Personal Research Database

Full Text: W\Wat Res35, 3876.pdf

Abstract: The sorption of copper and cadmium ions onto bone char in single component systems has been studied using fixed-bed column adsorbers. The effects of solution flowrate, initial metal ion concentration and bone char particle size have been studied. A film-pore diffusion model has been developed to predict the fixed-bed breakthrough curves for the two metal ions. A sensitivity analysis has been carried out to investigate the influence of the external mass transfer coefficient (film resistance), the effective diffusion coefficient (pore diffusion) and the solid phase loading capacity. It is round that under the experimental conditions employed in the study, film diffusional resistance was tow and the Biot numbers were relatively high. Furthermore. a constant effective pore diffusivity was not sufficient to correlate the breakthrough curves accurately and a variable dependent effective diffusivity was required; suggesting a possible contribution front surface diffusion. Since the metal ion-bone char systems take a long time to reach equilibrium. the solid phase loading capacity as predicted by the ‘best-fit’ equilibrium isotherm. was not Suitable for use in the diffusional mass transport model and the mass balance solid phase loading was utilised instead. (C) 2001 Elsevier Science Ltd. All rights reserved.

Keywords: Adsorption Column, Metal Ions, Bone Char, Film-Pore Diffusion, Sorption, Activated Carbon Columns, Impregnated Macroporous Resins, Intraparticle Mass-Transport, Multicomponent Adsorption, Water-Purification, Binary Adsorption, Fluidized-Beds, Metal Sorption, Lead Removal, Batch Tests

Naseem, R. and Tahir, S.S. (2001), Removal of Pb(II) from aqueous/acidic solutions by using bentonite as an adsorbent. Water Research, 35 (16), 3982-3986.

Full Text: W\Wat Res35, 3982.pdf

Abstract: The ability of bentonite clay to remove Pb(II) from aqueous solutions and from nitric acid, hydrochloric acid and perchloric acid solutions (1.0 . 1×10^-5) has been studied at different optimized conditions of concentrations. amount of adsorbent, temperature, concentration of electrolyte and pH. Maximum adsorption of Pb(II), i.e. > 98% has been achieved in aqueous solutions, while 86% is achieved from 1.0×10^-5 M HCl using 0.5 g of bentonite. The adsorption decreases by increasing the concentration of electrolytes. Flame atomic absorption spectrometer was used for measuring lead concentration. Isotherm analysis of adsorption data obtained at 25°C, 30°C, 40°C and 50°C showed that the adsorption pattern of lead on bentonite followed the Langmuir isotherm and Freundlich isotherm. respectively. H° and S° were calculated from the slope and intercept of 1n K-D vs. I/T plots. (C) 2001 Elsevier Science Ltd. All rights reserved.

Keywords: Lead, Adsorption, Isotherms, Bentonite, Electrolytes, Thermodynamics, Adsorption Behavior, Lead

Notes: highly cited

Gupta, V.K., Shrivastava, A.K. and Jain, N. (2001), Biosorption of chromium(VI) from aqueous solutions by green algae Spirogyra species. Water Research, 35 (17), 4079-4085.

Full Text: W\Wat Res35, 4079.pdf

Abstract: Biosorption of heavy metals is an effective technology for the treatment of industrial wastewaters. Results are presented showing the sorption of Cr(VI) from solutions by biomass of filamentous algae Spirogyra species. Batch experiments were conducted to determine the adsorption properties of the biomass and it was observed that the adsorption capacity of the biomass strongly depends on equilibrium pH. Equilibrium isotherms were also obtained and maximum removal of Cr(VI) was around 14.7×10³ mg metal/kg of dry weight biomass at a pH of 2.0 in 120 min with 5 mg/l of initial concentration. The results indicated that the biomass of Spirogyra species is suitable for the development of efficient biosorbent for the removal and recovery of Cr(VI) from wastewater. (C) 2001 Elsevier Science Ltd. All rights reserved.

Keywords: Biosorption, Adsorption, Biosorbent, Algae, Wastewater, Heavy-Metal Biosorption, Saccharomyces-Cerevisiae, Azolla-Filiculoides, Cadmium Uptake, Marine-Algae, Waste-Water, Removal, Biomass, Recovery, Lead

Chern, J.M. and Wu, C.Y. (2001), Desorption of dye from activated carbon beds: Effects of temperature, pH, and alcohol. Water Research, 35 (17), 4159-4165.

Full Text: W\Wat Res35, 4159.pdf

Abstract: The adsorption isotherms of yellow and red dye solutions onto granular activated carbon at varying solution pHs (2-8), temperatures (15-50 degreesC), and alcohol concentrations (0 20%) were experimentally determined by batch tests and the Tóth model was found to best fit the adsorption isotherm data for varying solution pHs, temperatures, and alcohol concentrations. The maximum adsorption capacity was found to decrease with increasing solution pH and alcohol concentration and could be predicted by the correlation equations obtained in this study. A correlation equation was also obtained to account for the effects of solution temperature on the adsorption equilibrium constant. The 25 degreesC water was found to be a very poor regenerant for the carbon bed presaturated with the yellow dye compared with 20% alcohol solution. A simple equation was derived, based on non-linear wave propagation theory, to predict the desorption curves of activated carbon bed. Given presaturation concentration, bed density and void fraction, and adsorption isotherm, the wave propagation theory predicted the desorption curves quite satisfactorily. (C) 2001 Elsevier Science Ltd. All rights reserved.

Keywords: Dye Wastewater, Activated Carbon, Adsorption Isotherm, Desorption Curve, Wave Theory, Wave Propagation Theory, Fixed-Beds, Acid Dyes, Adsorption, Removal

Mohamed, Z.A. (2001), Removal of cadmium and manganese by a non-toxic strain of the freshwater cyanobacterium Gloeothece magna. Water Research, 35 (18), 4405-4409.

Full Text: W\Wat Res35, 4405.pdf

Abstract: The ability of both living and dry cells of Gloeothece magna, a non-toxic freshwater cyanobacterium, to adsorb cadmium and manganese is demonstrated in this study. Chlorophyll a content of living cells was not influenced by either cadmium or manganese concentrations, indicating that adsorption of both Cd²⁺ and Mn²⁺ by living cells of G. magna, was independent of the metabolic state of the organism. Moreover, the adsorption of both Cd²⁺ and Mn²⁺ to living cells and dry cells, was dependent on the metal concentrations, and fitted the Freundlich adsorption isotherm. However, dry cells had larger binding capacity for both Cd²⁺ (K_f = 912.6) and Mn²⁺ (K_f = 2398) than living cells (K_f = 151.4 & 63, respectively). The role of the capsular polysaccharides, the main constituents of the cyanobacterial envelope, in binding these two metals was also studied. Polysaccharide extracts of this organism adsorbed high amounts of both Cd²⁺ (115-425 µg mg^-1) and Mn²⁺ (473-906 µg mg^-1). This study suggests that G. magna would probably be cultured in water bodies contaminated by heavy metals to ameliorate their toxicity. Also dry material of this cyanobacterium being a non-toxic species, could be used as a safe biofilter to remove toxic metals from drinking water. (C) 2001 Elsevier Science Ltd. All rights reserved.

Keywords: Heavy Metals, Biosorption, Cyanobacteria, Gloeothece Magna, Polysaccharides, Neurospora-Crassa, Metal-Ions, Biosorption, Biomass, Accumulation, Polysaccharides

Tse, K.K.C. and Lo, S.L. (2002), Desorption kinetics of PCP-contaminated soil: Effect of temperature. Water Research, 36 (1), 284-290.

Full Text: W\Wat Res36, 248.pdf

Abstract: A thermally enhanced pump-and-treatment method for pentachlorophenol (PCP)-contaminated soil and ground-water has shown potential advantages over the traditional pump-and-treatment method. Studies on the desorption kinetics of PCP from aquifer soil are the first step toward quantitative assessment of the newly proposed method. Five series of desorption batch tests were conducted at different temperatures, and the test results were analyzed by linear regression to determine the best-fit kinetic model for PCP desorbed from the contaminated field soil under all temperature conditions. The first-order kinetic model, parabolic diffusion model. and modified Freundlich model were discussed in linear regression work. A modified Freundlich model was found to describe the PCP desorption kinetics from soil in consideration of a temperature effect. (C) 2001 Elsevier Science Ltd. All rights reserved.

Keywords: PCP, Thermal Desorption Kinetics, Steam Injection, Thermally Enhanced Pump-And-Treatment, Adsorption, Behavior

Wang, W.J., Wang, W.H., Zhang, X.L. and Wang, D.H. (2002), Adsorption of p-chlorophenol by biofilm components. Water Research, 36 (3), 551-560.

Full Text: W\Wat Res36, 551.pdf

Abstract: Through batch equilibrium experiments under the conditions of temperature 25 °C, pH values of 2.7, 5.3 and 6.1, the p-chlorophenol (4-cp) adsorption to biofilm components was investigated in this study. The contributions of biofilm components to 4-cp adsorption were discussed by comparing four adsorption systems, i.e. 4-cp adsorbed by model suspended particulate matter (kaolin) with biofilm coating, bacteria, bacterial exopolysaccharide (EPS) and kaolin, respectively. Langmuir and Freundlich isotherm equations were used to evaluate the experiment data. All the four adsorptions fitted for the two equations. Equilibrium isotherms were obtained for 4-cp adsorption on different adsorbents. The kinetic characteristics of 4-cp adsorption by biofilm components and the effect of pH on the kinetic process were investigated. The time to reach the highest adsorption amount and near equilibrium state in the four systems was different. The 4-cp adsorption by kaolin with biofilm coating reached near equilibrium at 60 min at pH 6.1. The 4-cp adsorption by EPS and kaolin reached near equilibrium at 150 and 180 min, respectively. But the 4-cp adsorption by bacteria showed no evident near equilibrium during 3 h in the experiment. The impact of pH value on the adsorption was also examined. The adsorption amount slightly increased with increasing pH from 2.7 to 6.1 for the adsorption systems of bacterial EPS and kaolin, but it slightly decreased in the systems of kaolin with biofilm coating and bacteria. (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Biofilm, 4-CP, Bacteria, Exopolysaccharide, Kaolin, Adsorption

Sotelo, J.L., Ovejero, G., Delgado, J.A. and Martínez, I. (2002), Comparison of adsorption equilibrium and kinetics of four chlorinated organics from water onto GAC. Water Research, 36 (3), 599-608.

Full Text: W\Wat Res36, 599.pdf

Abstract: This study deals with the adsorption of four chlorinated pollutants onto GAC (F-400); two pesticides (lindane and alachlor) and two PCB congeners: 2-PCB (MPCB) and 2,2’,5,5’-PCB (TPCB). Equilibrium and kinetic parameters have been obtained for the adsorption of alachlor and each PCB, whereas the kinetic results for lindane presented elsewhere (Proc. First World Water Congr. Int. Water Assoc., Texts of Posters, CD-ROM, AGHTM, Paris, 2000) are reanalyzed in this work. A model assuming a bidisperse structure (macro- and micropores), each region having a different adsorption isotherm, is used to study the adsorption kinetics in a batch system in the period dominated by macropore diffusion. Both the saturation capacity and the rate of internal transport of TPCB are much lower than those of the other solutes. This difference is attributed to a chemisorption mechanism for this compound, which is favored by its very low solubility. (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Alachlor, PCB, Activated Carbon, Adsorption

Chakravarty, S., Dureja, V., Bhattacharyya, G., Maity, S. and Bhattacharjee, S. (2002), Removal of arsenic from groundwater using low cost ferruginous manganese ore. Water Research, 36 (3), 625-632.

Full Text: W\Wat Res36, 625.pdf

Abstract: A low cost ferruginous manganese ore (FMO) has been studied for the removal of arsenic from groundwater. The major mineral phases present in the FMO are pyrolusite and goethite. The studied FMO can adsorb both AS(III) and As(V) without any pre-treatment, adsorption of As(III) being stronger than that of As(V). Both As(III) and As(V) are adsorbed by the FMO in the pH range of 2–8. Once adsorbed, arsenic does not get desorbed even on varying the pH in the range of 2–8. Presence of bivalent cations, namely, Ni²⁺, Co²⁺, Mg²⁺ enhances the adsorption capability of the FMO. The FMO has been successfully used for the removal of arsenic from six real groundwater samples containing arsenic in the range of 0.04–0.18ppm. Arsenic removals are almost 100% in all the cases. The cost of the FMO is about 50–56 US$ per metric tonne. (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Ferruginous Manganese Ore, Arsenic Removal, Groundwater

Chern, J.M. and Chien, Y.W. (2002), Adsorption of nitrophenol onto activated carbon: Isotherms and breakthrough curves. Water Research, 36 (3), 647-655.

Full Text: W\Wat Res36, 647.pdf

Abstract: The adsorption isotherm of p-nitrophenol onto granular activated carbon in 25°C aqueous solution was experimentally determined by batch tests. Both the Freundlich and the Redlich-Peterson models were found to fit the adsorption isotherm data well. A series of column tests were performed to determine the breakthrough curves with varying bed depths (3–6cm) and water flow rates (21.6–86.4cm³/h). Explicit equations for the breakthrough curves of the fixed-bed adsorption processes with the Langmuir and the Freundlich adsorption isotherms were developed by the constant-pattern wave approach using a constant driving force model in the liquid phase. The results show that the half breakthrough time increases proportionally with increasing bed depth but decreases inverse proportionally with increasing water flow rate. The constant-pattern wave approach using the Freundlich isotherm model fits the experimental breakthrough curves quite satisfactorily. A correlation was proposed to predict the volumetric mass-transfer coefficient in the liquid phase successfully. The effects of solution temperature and pH on the adsorption isotherm were also studied and the Tóth model was found to fit the isotherm data well at varying solution temperatures and pHs. (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Activated Carbon, Adsorption, Adsorption Isotherm, Adsorption Isotherms, Aqueous-Solution, Breakthrough, Breakthrough Curve, Breakthrough Curves, Degradation, Dye Adsorption, Fixed Bed, Fixed-Bed Adsorption, Flow Rate, Kinetics, Langmuir, Model, P-Nitrophenol, P-Nitrophenol, Removal, Substituted Phenols, Wave Propagation Theory, Wave Theory

Zhao, X., Höll, W.H. and Yun G. (2002), Elimination of cadmium trace contaminations from drinking water. Water Research, 36 (4), 851-858.

Full Text: W\Wat Res36, 851.pdf

Abstract: Raw waters polluted with trace heavy metals present serious problems to the part of the Chinese water supply. One of the important contaminants is cadmium. Removal of trace amounts of heavy metals can be achieved by means of selective sorption processes. One of the possibilities is the application of weak base anion exchangers. LEWIS-base; acid interactions lead to an exclusive sorption of heavy metal cations and an equivalent amount of anions of strong acids. The respective elimination of cadmium from pure solutions and spiked natural water and the regeneration of the exhausted exchanger has been investigated. The results demonstrate a very efficient elimination. The standards for drinking water are met for a very large relative volume of treated water. In addition, even a considerable share of dissolved organic matter is adsorbed. Regeneration requires a first step with sulfuric acid to remove the metals and a second one with sodium hydroxide to neutralize the exchanger and to displace the DOC adsorbed. The heavy metals can be concentrated in a small volume which facilitates the discharge of the waste. (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Cadmium, Weakly Basic Exchange Resin, Drinking Water

Solisio, C., Lodi, A., Converti, A. and Borghi, M.D. (2002), Removal of exhausted oils by adsorption on mixed Ca and Mg oxides. Water Research, 36 (4), 899-904.

Full Text: W\Wat Res36, 899.pdf

Abstract: Adsorption tests were performed on two different exhausted oils to reduce their polluting and health hazard potential: a ‘water-insoluble oil’, utilised for automotive engine lubrication, and an ‘emulsified’ oil, used as coolant for metal-cutting tools. Dolomite, a low-cost recovery material, was used to prepare two effective adsorbents: (a) a mixed Ca and Mg oxide obtained by thermal decomposition of dolomite at 1800°C, and (b) an activated material obtained by submitting this product to chemical treatment with HCl. Preliminary tests carried out with an excess of the former material showed that the insoluble oil was adsorbed with lower yield (Y=0.40) than the soluble (emulsified) oil (Y=0.60). The material activation with HCl remarkably improved the adsorption of soluble oil organic fraction (Y>0.90), while only a little increase in the removal yield was observed for the insoluble oil (Y=0.44). The results presented and discussed in this work pointed out that the products of dolomite calcination can successfully replace the conventional adsorbing materials in the removal of organic pollutants, with particular concern to exhausted soluble oils, which cannot usually be recycled, thus reducing the operational costs of their treatment. (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Emulsified Oil, Insoluble Oil, Adsorption, Mixed Ca and Mg Oxide, Pollutants Removal

Notes: highly cited

? Esplugas, S., Giménez, J., Contreras, S., Pascual, E. and Rodríguez, M. (2002), Comparison of different advanced oxidation processes for phenol degradation. Water Research, 36 (4), 1034-1042.

Full Text: 2002\Wat Res36, 1034.pdf

Abstract: Advanced Oxidation Processes (O₃, O₃/H₂O₂, UV, UV/O₃, UV/H₂O₂, O₃/UV/H₂O₂, Fe²⁺/H₂O₂ and photocatalysis) for degradation of phenol in aqueous solution have been studied in earlier works. In this paper, a comparison of these techniques is undertaken: pH influence, kinetic constants, stoichiometric coefficient and optimum oxidant/pollutant ratio. Of the tested processes, Fenton reagent was found to the fastest one for phenol degradation. However, lower costs were obtained with ozonation. In the ozone combinations, the best results were achieved with single ozonation. As for the UV processes, UV/H₂O₂ showed the highest degradation rate.

Keywords: Phenol, Ozone, UV radiation, Hydrogen Peroxide, Fenton, Photocatalysis

Shen, Y.H. (2002), Removal of phenol from water by adsorption–flocculation using organobentonite. Water Research, 36 (5), 1107-1114.

Full Text: W\Wat Res36, 1107.pdf

Abstract: Bentonite modified with short chain cationic surfactant might be the basis of a new approach to removing organic pollutants from water. The treatment process involves dispersing bentonite to the contaminated water and then adding a small cationic surfactant so as to result in flocs which are agglomerates of organobentonite and bound organic pollutants. The flocs are then removed from the solution by sedimentation. Experimental results indicate that BTMA-bentonite displays a high affinity for phenol, possibly because phenol molecules interact favorably with the benzene ring in BTMA ion through increased – type interactions. Under appropriate operating conditions, 90% phenol removal and nearly 100% bentonite recovery could be achieved by the adsorption–flocculation process using BTMA-bentonite. Additionally, the insensitivity of the process to the changing ionic strength of the solution and rapid adsorption kinetics made adsorption–flocculation with BTMA-bentonite attractive for continuous treatment of large volumes of industrial wastewater. The bentonite may function as a recyclable surfactant support for the adsorption and subsequent combustion of organic pollutants.

Keywords: Organobentonite, Adsorption, Flocculation, Phenol

Bai, R.S. and Abraham, T.E. (2002), Studies on enhancement of Cr(VI) biosorption by chemically modified biomass of Rhizopus nigricans. Water Research, 36 (5), 1224-1236.

Full Text: W\Wat Res36, 1224.pdf

Abstract: This study reports the biosorption of Cr(VI) by chemically modified biomass of Rhizopus nigricans and the possible mechanism of Cr complexation to the adsorbent. The cell wall of this fungus possesses strong complexing property to effectively remove Cr(VI) anions from solution and wastewater. The mechanism of Cr adsorption by R. nigricans was ascertained by chemical modifications of the dead biomass followed by FTIR spectroscopic analysis of the cell wall constituents. Treatment of the biosorbent with mild alkalies (0.01 N NaOH and ammonia solution) and formaldehyde (10%, w/v) deteriorated the biosorption efficiency. However, extraction of the biomass powder in acids (0.1N HCl and H₂SO₄), alcohols (50% v/v, CH₃OH and C₂H₅OH) and acetone (50%, v/v) improved the Cr uptake capacity. Reaction of the cell wall amino groups with acetic anhydride reduced the biosorption potential drastically. Blocking of the –COOH groups by treatment with water soluble carbodiimide also resulted in initial lag in Cr binding. Biomass modification experiments conducted using Cetyl Trimethyl Ammonium Bromide (CTAB), Polyethylenimine (PEI), and Amino Propyl Trimethoxy Silane (APTS) improved the biosorption efficiency to exceptionally high levels. The FTIR spectroscopic analysis of the native, Cr bound and the other types of chemically modified biomass indicated the involvement of amino groups of Rhizopus cell wall in Cr binding. The adsorption data of the native and the most effectively modified biomass were evaluated by the Freundlich and the Langmuir adsorption isotherms and the possible adsorption phenomena are also discussed. (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Biosorption, Chemical Modification, Heavy Metals, Rhizopus nigricans, Binding Sites, FTIR Spectroscopy, Hexavalent Chromium

Gin, K.Y.H., Tang, Y.Z. and Aziz, M.A. (2002), Derivation and application of a new model for heavy metal biosorption by algae. Water Research, 36 (5), 1313-1323.

Full Text: W\Wat Res36, 1313.pdf

Abstract: An equilibrium model for describing the relationships between important parameters for heavy metal sorption by algae was derived through a thermodynamics approach. In this model, both the removal efficiency of heavy metal and metal adsorption per unit algal biomass are considered to be simple functions of the ratio of algal biomass concentration to the initial metal concentration for selected conditions, i.e. as at constant pH and temperature. The model was found to fit the experimental results well (judged by the correlation–regression coefficient, R²), for the adsorption of cadmium, copper, lead and zinc by two algal species, Oocystis sp. (both living and non-living) and Chlorococcum sp. The applicability of the model was also supported by the reprocessed results of experimental data given in the literature, i.e. for the metal species, Cd, Pb, Cu and Ag, the algal species, Chlorella vulgaris, Scenedesmus quadricauda and Cladophora crispata, and both batch and continuous fixed-bed reactors. It was also demonstrated that the model could be applied over a broad range of pH for cadmium and copper adsorption by Oocystis sp. However, the model was not applicable at very low and high pH levels, due to negligible adsorption and precipitation, respectively. (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Heavy Metal, Biosorption, Algal Biomass, Equilibrium Model, Cadmium (Cd), Copper (Cu)

? Jiang, J.Q. and Lloyd, B. (2002), Progress in the development and use of ferrate(VI) salt as an oxidant and coagulant for water and wastewater treatment. Water Research,