzene, Biodegradability, Biodegradation, Carboxylic Acids, Contaminated Soils, Degradation, Extraction, Humic, Humic Acid, Hydroxyl, Hydroxyl Radicals, Kinetics, Low, Mechanism, Mixtures, Model, Organic-Compounds, Oxidation, Oxidation Kinetics, Oxygen, pH, Phenol, Pressure, Products, Quartz, Quinoline, Radicals, Rate Limiting, Reaction, Reaction Kinetics, Reaction Mechanism, Residues, Selection, Sites, Sludge, Soil, Soils, Sorption, Temperature, Testing, Treatment, Water, Wet Oxidation

? Jackman, A.P., Kennedy, V.C. and Bhatia, N. (2001), Interparticle migration of metal cations in stream sediments as a factor in toxics transport. Journal of Hazardous Materials, 82 (1), 27-41.

Full Text: 2001\J Haz Mat82, 27.pdf

Abstract: Sorption of metal cations by stream sediments is an important process affecting the movement of released contaminants in the environment. The ability of cations to desorb from one sediment particle and subsequently sorb to another can greatly affect metal transport rates but rates for this process have not been reported. The objective of this study was to determine the rate at which sorbed metals can migrate from contaminated sediment particles to uncontaminated sediment particles as a function of the concentration of the contaminating solution and the duration of the contact with the contaminating solution. Samples of small sediment particles were exposed to solutions containing cobalt, after which they were rinsed and combined with larger uncontaminated sediment particles in the presence of stream water. Initial concentrations of the contaminating solution ranged from 1 ng/l to 1000 mg/l and exposures to the contaminating solution ranged from 6 h to 14 days, The rate of the migration increased with increasing concentrations in the contaminating solution and with decreasing times of exposure to the contaminating solution. Under the conditions of these experiments, the time required for the migration to reach equilibrium was on the order of months or longer. In separate experiments, the kinetics of adsorption and desorption of cobalt were measured as a function of concentration of the contaminating solution. The time required to reach adsorption equilibrium increased with increasing concentration in the contaminating solution, Times to sorption equilibrium were on the order of months. Desorption was much slower than adsorption and, together with intraparticle diffusion, probably controls the rate of migration from contaminated to uncontaminated sediment. The results of this study show that interparticle migration of metal cations can proceed at significant rates that are strongly influenced by the length of time that the metal has been in contact with the sediment. (C) 2001 Elsevier Science B.V. All rights reserved.

Keywords: Ability, Adsorption, Adsorption Equilibrium, Affect, Cadmium, Cations, Cd, Cobalt, Contact, Contaminants, Desorption, Diffusion, Environment, Equilibrium, Exchange, Experiments, Exposure, Function, Heavy Metals, Intraparticle Diffusion, Kaolinite, Kinetics, Kinetics, Kinetics of Adsorption, Metal, Metals, Migration, Model, Presence, Process, Ray-Absorption Spectroscopy, Rights, Sediment, Sediments, Sorption, Sorption, Surface Complexes, Transport, Water

? Cabbar, H.C. and Bostanci, A. (2001), Moisture effect on the transport of organic vapors in sand. Journal of Hazardous Materials, 82 (3), 313-322.

Full Text: 2001\J Haz Mat82, 313.pdf

Abstract: Vapor-phase affects the transport, lifetime, and fate of volatile organic contaminants in soils. Furthermore, it has an effect on the assessment and the selection of a remediation approach. The diffusion of dichloromethane (DCM), 1,1,1-trichloroethane (TCE) and carbon tetrachloride (CTC) in dry and wet sand media were investigated using a packed column at room temperature. The apparent diffusion coefficients, D_app, which accounts for effective diffusion and sorption of DCM, TCE and CTC were determined by fitting the experimental data to a diffusion model. The apparent diffusion coefficients of DCM, TCE and CTC for wet sand were found to be larger than the corresponding values for dry sand. The presence of water reduced retardation factors expressed in terms of the sorption capacity for each compound. The results indicated that dry mineral surface provided dominant sorption sites. This is reflected in greater amounts of organic vapors adsorbed under dry conditions. On the other hand, lower sorption capacities for organic compounds on vapor-water interface than on vapor-mineral interface and their low solubilities resulted in smaller retardation factors in wet sand. The experiments clearly demonstrate the role of humidity in sorption and transport of vapors in sand. (C) 2001 Elsevier Science B.V. All rights reserved.

Keywords: Assessment, Capacity, Carbon, Column, Contaminants, Diffusion, Diffusion Coefficients, Experiments, Factors, Fitting, Humidity, Lifetime, Media, Model, Moist Soil, Organic Compounds, Organic Contaminants, Packed Column, Presence, Remediation, Retardation Factor, Rights, Sand, Selection, Soil, Soils, Sorption, Sorption Capacity, Sorption In Soil, Surface, TCE, Temperature, Transport, Transport of Organic Vapors, Unsaturated Zone, Values, Water

? Li, K., Santilli, A., Goldthorp, M., Whiticar, S., Lambert, P. and Fingas, M. (2001), Solvent vapour monitoring in work space by solid phase micro extraction. Journal of Hazardous Materials, 83 (1-2), 83-91.

Full Text: 2001\J Haz Mat83, 83.pdf

Abstract: Solid phase micro extraction (SPME) is a fast, solvent-less alternative to conventional charcoal tube sampling/carbon disulfide extraction for volatile organic compounds (VOC). In this work, SPME was compared to the active sampling technique in a typical lab atmosphere. Two different types of fibre coatings were evaluated for solvent vapour at ambient concentration. A general purpose 100 mum film polydimethylsiloxane (PDMS) fibre was found to be unsuitable for VOC work, despite the thick coating. The mixed-phase carboxen/PDMS fibre was found to be suitable. Sensitivity of the SPME was far greater than charcoal sorbent tube method. Calibration studies using typical solvent such as dichloromethane (DCM), benzene (B) and toluene (T) showed an optimal exposure time of 5 min, with a repeatability of less than 20% for a broad spectrum of organic vapour. Minimum detectable amount for DCM is in the range of 0.01 mug/l (0.003 ppmv). Variation among different fibres was generally within 30% at a vapour concentration of 1 mug DCM/l, which was more than adequate for field monitoring purpose. Adsorption characteristics and calibration procedures were studied. An actual application of SPME was carried out to measure background level of solvent vapour at a bench where DCM was used extensively, Agreement between the SPME and the charcoal sampling method was generally within a factor of two. No DCM concentration was found to be above the regulatory limit of 50 ppmv. (C) 2001 Published by Elsevier Science B.V.

Keywords: Adsorption, Air Monitoring, Background, Benzene, Charcoal Sorbent, Coating, Exposure, Extraction, Film, Monitoring, Organic Compounds, Solvent Vapour Analysis, Sorbent, Space, SPME, Technique, Toluene, VOC, Volatile Organic Compounds, Work

? Schweigkofler, M. and Niessner, R. (2001), Removal of siloxanes in biogases. Journal of Hazardous Materials, 83 (3), 183-196.

Full Text: 2001\J Haz Mat83, 183.pdf

Abstract: Methods for the removal of gaseous silicon compounds in biogases are presented. In laboratory studies, various solid adsorption materials and liquid absorption solutions were evaluated for their siloxane elimination efficiencies. Among the liquid sorbents studied, concentrated nitric acid and sulfuric acid were found to be especially potent siloxane removing agents at elevated temperature. Solid adsorbents tested include activated charcoal, carbopack B, Tenax TA, XAD II resins, molecular sieve 13X and silica gel. Apart from activated charcoal, silica gel showed especially high adsorption capacities of more than 100 mg/g for siloxanes. Furthermore, excellent thermal regeneration of the loaded material was possible. The efficiency of silica gel in removing gaseous siloxanes was verified at a sewage treatment plant, where an adsorption bed with silica gel was used for biogas drying. Other gas pretreatment installations studied included refrigeration condensers and adsorbent beds of meadow ore for the catalytic removal of hydrogen sulfide. In contrast to biogas drying by refrigeration, which had a poor effect on siloxane content, the installation of meadow ore adsorption beds resulted in a significant siloxane reduction of 31-75%, depending on the site studied. (C) 2001 Elsevier Science B.V. All rights reserved.

Keywords: 13x, Acid, Activated Charcoal, Adsorbent, Adsorbents, Adsorption, Adsorption Capacities, Degradation, Efficiency, Gas Pretreatment, Gel, Hydrogen Sulfide, Landfill Gas, Pretreatment, Reduction, Regeneration, Removal, Resins, Rights, Sewage, Sewage Gas, Silica, Silica Gel, Siloxanes, Sorbents, TA, Temperature, Treatment

? Miller, T.C. and Holcombe, J.A. (2001), Comparison and evaluation of the synthetic biopolymer poly-L-aspartic acid and the synthetic “plastic” polymer poly-acrylic acid for use in metal ion-exchange systems. Journal of Hazardous Materials, 83 (3), 219-236.

Full Text: 2001\J Haz Mat83, 219.pdf

Abstract: Poly-L-aspartic acid (PLAsp), a biopolymer, and a similar synthetic polymer, poly-acrylic acid (PAA), each consisting of similar to 50 repeating Asp and acrylic acid monomers, respectively, were immobilized onto controlled pore glass (CPG) and evaluated for use as metal ion-exchange materials. Both polymers achieve metal complexation primarily through their repeating carboxylate side groups resulting in a similar binding trend for the metals tested (Ca²⁺, Cd²⁺, Co²⁺, Cu²⁺ Mg²⁺, Mn²⁺, Na⁺, Ni²⁺, Pb²⁺), With metal binding capacities ranging from <0.1 to 12 mu mol metal/g column and <0.1 to 32 mu mol metal/g column for PLAsp and PAA respectively. Cu2+ and Pb2+ exhibited strong binding to both materials, while the other metals demonstrated only weak or minimal binding. Both columns allowed for quantitative release of bound metals through acid stripping and experienced increased overall metal binding with increasing pH. Both systems also maintained similar structural and chemical stability when continuously exposed to neutral buffered, highly acidic, oxidizing, large molecule rich, and elevated temperature environments. The main differences between the two systems are the material cost and system biodegradability. (C) 2001 Elsevier Science B.V. All rights reserved.

Keywords: Acid, Biodegradability, Cd²⁺, Co²⁺, Column, Comparison, Complexation, Controlled Pore Glass, Cost, Cu²⁺, Evaluation, Immobilized Poly(L-Cysteine), Ion Exchange, Ion-Exchange, Metal, Metal Binding, Metals, Microfiltration Membranes, Ni²⁺, PAA, Pb²⁺, pH, Poly-Acrylic Acid, Poly-L-Aspartic Acid, Polymer, Quantitative, Rights, Silica-Gels, Sorption, Stability, Systems, Temperature

de Heredia, J.B., Torregrosa, J., Dominguez, J.R. and Peres, J.A. (2001), Oxidation of p-hydroxybenzoic acid by UV radiation and by TiO₂/UV radiation: Comparison and modelling of reaction kinetic. Journal of Hazardous Materials, 83 (3), 255-264.

Full Text: J\J Haz Mat83, 255.pdf

Abstract: The phenolic compound p-hydroxybenzoic acid is very common in a great variety of agroindustrial wastewaters (olive oil and table olive industries, distilleries). The objective of this work was to study the photocatalytic activity of TiO₂ towards the decomposition of p-hydroxybenzoic acid. In order to demonstrate the greater oxidizing power of the photocatalytic system and to quantify the additional levels of degradation attained, we performed experiments on the oxidation of p-hydroxybenzoic acid by UV radiation alone and by the TiO₂/UV radiation combination. A kinetic model is applied for the photooxidation by UV radiation and by the TiO₂/UV system. Experimental results indicated that the kinetics for both oxidation processes can be fitted well by a pseudo-first-order kinetic model. The second oxidation process can be explained in terms of the Langmuir–Hinshelwood kinetic model. The values of the adsorption equilibrium constant, K_pHB, and the second order kinetic rate constant, k_c, were 0.37ppm⁻¹ and 6.99ppmmin⁻¹, respectively. Finally, a comparison between the kinetic rate constants for two oxidation systems reveals that the constants for the TiO₂/UV system are clearly greater (between 220–435%) than those obtained in the direct UV photooxidation.

Keywords: Adsorption, Adsorption Equilibrium, Comparison, Decomposition, Degradation, Equilibrium, Experiments, Kinetic, Kinetic Model, Kinetics, Model, Modelling, Oxidation, P-Hydroxybenzoic Acid, Photocatalysis, Photocatalytic Activity, Power, Pseudo First Order, Pseudo-First-Order, Radiation, Rate Constant, Rate Constants, Second Order, Second-Order, Systems, TiO₂, Titanium Dioxide, UV, UV Radiation, Wastewaters, Work

Yu, B., Zhang, Y., Shukla, A., Shukla, S.S. and Dorris, K.L. (2001), The removal of heavy metals from aqueous solutions by sawdust adsorption: Removal of lead and comparison of its adsorption with copper. Journal of Hazardous Materials, 84 (1), 83-94.

Full Text: J\J Haz Mat84, 83.pdf

Abstract: In this work sorption of lead on sawdust (SD) has been studied by using batch techniques. Similar to the sorption of copper, the equilibrium sorption levels for lead is a function of the solution pH, contact time, sorbent and sorbate concentration. The equilibrium adsorption capacity of sawdust for lead was measured and extrapolated using Linear Freundlich and Langmuir isotherms and compared with that for copper. Metal ions which are bounded to the sawdust could be stripped by acidic solution so that the sawdust can be recycled. Non-equilibrium experiments were done by using glass columns. The results indicate the potentially practical value of this method in industries and also provide strong evidence to support the adsorption mechanism proposed. Even though the focus of this work is on lead, some results from previous study for copper have been incorporated here for sake of comparison. (C) 2001 Published by Elsevier Science B.V. All rights reserved.

Keywords: Sawdust, Metal Ions, Lead, Adsorption, Wastewater, Carbon

? Shen, Z.M., Wang, W.H., Jia, J.P., Ye, J.C., Feng, X. and Peng, A. (2001), Degradation of dye solution by an activated carbon fiber electrode electrolysis system. Journal of Hazardous Materials, 84 (1), 107-116.

Full Text: 2001\J Haz Mat84, 107.pdf

Abstract: Degradation of 29 dyes by means of an activated carbon fiber (ACF) electrode electrolysis system was performed successfully. Almost all dye solutions tested were decolorized effectively in this ACF electrolysis process. Internal relationships between treatment mechanisms and chemical composition of the dye have been discussed in this paper. Generally, it is shown that higher solubility leads to greater degradation in the process. Dyes with many -SO₃-, COO-, -SO₂NH₂, -OH, hydrophilic groups, and azo Linkages are susceptible to reduction. However, dyes with many -C=O, -NH- and aromatic groups, and hydrophobic groups, tend to be adsorbed. For dyes with -SO₃-, -COOH and -OH groups, if their molecules linearly spread in solution and have a significant tendency to form colloids by hydrogenous bonding, they also tend to be adsorbed and flocculated. Typical dynamic electrolysis of dye Acid Red B, Vat Blue BO and Disperse Red E-4B shows how the two major mechanisms, degradation and adsorption, act differently during treatment. Reduction occurs evenly during treatment. During the dominant adsorption process, after certain amount of iron is generated, colloid precipitation occurs and TOC and color are rapidly removed. (C) 2001 Elsevier Science B.V. All rights reserved.

Keywords: ACF, Activated Carbon, Activated Carbon Fiber, Adsorption, Adsorption Process, Carbon, Composition, Degradation, Dye, Dyes, Dynamic, Electrochemical Disinfection, Electrode, Electrolysis, Hydrophilic, Hydrophobic, Iron, NO, OH, Oxidation, Precipitation, Process, Reduction, Relationships, Rights, Spread, Temperature, TOC, Treatment, Treatment Mechanisms, Waste-Water, Wastewater

? Tekrony, M.C. and Ahlert, R.C. (2001), Adsorption of chlorinated hydrocarbon vapors onto soil in the presence of water. Journal of Hazardous Materials,