Personal Research Database

Full Text: 2004\Wat Res38, 3881.pdf

Abstract: Soil-chemical contact time (aging) is an important determinant of the sorption and desorption characteristics of the organic contaminants and pesticides in the environment. The effects of aging on mechanism-specific sorption and desorption of atrazine were studied in soil and clay slurries. Sorption isotherm and desorption kinetic experiments were performed, and soil-water distribution coefficients and desorption rate parameters were evaluated using linear and nonlinear sorption equations and a three-site desorption model, respectively. Aging time for sorption of atrazine in sterilized soil and clay slurries ranged from 2 days to 8 months. Atrazine sorption isotherms were nearly linear (r(2)>0.97) and sorption coefficients were strongly correlated to soil organic carbon content. Sorption distribution coefficients (K-d) increased with increase in age in all five soils studied, but not for K-montmorillonite. Sorption non-linearity did not increase with increase in age except for the Houghton muck soil. Desorption profiles were well described by the three-site desorption model. The equilibrium site fraction (f(eq)) decreased and the non-desorbable site fraction (f(nd)) increased as a function of aging time in all soils. For K-montmorillonite, f(nd) approximate to 0 regardless of aging, showing that aging phenomena are sorbent/mechanism specific. In all soils, it was found that when normalized to soil organic matter content, the concentration of atrazine in desorbable sites was relatively constant, whereas that in non-desorbable site increased. This, and the lack of aging effects on desorption from montmorillonite, suggests that sorption into nondesorbable sites of soil organic matter is primary source of increased atrazine sorption in soils during aging. (C) 2004 Elsevier Ltd. All rights reserved.

Keywords: Adsorption-Desorption, Aging, Atrazine, Clay, Desorption, Desorption-Kinetics, Diffusion-Model, Distributed Reactivity Model, Distribution Coefficients, Environment, Equilibrium, Isotherm, Isotherms, Kinetics, Model, Montmorillonite, Natural Sediments, Phase-Distribution, Polychlorinated-Biphenyls, Primary, Slow Desorption, Soil, Sorption, Sorption, Sorption Isotherm, Time

Notes: highly cited

? Singh, K.P., Malik, A., Mohan, D. and Sinha, S. (2004), Multivariate statistical techniques for the evaluation of spatial and temporal variations in water quality of Gomti River (India) - a case study. Water Research, 38 (18), 3980-3992.

Full Text: 2004\Wat Res38, 3980.pdf

Abstract: This case study reports different multivariate statistical techniques applied for evaluation of temporal/spatial variations and interpretation of a large complex water-quality data set obtained during monitoring of Gomti River in Northern part of India. Water quality of the Gomti River, a major tributary of the Ganga River was monitored at eight different sites selected in relatively low, moderate and high pollution regions, regularly over a period of 5 years (1994-1998) for 24 parameters. The complex data matrix (17,790 observations) was treated with different multivariate techniques such as cluster analysis, factor analysis/principal component analysis (FA/PCA) and discriminant analysis (DA). Cluster analysis (CA) showed good results rendering three different groups of similarity between the sampling sites reflecting the different water-quality parameters of the river system. FA/PCA identified six factors, which are responsible for the data structure explaining 71% of the total variance of the data set and allowed to group the selected parameters according to common features as well as to evaluate the incidence of each group on the overall variation in water quality. However, significant data reduction was not achieved, as it needed 14 parameters to explain 71% of both the temporal and spatial changes in water quality. Discriminant analysis showed the best results for data reduction and pattern recognition during both temporal and spatial analysis. Discriminant analysis showed five parameters (pH, temperature, conductivity, total alkalinity and magnesium) affording more than 88% right assignations in temporal analysis, while nine parameters (pH, temperature, alkalinity, Ca-hardness, DO, BOD, chloride, sulfate and TKN) to afford 91% right assignations in spatial analysis of three different regions in the basin. Thus, DA allowed reduction in dimensionality of the large data set, delineating a few indicator parameters responsible for large variations in water quality. This study presents necessity and usefulness of multivariate statistical techniques for evaluation and interpretation of large complex data sets with a view to get better information about the water quality and design of monitoring network for effective management of water resources. (C) 2004 Elsevier Ltd. All rights reserved.

Keywords: Gomti River, Water Quality, Multivariate Techniques, Cluster Analysis, Factor Analysis, Principal Component, Discriminant Analysis, Principal Component Analysis, Fecal Pollution, Phosphorus, Nitrogen

Badruzzaman, M., Westerhoff, P. and Knappe, D.R.U. (2004), Intraparticle diffusion and adsorption of arsenate onto granular ferric hydroxide (GFH). Water Research, 38 (18), 4002-4012.

Full Text: W\Wat Res38, 4002.pdf

Abstract: Porous iron oxides are being evaluated and selected for arsenic removal in potable water systems. Granular ferric hydroxide, a typical porous iron adsorbent, is commercially available and frequently considered in evaluation of arsenic removal methods. GFH is a highly porous (micropore volume 0.0394±0.0056 cm³ g⁻¹, mesopore volume 0.0995±0.0096 cm³ g⁻¹) adsorbent with a BET surface area of 235±8 m² g⁻¹. The purpose of this paper is to quantify arsenate adsorption kinetics on GFH and to determine if intraparticle diffusion is a rate-limiting step for arsenic removal in packed-bed treatment systems. Data from bottle-point isotherm and differential column batch reactor (DCBR) experiments were used to estimate Freundlich isotherm parameters (K and 1/n) as well as kinetic parameters describing mass transfer resistances due to film diffusion (k_f) and intraparticle surface diffusion (D_s). The pseudo-equilibrium (18 days of contact time) arsenate adsorption density at pH 7 was 8 μg As/mg dry GFH at a liquid phase arsenate concentration of 10 μg As/L. The homogeneous surface diffusion model (HSDM) was used to describe the DCBR data. A non-linear relationship (D_S=3.0⁻⁹×R_p^1.4) was observed between D_s and GFH particle radius (R_P) with D_s values ranging from 2.98×10⁻¹² cm² s⁻¹ for the smallest GFH mesh size (100×140) to 64×10⁻¹¹ cm² s⁻¹ for the largest GFH mesh size (10×30). The rate-limiting process of intraparticle surface diffusion for arsenate adsorption by porous iron oxides appears analogous to organic compound adsorption by activated carbon despite differences in adsorption mechanisms (inner-sphere complexes for As versus hydrophobic interactions for organic contaminants). The findings are discussed in the context of intraparticle surface diffusion affecting packed-bed treatment system design and application of rapid small-scale column tests (RSSCTs) to simulate the performance of pilot- or full-scale systems at the bench-scale.

Keywords: Arsenic, Iron, Adsorption, Surface Diffusion, Water Treatment

Yang, J., Jia, J.P., Liao, J. and Wang, Y.L. (2004), Removal of fulvic acid from water electrochemically using active carbon fiber electrode. Water Research, 38 (19), 4353-4360.

Full Text: W\Wat Res38, 4353.pdf

Abstract: Humic acids (HA) are a group of widely existing natural organic compounds and potential contaminants to underground water reservoirs. Fulvic acid (FA) is a typical humic acid of relatively low molecular weight. Electrochemical removal of FA from water by active carbon fiber (ACF) electrodes was studied by using light scattering photometer (LSP), fluorescence spectroscopy and total organic carbon analyzer (TOC). The experiments showed that FA molecules aggregated and that the average particle diameter in FA solution increased from below 10 nm to hundreds of nanometers during the treatment process. When iron was added to the anode, the FA could be coagulated efficiently at the early stage of the treatment. The proposed mechanism of the removal process is: adsorption of FA on ACF surface→aggregation of FA→desorption of FA aggregates from ACF→coagulation of FA aggregates by nFe(OH)₂.mFe(OH)₃ dissolved from anode. Experiments were also repeated using graphite and stainless-steel electrodes, and the results were compared with that of ACF electrodes. FA aggregation was not observed in these experiments and most FA was not removed from the solution. At the end of this paper, FA samples from Huai River sediment were successfully treated using the ACF electrode.

Keywords: Active Carbon Fiber, Fulvic Acid, Electro-Chemistry, Light Scattering Photometer, Wastewater, Fluorescence Spectroscopy

? Quan, M., Liu, X.T., Bo, L.L., Chen, S., Zhao, Y.Z. and Cui, X.Y. (2004), Regeneration of acid orange 7-exhausted granular activated carbons with microwave irradiation. Water Research, 38 (20), 4484-4490.

Full Text: 2004\Wat Res38, 4484.pdf

Abstract: An investigation was performed for the regeneration of three granular activated carbons (GACs) exhausted with acid orange 7 (AO7). The three GACs were made from different materials, i.e. coconut shells, almond nucleus and coal. The AO7 adsorption process was carried out in a continuous-flow adsorption column. After adsorption, the AO7-saturated GAC was dried at 120degreesC, then regenerated in a quartz reactor by 2450MHz microwave (MW) irradiation at 850W for 5 min. The efficacy of this procedure was analyzed by determining the rates and amounts of AO7 adsorbed in successive adsorption-MW regeneration cycles. Effects of this regeneration on the structural properties, surface chemistry and the AO7 adsorption capacities of GAC samples were examined. It was found that after several adsorption-MW regeneration cycles, the adsorption rates and capacities of GACs could maintain relatively high levels, even higher than those of virgin GACs, as indicated by AO7 breakthrough curves and adsorption isotherms. The improvement of GAC adsorption properties resulted from the modification of pore size distribution and surface chemistry by MW irradiation. (C) 2004 Elsevier Ltd. All rights reserved.

Keywords: Acid Orange 7, Activated Carbon, Adsorption, Adsorption, Adsorption Isotherms, Breakthrough Curves, Decomposition, Dye, High-Pressure, Liquid Water, Microwave Irradiation, Regeneration, Temperature

Egirani, D. (2005), Comments on: Removal of copper ions from aqueous solution by tree ferns. Water Research, 38 (20), 4535.

Full Text: W\Wat Res38, 4535.pdf

Ho, Y.S. (2005), Erratum to ‘Removal of copper ions from aqueous solution by tree fern’: [Water Res. 37 (2003) 2323–2330]. Water Research, 38 (20), 4536-4537.

Full Text: W\Wat Res38, 4536.pdf, W\Wat Res-Ho2.pdf

Notes: highly cited

? Clara, M., Kreuzinger, N., Strenn, B., Gans, O. and Kroiss, H. (2005), The solids retention time - a suitable design parameter to evaluate the capacity of wastewater treatment plants to remove micropollutants. Water Research, 39 (1), 97-106.

Full Text: 2005\Wat Res39, 97.pdf

Abstract: Micropollutants as endocrine disrupting compounds (EDC) or pharmaceuticals are of increased interest in water pollution control. Wastewater treatment plant (WWTP) effluents are relevant point sources for residues of these compounds in the aquatic environment. The solids retention time (SRT) is one important parameter for the design of WWTPs, relating to growth rate of microorganisms and to effluent concentrations. If a specific substance is degraded in dependency on the SRT, a critical value for the sludge age can be determined. In WWTPs operating SRTs below this critical value, effluent concentrations in the range of influent concentrations or a distribution according to the adsorption equilibrium have to be expected, whereas in WWTPs operating at SRTs higher than the critical value degradation will occur. Critical SRTs were determined for different micropollutants, indicating that the design criteria based on the sludge age allows an estimation of emissions. Different treatment technologies as conventional activated sludge systems and a membrane bioreactor were considered and no significant differences in the treatment efficiency were detected when operated at comparable SRT. The results of the investigations lead to the conclusion that low effluent concentrations can be achieved in WWTPs operating SRTs higher than 10 days (referred to a temperature of 10degreesC). This corresponds to the requirements for WWTPs situated in sensitive areas according to the urban wastewater directive of the European Community (91/271/EEC) in moderate climatic zones. (C) 2004 Elsevier Ltd. All rights reserved.

Keywords: Wastewater Treatment, Plant Design, Solids Retention Time, Removal Potential, Endocrine Disrupting Compounds, Pharmaceuticals, Hazardous Substances, Sewage-Treatment Plants, Municipal Sewage, Activated-Sludge, Bisphenol-A, Pharmaceutical Residues, Estrogens, Fate, Environment, Behavior

Wang, S.B., Boyjoo, Y., Choueib, A. and Zhu, Z.H. (2005), Removal of dyes from aqueous solution using fly ash and red mud. Water Research, 39 (1), 129-138.

Full Text: W\Wat Res39, 129.pdf

Abstract: Fly ash and red mud have been employed as adsorbents for the removal of a typical basic dye, Methylene blue, from aqueous solution. Heat treatment and chemical treatment have also been applied to the as-received fly ash and red mud samples. It is found that fly ash generally shows higher adsorption capacity than red mud. The raw fly ash and red mud show adsorption capacity at 1.4×10⁻⁵ and 7.8×10⁻⁶ mol/g, respectively. Heat treatment reduces the adsorption capacity for both fly ash and red mud but acid treatment by HNO₃ induces a different effect on fly ash and red mud. Nitric acid treatment results in an increase in adsorption capacity of fly ash (2.4×10⁻⁵ mol/g) while it decreases the adsorption capacity for red mud (3.2×10⁻⁶ mol/g). The adsorption data have been analysed using Langmuir, Freundlich and Redlich–Peterson isotherms. The results indicate that the Redlich–Peterson model provides the best correlation of the experimental data. Isotherms have also been used to obtain the thermodynamic parameters such as free energy, enthalpy and entropy of adsorption. For fly ash and red mud, adsorption of Methylene blue is endothermic reaction with ΔH⁰ at 76.1 and 10.8 kJ/mol, respectively.

Keywords: Fly Ash, Red Mud, Basic Dyes, Wastewater, Adsorption

Diniz, V. and Volesky, B. (2005), Biosorption of La, Eu and Yb using Sargassum biomass. Water Research, 39 (1), 239-247.

Full Text: W\Wat Res39, 239.pdf

Abstract: Biosorption of the lanthanides: Lanthanum (La³⁺), Europium (Eu³⁺) and Ytterbium (Yb³⁺) from single-component and multi-component batch systems using Sargassum polycystum Ca-loaded biomass was studied. The ion exchange sorption mechanism was confirmed by the release of calcium ions from the biomass that matched the total number of metal and protons removed from the solution. The metal binding increased with pH due to the decrease of proton concentration in the system, as they also compete for the binding sites. The maximum metal uptake capacity for pH 3, 4 and 5 ranged approximately between (0.8–0.9) mmol g⁻¹ for La (0.8–0.9) mmol g⁻¹ for Eu, and (0.7–0.9) mmol g⁻¹ for Yb. Biosorption from multi-component mixtures was examined at pH 4 using equimolar initial concentrations of the metals. The metal affinity sequence established was Eu>La>Yb, and the maximum metal uptake obtained was 0.29, 0.41, 0.28 mmol g⁻¹ for La, Eu and Yb, respectively.

Keywords: Biosorption, Ion Exchange, Lanthanum, Europium, Ytterbium, Sargassum

Zheng, S.K., Yang, Z.F., Jo, D.H., Park, Y.H. and Ho, Y.S. (2005), Comment on ‘Removal of chlorophenols from groundwater by chitosan sorption’. Water Research, 39 (1), 264-268.

Full Text: W\Wat Res39, 264.pdf, W\Wat Res-Ho3.pdf

Keywords: Fungus Aspergillus-Niger, Sugarcane Bagasse Pith, Heavy-Metal Adsorption, Activated Date Pits, Sphagnum Moss Peat, Aqueous-Solution, Kinetic-Models, Tree Fern, Dye Sorption, Cadmium Ion

Zheng, S.K. and Yang, Z.F. (2005), Reply to comment on originality of kinetic models by Y.-S. Ho. Water Research, 39 (1), 269.

Full Text: W\Wat Res39, 269.pdf

Zhang, F.S., Nriagu, J.O. and Itoh, H. (2005), Mercury removal from water using activated carbons derived from organic sewage sludge. Water Research, 39 (2-3), 389-395.

Full Text: W\Wat Res39, 389.pdf

Abstract: Various types of activated carbons were developed from organic sewage sludge (SS) using H₂SO₄, H₃PO₄ and ZnCl₂ as chemical activation reagents, and the removal of Hg(II) from aqueous solution by these carbons was effectively demonstrated. The quality of the activated carbons was dramatically improved owing to chemical activation. ZnCl₂ activated carbon had the highest capability for Hg(II) adsorption, followed by H₃PO₄ and H₂SO₄ activated carbons. The adsorption was greatly affected by Hg(II) concentration, solution pH and carbon dosage, and followed Lagergren first order rate equation and Freundlich isotherm model. Desorption results indicated that around 60% to 80% of the adsorbed Hg(II) could be recovered from the carbons to 0.1 M HNO₃ solution by sonication treatment. Accordingly, it is believed that the activated carbons developed in this study are effective and practical for utilization in industrial wastewater treatment for mercury removal.

Keywords: Mercury, Activated carbon, Sewage sludge, Adsorption, Wastewater, Desorption

Benkli, Y.E., Can, M.F., Turan, M. and Çelik, M.S. (2005), Modification of organo-zeolite surface for the removal of reactive azo dyes in fixed-bed reactors. Water Research, 39 (2-3), 487-493.

Full Text: W\Wat Res39, 487.pdf

Abstract: Modification of zeolite (clinoptilolite) surface with a quaternary amine, hexadecyl trimethyl ammonium bromide (HTAB), to improve the removal efficiency of reactive azo dyes in a zeolite fixed bed was investigated. A series of adsorption tests were conducted to find out the uptake of three types of reactive dyes, i.e. CI Reactive Black 5, Red 239 and Yellow 176. Each run consisted of modifying zeolite with HTAB in the column followed by removal of color from the modified zeolite bed. The breakthrough curves for modification process were constructed under different conditions by plotting the normalized effluent concentration (C/C₀) versus time or bed volumes (BV). Optimization studies show that 3 g/l of HTAB dosage at a flowrate of 0.025 l/min showed the best performance. Examination of the dye removal under the optimum modification conditions reveals that the black dye gives the highest breakthrough point among the three dyes tested. This is ascribed to the hydrophobic/hydrophilic match of the zeolite surface with the dye molecule, which depends upon the way zeolite is modified with HTAB. Calculations of the HTAB coverage on zeolite surface indicate that a bilayer formation is the most viable packing that enables maximum removal of the dye.

Keywords: Activated Carbon, Adsorption, Adsorption, Ammonia Removal, Behavior, Breakthrough Curves, Clinoptilolite, Clinoptilolite, Color Removal, Decolorization, Drinking-Water, Dye, Dyes, Fixed Bed, HTAB, Reactive Dyes, Removal, Textile Effluents

Park, D., Yun, Y.S., Jo, J.H. and Park, J.M. (2005), Mechanism of hexavalent chromium removal by dead fungal biomass of Aspergillus niger. Water Research, 39 (4), 533-540.

Full Text: W\Wat Res39, 533.pdf

Abstract: When synthetic wastewater containing Cr(VI) was placed in contact with the dead fungal biomass of Aspergillus niger, the Cr(VI) was completely removed from aqueous solution, whereas Cr(III), which was not initially present, appeared in aqueous solution. Desorption and X-ray photoelectron spectroscopy (XPS) studies showed that most of the Cr bound on the biomass was in trivalent form. These results indicated that the main mechanism of Cr(VI) removal was a redox reaction between Cr(VI) and the dead fungal biomass, which is quite different from previously reported mechanisms. The influences of contact time, pH, Cr(VI) concentration, biomass concentration and temperature on Cr(VI) removal were also evaluated. The Cr(VI) removal rate increased with a decrease in pH and with increases in Cr(VI) concentration, biomass concentration and temperature. Although removal kinetics was dependent on the experimental conditions, Cr(VI) was completely removed in the aqueous solution. In conclusion, a new mechanism of Cr(VI) removal by the dead fungal biomass has been proposed. From a practical viewpoint, this abundant and inexpensive dead fungal biomass has potential application in the conversion of toxic Cr(VI) into less toxic or nontoxic Cr(III).

Keywords: Biosorption, Hexavalent Chromium, Fungi, Reduction, Detoxification

James, G., Sabatini, D.A., Chiou, C.T., Rutherford, D., Scott, A.C. and Karapanagioti, H.K. (2005), Evaluating phenanthrene sorption on various wood chars. Water Research, 39 (4), 549-558.

Full Text: W\Wat Res39, 549.pdf

Abstract: A certain amount of wood char or soot in a soil or sediment sample may cause the sorption of organic compounds to deviate significantly from the linear partitioning commonly observed with soil organic matter (SOM). Laboratory produced and field wood chars have been obtained and analyzed for their sorption isotherms of a model solute (phenanthrene) from water solution. The uptake capacities and nonlinear sorption effects with the laboratory wood chars are similar to those with the field wood chars. For phenanthrene aqueous concentrations of 1 μgl⁻¹, the organic carbon-normalized sorption coefficients (log K_oc) ranging from 5.0 to 6.4 for field chars and 5.4–7.3 for laboratory wood chars, which is consistent with literature values (5.6–7.1). Data with artificial chars suggest that the variation in sorption potential can be attributed to heating temperature and starting material, and both the quantity and heterogeneity of surface-area impacts the sorption capacity. These results thus help to corroborate and explain the range of log K_oc values reported in previous research for aquifer materials containing wood chars.

Keywords: Wood Char, Sorption, K_oc, Phenanthrene, Nonlinear Isotherms, Surface Area

Li, Y.H., Di, Z.C., Ding, J., Wu, D.H., Luan, Z.K. and Zhu, Y.Q. (2005), Adsorption thermodynamic, kinetic and desorption studies of Pb²⁺ on carbon nanotubes. Water Research, 39 (4), 605-609.

Full Text: W\Wat Res39, 605.pdf

Abstract: Adsorption thermodynamics of Pb²⁺ on carbon nanotubes has been studied at various temperatures of 280, 298 and 321 K and the thermodynamic parameters, such as equilibrium constant (K₀), standard free energy changes (ΔG°), standard enthalpy change (ΔH°) and standard entropy change (ΔS°), have been obtained. A pseudo-second-order rate model has been employed to describe the kinetic adsorption processes. Desorption studies reveal that Pb²⁺ can be easily removed from carbon nanotubes by altering the pH values of the solution using both HCl and HNO₃, indicating that carbon nanotubes are a promising absorbent for wastewater treatment.

Keywords: Adsorption, Carbon Nanotubes, Desorption, Kinetics, Lead, Thermodynamics

Wu, R.C., Qu, J.H. and Chen, Y.S. (2005), Magnetic powder MnO–Fe₂O₃ composite: A novel material for the removal of azo-dye from water. Water Research,