Personal Research Database

Full Text: W\Wat Res34, 4270.pdf

Abstract: Six different species of non-living Sargassum biomass were compared on the basis of their equilibrium Cd and Cu uptake in order to evaluate potential variability in the sorption performance of different Sargassum species. Biosorption uptakes for Cd at the optimal pH of 4.5 ranged from q_max = 0.90 mmol/g for Sargassum sp. 1 to 0.66 mmol/g for S. filipendula I representing a 36% difference. Three species were evaluated for their Cu uptake where q_max = 0.93 mmol/g for S. vulgare; 0.89 mmol/g for S. filipendula I, and 0.80 for S. fluitans, representing a 16% difference between the lowest and highest values. Potentiometric titrations were carried out on S. vulgare, S. fluitans and S. filipendula I and yielded the similar results of 1.5 mmol/g weakly acidic sites for S. vulgare and S. fluitans, and 1.6 mmol/g for S. filipendula I. Estimates of 0.3 mmol/g of strongly acidic sites for S. fluitans and S. filipendula I and 0.5 mmol/g for S. vulgare were obtained. The total number of active sites averaged 1.9±0.1 mmol/g. The elution efficiency for Cu-desorption from S. filipendula was determined for CaCl₂, Ca(NO₃)₂, and HCl at various concentrations and solid: liquid ratios (S/L). The highest elution efficiency was >95% for Cu for all elutants at S/L=1 g/l and decreased for both calcium salts with increasing S/L to less than 50% at S/L=10 g/l as a new batch sorption equilibrium was reached quickly. CaCl₂ was chosen to be the most suitable metal-cation desorbing agent.

Keywords: Biosorption, Sargassum, Metals, Heavy Metals, Metal Removal, Desorption

Notes: highly cited

Al-Qodah, Z. (2000), Adsorption of dyes using shale oil ash. Water Research, 34 (17), 4295-4303.

Full Text: W\Wat Res34, 4295.pdf

Abstract: The adsorption of reactive dyes on shale oil ash has been investigated during a series of batch adsorption experiments. The adsorption isotherm data were fitted to Langmuir isotherm. The two-resistance mass transfer model has been developed based on the film resistance and homogeneous solid phase diffusion.

A computer program has been developed to estimate the theoretical concentration-lime dependent curves and to compare them with the experimental curves by means of the best-fit approach. The model predicts that the external mass transfer coefficient K was not affected by varying the initial dye concentration, but it increases when the agitation speed and temperature was raised. The diffusion coefficient D was Found to increase when the initial dye concentration, and temperature was raised. (C) 2000 Elsevier Science Ltd. Ail rights reserved.

Keywords: Adsorption Kinetics, Adsorption Modeling, Industrial Wastewater Treatment, Reactive Dyes, Shale Oil Ash, Adsorbents, External Mass-Transfer, Aqueous-Solutions, Activated Carbon, Color Removal, Waste-Water, Fly-Ash, Dyestuffs, Particles, Wood

Othman, M.Z., Roddick, F.A. and Hobday, M.D. (2000), Evaluation of Victorian low rank coal-based adsorbents for the removal of organic compounds from aqueous systems. Water Research, 34 (18), 4351-4358.

Full Text: W\Wat Res34, 4351.pdf

Abstract: Three activated carbons and two chars made from low rank coal were evaluated in terms of their ability to remove the organic compound 4-nitrophenol (4-NP) and natural organic matter (NOM) from aqueous systems. The adsorption equilibrium capacities of all adsorbents for 4-NP correlated with the micropore area of the adsorbents. Adsorption rates showed improved removal with decreasing particle size and higher carbon mass loadings. A pseudo first order model was used to fit the kinetic data, with a correlation coefficient of 0.995-0.999 for all systems.

The adsorption capacity for NOM, as measured by UV-absorbing DOG, correlated well with the pore volume and pore surface areas for pores with diameters in the range 2.7-21 nm. The trend in the adsorption capacities and removal rates of the adsorbents for NOM provided evidence that the pore size distribution is one of the most important physical characteristics of activated carbon for the adsorption of NOM.

The performance of activated low rank coal based materials was comparable to a high quality coconut-based commercial carbon in batch systems. Although the non-activated char adsorbents gave poor performance, they have potential for use in applications where poor performance can be outweighed by lower cost. (C) 2000 Elsevier Science Ltd. All rights reserved.

Keywords: Adsorption, Activated Carbon, 4-Nitrophenol, Adsorption Kinetics, DOC, NOM, Activated Carbon Adsorption, Humic Substances, GAC, Matter, Size

Gupta, V.K. and Ali, I. (2001), Removal of DDD and DDDE from wastewater using bagasse fly ash, a sugar industry waste. Water Research, 35 (1), 33-40.

Full Text: W\Wat Res35, 33.pdf

Abstract: Bagasse fly ash, a waste from the sugar industry, was converted into an effective adsorbent and was used for the removal of DDD [2,2-Bis(4-chlorophenyl)1,1-dichloroethane] and DDE [2,2-Bis(4-chlorophenyl)-1,1-dichloroethene] pesticides from wastewater. The DDD and DDE are removed by the developed adsorbent up to 93% at pH 7.0, with the adsorbent dose of 5 g/l of particle size 200-250 µm at 30 degreesC. The removal of these two pesticides was achieved up to 97-98% in column experiments at a flow rate of 0.5 ml/min. The adsorption was found to be exothermic in nature. The bagasse fly ash system has been used for the removal of DDD and DDE from the wastewater. The developed system is very useful, economic, and reproducible. (C) 2000 Elsevier Science Ltd. All rights reserved.

Keywords: Adsorption, Bagasse Fly Ash, DDD, DDE, Low-Cost Adsorbent, Earth Elements, Water, Adsorption, Pesticides, Cadmium, Chromatography, Equilibrium, Oxides

Ebie, K., Li, F.S., Azuma, Y., Yuasa, A. and Hagishita, T. (2001), Pore distribution effect of activated carbon in adsorbing organic micropollutants from natural water. Water Research, 35 (1), 167-179.

Full Text: W\Wat Res35, 167.pdf

Abstract: Adsorption isotherms of organic micropollutants in coexistence with natural organic matter (NOM) were analyzed to evaluate the impacts of pore size distribution of activated carbon (AC) on the competition effects of the NOM. Single solute adsorption experiments and simultaneous adsorption experiments with NOM contained in a coagulation-pretreated surface water were performed for four agricultural chemicals and three coal-based activated carbons (ACs) having different pore distributions. The results showed that, for all the carbons used, the adsorption capacity of the chemicals was reduced distinctly in the presence of NOM. Such a reduction was more apparent for AC with a larger portion of small pores suitable for the adsorption of small organic molecules and for the agricultural chemicals with a more hydrophilic nature. Ideal adsorbed solution theory (IAST) incorporated with the Freundlich isotherm expression (IAST-Freundlich model) could not interpret the impact of NOM on the adsorption capacity of the chemicals unless a pore blockage effect caused by the adsorption of NOM was also considered. By taking into account this effect, the adsorption isotherm of the chemicals in the presence of NOM was well described, and the capacity reduction caused by the NOM was quantitatively assessed from the viewpoints of the site competition and the pore blockage. Analytical results clearly indicated that pore blockage was an important competition mechanism that contributed to 10-99% of the total capacity reductions of the chemicals, the level depended greatly on the ACs, the chemicals and the equilibrium concentrations, and could possibly be alleviated by broadening the pore size distributions of the ACs to provide a large volume percentage for pores with sizes above 30 Angstrom. (C) 2001 Elsevier Science Ltd. All rights reserved.

Keywords: Activated Carbon, Pore Size Distribution, Site Competition, Pore Blockage, Agricultural Chemicals, Natural Organic Matter, Humic Substances, Adsorption, Size, Fibers, Acids

Shubha, K.P., Raji, C. and Anirudhan, T.S. (2001), Immobilization of heavy metals from aqueous solutions using polyacrylamide grafted hydrous tin(IV) oxide gel having carboxylate functional groups. Water Research, 35 (1), 300-310.

Full Text: W\Wat Res35, 300.pdf

Abstract: A new adsorbent containing a carboxylate group has been prepared by the surface modification of a polyacrylamide grafted hydrous tin(IV) oxide gel. The product exhibits a very high adsorption potential for Pb(II), Hg(II) and Cd(II). The effect of initial metal ion concentration, adsorbent dose pH concentration of light metal ions, and temperature on metal removal has been studied. The process follows a first-order rate kinetics. The intraparticle diffusion of metal ions through pores in the adsorbent was shown to be the main rate limiting step. The equilibrium data fit well with the Langmuir adsorption isotherm. The selectivity order of the adsorbent is Pb(II) > Hg(II) > Cd(II). Adsorption rate constants and thermodynamic parameters were also presented to predict the nature of adsorption. The method was applied on synthetic wastewaters. Acid regeneration has been tried for several cycles with a view to recover the adsorbed metal ions and also to restore the sorbent to its original state. (C) 2000 Elsevier Science Ltd. All rights reserved.

Keywords: Polymer Grafted Metal Oxide, Metal Removal and Recovery, Adsorption Isotherm, Thermodynamic Parameters, Wastewater, Bituminous Coal, Silica-Gel, Adsorption, Sorption, Ions, Desorption, Water

Mier, M.V., Callejas, R.L., Gehr, R., Cisneros, B.E.J. and Alvarez, P.J.J. (2001), Heavy metal removal with Mexican clinoptilolite: Multi-component ionic exchange. Water Research, 35 (2), 373-378.

Full Text: W\Wat Res35, 373.pdf

Abstract: This paper describes the interactions of Pb(II), Cd(II), and Cr(VI) competing for ion-exchange sites in naturally occurring clinoptilolite. Dissolved Pb and Cd were effectively removed within Ish in batch reactors, with higher removal efficiencies (> 95%) in the acidic pH range. The presence of Cr(VI); which can interact with these metals to form anionic complexes, significantly diminished the Pb and Cd removal efficiencies. A decrease in the efficiency of clinoptilolite to remove Pb was also observed in the high (greater than or equal to 10) pH range. This was attributed to the formation of anionic hydroxo-complexes with little affinity for cationic ion exchange sites. Pb outcompeted Cd for ion exchange sites in a flow-through column packed with clinoptilolite (contact time = 10 s). The preferential removal of Pb in column, but not in batch reactors, reflects that competitive retention can be affected by contact time because diffusion kinetics may influence the removal efficiency to a greater extent than equilibrium partitioning. Phenol, which was tested as a representative organic co-contaminant, slightly hindered heavy metal removal in batch reactors. This was attributed to the formation of organometallic complexes that cannot penetrate the zeolite exchange channels. Altogether, these results show that natural zeolites hold great potential to remove cationic heavy metal species from industrial wastewater. Nevertheless, process efficiency can be hindered by the presence of ligands that form complexes with reduced accessibility and/or affinity for ion exchange. (C) 2000 Elsevier Science Ltd. All rights reserved.

Keywords: Cadmium, Chromium, Lead, Phenol, pH, Zeolite, Clinoptilolite, Natural Sedimentary, Adsorption, Zeolites, Capacity, Models, Design

Talarposhti, A.M., Donnelly, T. and Anderson, G.K. (2001), Colour removal from a simulated dye wastewater using a two-phase anaerobic packed bed reactor. Water Research, 35 (2), 425-432.

Full Text: W\Wat Res35, 425.pdf

Abstract: In recent years, rapid technological advances in the textile and dyeing industry have yielded benefits to society but have also generated new and significant environmental problems. The treatment alternatives applicable for the removal of colour vary, depending upon the type of dye wastewater. A synthetic, simulated mixed dye waste (Basic Yellow 28, Basic Yellow 21, Basic Red 18.1, Basic Violet Red 16, Basic Red 46, Basic Blue 16, Basic Blue 41) representing a known waste from a fibre production factory, was investigated. The biological process of anaerobic digestion has been recognised as a simple and energy-efficient means of treating and stabilising a wide range of organic industrial wastewaters. This study sets out to demonstrate the effect of different loading rates, dye concentrations and hydraulic retention times (HRTs) on colour removal efficiency under mesophilic anaerobic conditions. The reactor was operated under mesophilic conditions at different organic loading rates (OLRs) and HRTs for nine months. The results of this study show that a 2-stage mesophilic anaerobic up-flow packed bed reactor can remove up to 90% of the colour from a mixed cationic dye containing 1000 mg/l of dye. Colour removal efficiency falls as the influent dye concentration increases, but rises with increased hydraulic retention time and increased organic loading. The primary colour removal mechanism was one of biosorption with subsequent biodegradation. Acetoclastic methanogens were moderately inhibited at low organic loading rates of 0.25 kg COD/m³d, at which level, acidogenesis and acetogenesis appeared to be unaffected. Inhibition of acidogenesis became marked at higher OLRs (1 kg COD/m³d) and when the HRT was reduced from 5 to 3 days. (C) 2000 Elsevier Science Ltd. All rights reserved.

Keywords: Basic Dyes, Decolorisation, Anaerobic Packed Bed Reactor, Mesophilic Bacteria, Courtaulds Ltd

Quan, C., Khoe, G. and Bagster, D. (2001), Adsorption of sodium lauryl sulfate onto arsenic-bearing ferrihydrite. Water Research, 35 (2), 478-484.

Full Text: W\Wat Res35, 478.pdf

Abstract: Ferrihydrite is an excellent adsorbent for binding trace toxic contaminants such as arsenic, and precipitate flotation of the arsenic-bearing ferrihydrite has been studied. Anionic surfactants such as sodium lauryl sulfate (SLS) and sodium oleate (NaOL) are suitable collectors for the flotiition. The adsorption of SLS both alone and after the subsequent addition of NaOL on these precipitates at pH 4-5 was measured. It has been shown that the synergistic effect of the two surfactants on notation is dependent on their addition order. The presence of NaOL before SLS in the conditioning stage call prevent the adsorption of SLS because of the electrostatic shielding of adsorption sites on the precipitates. The post addition of NaOL to the SLS-bearing precipitates can promote the flocculation of the precipitates and enhance entrainment of SLS for better Rotation. The SLS adsorption data fit better with the modified Frumkin isotherm than the Langmuir isotherm. Thermodynamic parameters (-DeltaG(ads)degrees, DeltaH(ads)degrees, and DeltaS(ads)degrees) have been derived from the analysis of the adsorption isotherms. The results suggest that the adsorption of SLS on AFH is physical and exothermic. (C) 2000 Elsevier Science Ltd. Ali rights reserved

Keywords: Precipitate Flotation, Arsenic and Ferrihydrite, Sodium Lauryl Sulfate, Sodium Oleate, and Modified Frumkin Adsorption Isotherms, Flotation, Hydroxide, Removal, Surface

Nakano, Y., Takeshita, K. and Tsutsumi, T. (2001), Adsorption mechanism of hexavalent chromium by redox within condensed-tannin gel. Water Research, 35 (2), 496-500.

Full Text: W\Wat Res35, 496.pdf

Abstract: We have proposed a new recovery system of hexavalent chromium Cr(VI) that is of great toxicity utilizing condensed-tannin gels derived from a natural polymer with many polyhydroxyphenyl groups. The adsorption mechanism of Cr(VI) to the tannin molecules was clarified. The adsorption mechanism consists of four reaction steps; the esterification of chromate with tannin molecules, the reduction of Cr(VI) to trivalent chromium Cr(III), the formation of carboxyl group by the oxidation of tannin molecules and the ion exchange of the reduced Cr(III) with the carboxyl and hydroxyl groups. It was found in this recovery system that a large amount of proton was consumed accompanied with the reduction of Cr(VI) so that the acidic solution containing Cr(VI) was transferred automatically to neutral one by choosing an appropriate initial pH. The carboxyl group which was created by the oxidation of tannin molecules parallel to the reduction of Cr(VI) to Cr(III) contributed to an increase in the ion-exchange sites of the reduced Cr(III). The maximum adsorption capacity of Cr(VI) reached 287 mg Cr/g dry tannin gel under the conditions of 0.77 water content of tannin gel and the initial pH = 2. This adsorption capacity was five to ten times higher than that obtained by the ion exchange between ordinary Cr(III) and tannin molecules for the tannin gels prepared under similar conditions. The system proposed here will provide an important information on a zero-emission-oriented process because it has such advantages as higher adsorption capacity of chromium and lower volume of secondary wastes compared with conventional process. (C) 2000 Elsevier Science Ltd. All rights reserved

Keywords: Tannin, Gel, Hexavalent Chromium, Removal, Redox, Chromium, Plant Biomass, Removal

Martín-Gullón, I. and Font, R. (2001), Dynamic pesticide removal with activated carbon fibers. Water Research, 35 (2), 516-520.

Full Text: W\Wat Res35, 516.pdf

Abstract: Rapid small-scale minicolumn tests were carried out to simulate the atrazine adsorption in water phase with three palletized pitch-based activated carbon fibers (ACF) and one commercial granular activated carbon (GAC). Initial atrazine solutions were prepared with pretreated ground water. Minicolumn tests showed that the performance of highly activated carbon fibers (surface area of 1700 m²/g) is around 7 times better than the commercial GAC (with surface area at around 1100 m²/g), whereas carbon fibers with medium activation degree (surface area of 1500 m²/g) had a removal efficiency worse than the commercial carbon. The high removal efficiency of the highly activated ACF is due to the wide-opened microstructure of the material, with an appreciable contribution of the low size mesopores, maintaining at these conditions a fast kinetic adsorption rate rather than a selective adsorbent for micropollutants vs. natural organic matter. (C) 2000 Elsevier Science Ltd. All rights reserved

Keywords: Atrazine, Natural Organic Matter, Minicolumn, Pore Size Distribution, Adsorption, Water

Lee, S.M. and Davis, A.P. (2001), Removal of Cu(II) and Cd(II) from aqueous solution by seafood processing waste sludge. Water Research, 35 (2), 534-540.

Full Text: W\Wat Res35, 534.pdf

Abstract: Dried waste slurry generated in seafood processing factories has been shown to be an effective adsorbent for the removal of heavy metals from dilute solutions. Characterization of the sludge surface with scanning electron microscope and X-ray microanalyzer were carried out to evaluate the components on the sludge surface that are related to the adsorption of metal ions. Aluminum and calcium, as well as organic carbon are distributed on the surface of sludge. Alkalimetric titration was used to characterize the surface acidity of the sludge sample. The surface acidity constants, pK(a1)(s) and pK(a2)(s) were 5.50 and 9.55, respectively. Batch as well as dynamic adsorption studies were conducted with 10 to 510^-3 M Cu(II) and Cd(II). A surface complexation model with the diffuse layer model successfully predicted Cu(II) and Cd(II) removals in single metal solutions. Predictions of sorption in binary-adsorbate systems based on single-adsorbate data fits represented competitive sorption data reasonably well over a wide range of conditions. The breakthrough capacity found from column studies was different for each metal ion and the data reflect the order of metal affinity for the adsorbent material very well, (C) 2000 Elsevier Science Ltd. Ail rights reserved

Keywords: Adsorption, Seafood Processing Sludge, Surface Acidity, Heavy Metals, Copper, Cadmium, Sewage-Sludge, Heavy-Metals, Activated Carbon, Fly-Ash, Adsorption, Complexation, Acid, Cd, Cu, Zn

Notes: highly cited

Cheung, C.W., Porter, J.F. and McKay, G. (2001), Sorption kinetic analysis for the removal of cadmium ions from effluents using bone char. Water Research, 35 (3), 605-612.

Full Text: W\Wat Res35, 605.pdf

Abstract: The adsorption of cadmium ions onto bone char has been studied using a batch adsorber. The experimental data was analyzed using four sorption kinetic models-the pseudo-first order, the Ritchie second order, the modified second order and the Elovich equations-to determine the best fit equation for the sorption of metal ions onto bone char. The best-fit equation was identified using the sum of the errors squared (SSE). Finally, equilibrium studies were used to evaluate the sorption capacity of bone char for cadmium ions and experimental results showed this to be 0.57 mmol g^-1 at an equilibrium solution concentration of 3.0 mmol dm^-3. Since the sorption capacity is relatively high, bone char can be considered as a suitable sorbent for the adsorption of cadmium in wastewater treatment systems. (C) 2001 Elsevier Science Ltd. All rights reserved.

Keywords: Adsorption, Analysis, Batch, Bone Char, Cadmium, Cadmium Ions, Capacity, Carbon, Char, Copper, Elovich Equation, Equilibrium, Equilibrium Studies, Experimental, Kinetic, Kinetic Analysis, Langmuir-Freundlich Isotherm, Metal, Metal Ions, Modified Second Order Equation, Peat, Pseudo-First Order, Pseudo-First Order Equation, Pseudo-First-Order, Removal, Rights, Ritchie Second Order Equation, Second Order, Second-Order, Solution, Sorbent, Sorption, Sorption Capacity, Treatment, Waste-Water, Wastewater, Wastewater Treatment

Notes: highly cited

Wu, F.C., Tseng, R.L. and Juang, R.S. (2001), Kinetic modeling of liquid-phase adsorption of reactive dyes and metal ions on chitosan. Water Research, 35 (3), 613-618.

Full Text: W\Wat Res35, 613.pdf

Abstract: The rates of adsorption of three commercial reactive dyes and Cu(II) from water in the absence and presence of complexing agents using chitosan were measured at 30 degreesC. Three simplified kinetic models, i.e, pseudo-first-order, pseudo-second-order, and intraparticle diffusion, were tested to investigate the adsorption mechanisms. It was shown that the adsorption of reactive dyes and Cu(II) in the absence of complexing agents could be best described by the intraparticle diffusion model, whereas that of Cu(II) in the absence of complexing agents such as EDTA, citric acid, and tartaric acid by the pseudo-second-order equation. Kinetic parameters of the three models and the normalized standard deviations between the measured and predicted results were also calculated and discussed. (C) 2001 Elsevier Science Ltd. All rights reserved.

Keywords: Activated Carbon, Adsorbents, Adsorption, Aqueous-Solutions, Chelating-Agents, Chitosan, Complexing Agents, Desorption, Diffusion, Equilibrium, Kinetic Modeling, Liquid-Phase Adsorption, Metal Ions, Model, Modeling, Models, Polymers, Reactive Dyes, Removal, Sorbents, Sorption

McNevin, D. and Barford, J. (2001), Inter-relationship between adsorption and pH in peat biofilters in the context of a cation-exchange mechanism. Water Research, 35 (3), 736-744.

Full Text: W\Wat Res35, 736.pdf

Abstract: A mathematical model of biofiltration McNevin and Barford (1998) has been augmented to include speciation, acid/base equilibria and pH dependence of adsorptive equilibria. It accurately predicts qualitative aspects of dynamic transients observed in an experimental perfusion column and supported a mechanism of adsorption by cation exchange with acidic functional groups on the surface of peat. It mirrored the buffering capacity of peat when solutions of high and low pH flow over the peat surface. This is a direct result of cation exchange where adsorption of cations increases with pH. This buffering capacity makes peat an attractive medium for engineered biological systems which must often operate within narrow pH bands to optimise biological activity.

Keywords: biofilter, Adsorption, Cation Exchange, pH, Mechanism, Peat

Shawwa, A.R., Smith, D.W. and Sego, D.C. (2001), Color and chlorinated organics removal from pulp mills wastewater using activated petroleum coke. Water Research,