Personal Research Database

Full Text: W\Wat Res37, 4770.pdf

Abstract: To increase the uptake capacity of mercury ions, several chemical modifications of chitosan beads which are cross-linked with glutaraldehyde were performed. Among them, aminated chitosan bead prepared through chemical reaction with ethylenediamine had a high uptake capacity of about 2.3 mmol g^-1 dry mass at pH 7. The increased number of amine groups was confirmed by IR analysis and measuring the saturation capacities for adsorption of HCl. The surface condition and existence of mercury ions on the beads was confirmed by the environmental scanning electron microscope and energy dispersive X-ray spectroscopy instrumental analyses. The beads showed the characteristic of competitive sorption between mercury and hydrogen ions and it was successfully modelled by an equilibrium model.

Keywords: Chitosan, Heavy Metals, Metal Removal, Adsorption, Modification, Polysaccharides

Rivas, F.J., Beltrán, F., Gimeno, O., Acedo, B. and Carvalho, F. (2003), Stabilized leachates: Ozone-activated carbon treatment and kinetics. Water Research, 37 (20), 4823-4834.

Full Text: W\Wat Res37, 4823.pdf

Abstract: Ozone has been used as a pre-oxidation step for the treatment of stabilized leachates. Given the refractory nature of this type of effluents, the conversion of some wastewater quality parameters has been moderate after 1 h of ozonation (i.e. 30% chemical oxygen demand (COD) depletion). Ozone uptake was calculated in the interval 1.3–1.5 g of ozone per gram of COD degraded. An optimum dose of ozone has been experienced in terms of biodegradability of the processed effluent (60 min of treatment, 1×10^-3 molL^-1 ozone inlet feeding concentration and 50 Lh^-1 gas flow-rate). pH and other typical hydroxyl radical generator systems exerted no influence on the efficiency of the process, suggesting the negligible role played by the indirect route of oxidation (generation of hydroxyl radicals). The ozonated effluent was thereafter treated in a second adsorption stage by using a commercial activated carbon. Removal levels up to 90% of COD in approximately 120 h were experienced for adsorbent dosages of 30 gL^-1. Both steps, the single ozonation and the adsorption stage have been modelled by using different pseudoempirical models.

Keywords: Leachate, Landfill, Ozone, Activated Carbon, Wastewater

Álvarez-Ayuso, E., García-Sánchez, A. and Querol, X. (2003), Purification of metal electroplating waste waters using zeolites. Water Research, 37 (20), 4855-4862.

Full Text: W\Wat Res37, 4855.pdf

Abstract: The sorption behaviour of natural (clinoptilolite) and synthetic (NaP1) zeolites has been studied with respect to Cr(Ill), Ni(II), Zn(II), Cu(II) and Cd(II) in order to consider its application to purify metal finishing waste waters. The batch method has been employed using metal concentrations in solution ranged from 10 to 200 mg/l and solid/liquid ratios ranged from 2.5 to 10 g/1. The Langmuir model was found to describe well all sorption processes, allowing to establish metal sorption sequences from which the main retention mechanism involved for each metal has been inferred. Synthetic zeolite exhibited about 10 times greater sorption capacities (b(Cr) = 0.838 mmol/g, b(Ni) = 0.342 mmol/g, b(Zn) = 0.499 mmol/g, b(Cu) = 0.795 mmol/g, b(Cd) = 0.452 mmol/g) than natural zeolite (b(Cr) = 0.079 mmol/g, b(Ni) = 0.034 mmol/g, b(Zn) = 0.053 mmol/g, b(Cu) = 0.093 mmol/g, b(Cd) = 0.041 mmol/g), appearing, therefore, as most suitable to perform metal waste water purification processes. This mineral showed the same high sorption capacity values when used in the purification of metal electroplating waste waters. (C) 2003 Elsevier Ltd. All rights reserved.

Keywords: Waste Waters, Purification, Zeolites, Heavy Metals, Sorption, Ion-Exchange, Fly-Ash, Natural Clinoptilolite, Cadmium, Adsorption, Solvation, Binary, Cu²⁺, Fe³⁺, Pb²⁺

Vegliò, F., Beolchini, F. and Prisciandaro, M. (2003), Sorption of copper by olive mill residues. Water Research, 37 (20), 4895-4903.

Full Text: W\Wat Res37, 4895.pdf

Abstract: A study on olive mill residues (OMR) as copper adsorbing material is reported in this work. A rough characterization of this waste material has been performed, by microanalysis and SEM pictures. Sorption tests with suspended OMR evidenced copper removal from solution, of about 60% in the investigated experimental conditions. The COD release in solution was also monitored during biosorption. Considering that it was significant, OMR washings with water were performed before biosorption. In this case the COD release in solution was reduced to less than 600 mg/L after two washings, while the OMR metal sorption properties did not change. Regenerated residues by acid solutions gave a copper removal of about 40%, in the same experimental conditions of the first adsorption test: regeneration with EDTA at different concentrations suggested that it presents a damage of adsorption active sites. On the other hand, the use of HCl and CaCl₂ led to completely regenerate the biosorbent material. Tests were also performed with a column filled with 80 g of OMR and the breakpoint was demonstrated to take place after that about 1 L solution was treated in the investigated experimental conditions. Regeneration tests permitted to demonstrate that a concentration factor of about 2 can be obtained in no-optimized conditions, highlighting the possibility of using OMR for the treatment of metal bearing effluents. The main advantage of the process would be the ‘low cost’ biosorbing material, considering that it represents a waste in the olive oil production.

Keywords: Olive Mill Residues, Adsorption, Copper, Kinetic, Equilibrium, Regeneration

Sublet, R., Simonnot, M.O., Boireau, A. and Sardin, M. (2003), Selection of an adsorbent for lead removal from drinking water by a point-of-use treatment device. Water Research, 37 (20), 4904-4912.

Full Text: W\Wat Res37, 4904.pdf

Abstract: The removal of lead from drinking water was investigated to develop a point-of-use water filter that could meet the regulation imposed by the new European Directive 98-83 lowering lead concentration in drinking water below 10 g L^-1. The objective of this research was to assess the potential of different adsorbents (zeolites, resins, activated carbon, manganese oxides, cellulose powder) to remove lead from tap water with a very short contact time. To begin, the repartition of the lead species in a tap water and a mineral water was computed with the computer model CHESS. It showed that in bicarbonated waters lead is mainly under lead carbonate form, either in the aqueous or in the mineral phase. Batch experiments were then conducted to measure the equilibrium adsorption isotherms of the adsorbents. Then, for five of them, dynamic experiments in micro-columns were carried out to assess the outlet lead concentration level. Three adsorbents gave rise to a leakage concentration lower than 10 g L^-1 and were then selected for prototypes experiments: chabasite, an activated carbon coated with a synthetic zeolite and a natural manganese oxide. The proposed method clearly showed that the measurement of equilibrium isotherms is not sufficient to predict the effectiveness of an adsorbent, and must be coupled with dynamic experiments. (C) 2003 Elsevier Ltd. All rights reserved.

Keywords: Lead Removal, Drinking Water, Adsorption Isotherm, Adsorption Kinetics, Column Experiments, Point-of-Use Filter, Aqueous-Solution, Ion-Exchange, Cadmium, Metals

Horsfall, Jr., M. and Abia, A.A. (2003), Sorption of cadmium(II) and zinc(II) ions from aqueous solutions by cassava waste biomass (Manihot sculenta Cranz). Water Research, 37 (20), 4913-4923.

Full Text: W\Wat Res37, 4913.pdf

Abstract: The sorption of two divalent metal ions, Cd(II) and Zn(II), onto untreated and differentially acid-treated cassava waste biomass over a wide range of reaction conditions was studied at 30°C. The metal ion removal from the spent biomass was also measured. The batch experiments show that pH 4.5–5.5 was the best range for the sorption of the metal ions for untreated and acid-treated biomass. Time-dependent experiments for the metal ions showed that for the two metals examined, binding to the cassava waste biomass was rapid and occurred within 30 min and completed within 1 h. High sorption capacities were observed for the two metals. The binding capacity experiments revealed the following amounts of metal ions bound per gram of biomass: 86.68 mg/g Cd, 55.82 mg/g Zn and 647.48 mg/g Cd, 559.74 mg/g Zn for untreated and acid-treated biomass, respectively. It was further found that the rate of sorption was particle-diffusion controlled, and the sorption rate coefficients were determined to be 2.30×10^-1 min^-1 (Cd²⁺), 4.0×10^-3 min^-1 (Zn²⁺) and 1.09×10^-1 min^-1 (Cd²⁺), 3.67×10^-2 min^-1 (Zn²⁺) for 0.5 and 1.00 M differential acid treatment, respectively. Desorption studies showed that acid treatment inhibited effective recovery of metal ions already bound to the biomass as a result of stronger sulfhydryl-metal bonds formed. Less than 25% of both metals were desorbed as concentration of acid treating reagent increases. However, over 60% Cd and 40% Zn were recovered from untreated biomass during the desorption study. The results from these studies indicated that both untreated and acid-treated cassava waste biomass could be employed in the removal of toxic and valuable metals from industrial effluents.

Keywords: Heavy Metal Binding, Cassava Waste, Wastewater Treatment, Thiolation, Manihot Sculenta Cranz

Fan, X., Parker, D.J. and Smith, M.D. (2003), Adsorption kinetics of fluoride on low cost materials. Water Research, 37 (20), 4929-4937.

Full Text: W\Wat Res37, 4929.pdf

Abstract: Adsorption is one important technique in fluoride removal from aqueous solutions. The viability of adsorption techniques is greatly dependent on the development of adsorptive materials. A large number of materials have been tested at a fluoride concentration greater than 2 mg/l, and the lowest limit for fluoride reduction by them is about 2 mg/l. Decreasing the fluoride concentration to less than 2 mg/l, most of the tested materials displayed a very low capacity of fluoride removal.

This paper has concentrated on investigating the adsorption kinetics and adsorption capacity of low cost materials at a low initial fluoride concentration. The experiments were carried out at a natural pH, and radioisotope ¹⁸F rather than ¹⁹F was used since ¹⁸F can be rapidly measured by measuring the radioactivity with a resolution of 1×10^-13 mg or 0.01 Ci. The tested materials are hydroxyapatite, fluorspar, calcite, quartz and quartz activated by ferric ions. Their adsorption capacities follow the order:

Hydroxyapatite>Fluorspar>Quartz activated using ferric ions>Calcite>Quartz

The uptake of fluoride on hydroxyapatite is an ion-exchange procedure and follows the pseudo-first- and second-order equations, while the uptake of fluoride on the others is a surface adsorption and follows the pseudo-second-order equation. Calcite has been seen as a good adsorbent in fluoride removal and has been patented. However, our data suggested that its adsorption capacity is only better than quartz.

The external mass transfer is a very slow and rate-determining step during fluoride removal from the aqueous solution. Under static conditions, there was no relative movement between adsorbents and solutions, the fluoride uptake was at a very slow rate and the adsorbent properties did not significantly affect the fluoride uptake. Under shaken conditions, the adsorption of fluoride was controlled by the adsorbent structure and chemical properties.

Keywords: Fluoride, Adsorption Kinetics, Hydroxyapatite, Fluorspar, Calcite, Quartz

Notes: highly cited

Janoš, P., Buchtová, H. and Rýznarová, M. (2003), Sorption of dyes from aqueous solutions onto fly ash. Water Research, 37 (20), 4938-4944.

Full Text: W\Wat Res37, 4938.pdf

Abstract: Brown coal fly ashes were tested as potentially low-cost sorbents for the removal of synthetic dyes from waters. It was shown that both basic (cationic) as well as acid (anionic) dyes can be sorbed onto the fly ash. The adsorption can be described by the multi-site Langmuir isotherm. The sorption capacities were in the range of 10^-1–10^-3 mmol/g and did not differ significantly for basic and acid dyes. The dye sorption decreased in the presence of organic solvents (methanol, acetone). The presence of oppositely charged surfactants exhibited a pronounced effect on the dye sorption––low concentrations of the surfactant enhanced sorption, whereas high concentrations solubilized the dyes and kept them in solution. Inorganic salts exhibited only a minor effect on the dye sorption. The sorption of basic dyes increased at high pH values, whereas the opposite was true for acid dyes.

Keywords: Acid Dyes, Basic Dyes, Sorption, Fly Ash, Wastewater Treatment

Ghimire, K.N., Inoue, K., Yamaguchi, H., Makino, K. and Miyajima, T. (2003), Adsorptive separation of arsenate and arsenite anions from aqueous medium by using orange waste. Water Research, 37 (20), 4945-4953.

Full Text: W\Wat Res37, 4945.pdf

Abstract: Cellulose and orange waste were chemically modified by means of phosphorylation. The chemically modified gels were further loaded with iron(III) in order to create a suitable chelating environment for arsenate and arsenite removal. The loading capacity for iron(III) on the gel prepared from orange waste (POW) was 1.21 mmol g^-1 compared with 0.96 mmol g^-1 for the gel prepared from cellulose (PC). Removal tests of arsenic with the iron(III)-loaded gel were carried out batchwise and by using a column. Arsenite removal was favored under alkaline condition for both PC and POW gels, however, the POW gel showed some removal capability even at neutral pH. On contrary, arsenate removal took place under acidic conditions at pH=2–3 and 2–6 for the PC and POW gels, respectively. Since iron(III) loading is higher on the POW gel than on the PC gel greater arsenic removal has been achieved by the POW gel compared with the PC gel. It can be concluded that the POW gel can be used for the removal and recovery of both arsenite and arsenate from arsenic contaminated wastewater.

Keywords: Adsorption, Arsenite, Arsenate, Phosphorylated Cellulose, Phosphorylated Orange Waste, Ion Exchange

Palma, G., Freer, J. and Baeza, J. (2003), Removal of metal ions by modified Pinus radiata bark and tannins from water solutions. Water Research, 37 (20), 4974-4980.

Full Text: W\Wat Res37, 4974.pdf

Abstract: Pinus radiata bark and tannins, chemically modified with an acidified formaldehyde solution were used for removing metal ions from aqueous solutions and copper mine acidic residual waters. The adsorption ability to different metal ions [V(V), Re(VII), Mo(VI), Ge(IV), As(V), Cd(II), Hg(II), Al(III), Pb(II), Fe(II), Fe(III), Cu(II)] and the factors affecting their removal from solutions were investigated. Effect of pH on the adsorption, desorption, maximum adsorption capacity of the adsorbents, and selectivity experiments with metal ion solutions and waste waters from copper mine were carried out. The adsorbents considerably varied in the adsorption ability to each metal ion. The adsorption depends largely upon the pH of the solution. Modified tannins showed lower adsorption values than the modified bark. For the same adsorbent, the maximum capacity at pH 3 for the different ions were very different, ranging for modified bark from 6.8 meqg^-1 for V to 0.93 meqg^-1 for Hg. Waste waters were extracted with modified bark as adsorbent and at pH 2. The ions Cu(II) (35.2 mgL^-1), Fe(III) (198 mgL^-1), Al(III) (83.5 mgL^-1) and Cd(II) (0.15 mgL^-1) were removed in 15.6%, 46.9%, 83.7% and 3.3%, respectively, by using 1 g of adsorbent/10 mL of waste water. In general, a continuous adsorption on a packed column gave higher adsorbed values than those observed in the batchwise experiment.

Keywords: Adsorbents, Adsorption, Bark, Binding, Cellulosic Materials, Coniferous Wood Bark, Copper, Copper Ions, Effluents, Heavy-Metals, Metal Ions, Peanut Shells, Recovery, Scavengers, Tannins, Uranium Uptake, Waste, Waste Water, Wastewaters

Min, B., Evans, P.J., Chu, A.K. and Logan, B.E. (2004), Perchlorate removal in sand and plastic media bioreactors. Water Research, 38 (1), 47-60.

Full Text: W\Wat Res38, 47.pdf

Abstract: The treatment of perchlorate-contaminated groundwater was examined using two side-by-side pilot-scale fixed-bed bioreactors packed with sand or plastic media, and bioaugmented with the perchlorate-degrading bacterium Dechlorosoma sp. KJ. Groundwater containing perchlorate (77 g/L), nitrate (4 mg-NO₃/L), and dissolved oxygen (7.5 mg/L) was amended with a carbon source (acetic acid) and nutrients (ammonium phosphate). Perchlorate was completely removed (<4 g/L) in the sand medium bioreactor at flow rates of 0.063–0.126 L/s (1–2 gpm or hydraulic loading rate of 0.34–0.68 L/m² s) and in the plastic medium reactor at flow rates of <0.063 L/s. Acetate in the sand reactor was removed from 43±8 to 13±8 mg/L (after day 100), and nitrate was completely removed in the reactor (except day 159). A regular (weekly) backwashing cycle was necessary to achieve consistent reactor performance and avoid short-circuiting in the reactors. For example, the sand reactor detention time was 18 min (hydraulic loading rate of 0.68 L/m² s) immediately after backwashing, but it decreased to only 10 min 1 week later. In the plastic medium bioreactor, the relative changes in detention time due to backwashing were smaller, typically changing from 60 min before backwashing to 70 min after backwashing. We found that detention times necessary for complete perchlorate removal were more typical of those expected for mixed cultures (10–18 min) than those for the pure culture (<1 min) reported in our previous laboratory studies. Analysis of intra-column perchlorate profiles revealed that there was simultaneous removal of dissolved oxygen, nitrate, and perchlorate, and that oxygen and nitrate removal was always complete prior to complete perchlorate removal. This study demonstrated for the first time in a pilot-scale system, that with regular backwashing cycles, fixed-bed bioreactors could be used to remove perchlorate in groundwater to a suitable level for drinking water.

Keywords: Backwashing, Bioaugmentation, Bioreactor, Chlorate, Drinking Water, Fixed-Bed Reactor, Groundwater, Perchlorate, Sand

Netpradit, S., Thiravetyan, P. and Towprayoon, S. (2004), Evaluation of metal hydroxide sludge for reactive dye adsorption in a fixed-bed column system. Water Research, 38 (1), 71-78.

Full Text: W\Wat Res38, 71.pdf

Abstract: The capacity and performance of small-scale column, containing coarse particles of metal hydroxide sludge, were evaluated using 30 mg l⁻¹ dye solutions of C.I. Reactive Red 141. The studied bed depths were 2.5–20 cm and the studied flow rates were 1.1, 2.2 and 3.3 ml min⁻¹ cm⁻². At the breakthrough point of 0.1 C_t/C₀, the breakthrough volume was increased with increasing bed depth or decreasing flow rate, due to an increase in empty bed contact time (EBCT). The data followed the bed depth service time model, and the adsorption capacity was 24–26 mg cm⁻³ or 27–29 mg dyes g⁻¹ adsorbent. The minimum bed depths should be higher 1.02, 2.04 and 2.59 cm with flow rates of 1.1, 2.2 and 3.3 ml min⁻¹ cm⁻², respectively, while the ratio of bed depth to diameter should not be higher than 6. With EBCT above 5 min, the usage rate of metal hydroxide sludge was 1.3 g l⁻¹. Using the bed depth of 5 cm and the flow rate of 0.55 ml min⁻¹ cm⁻², 87% of dominant colour, 78% of COD, and 99% of SS could be removed from the textile wastewater, and the leachate of toxic heavy metals was under the standard limitations.

Keywords: Adsorbent, Adsorption, Breakthrough, Color Removal, Dye, Dye Adsorption, Dyes, Fixed Bed, Fixed-Bed Column, Flow Rate, Heavy Metals, Metal Hydroxide, Particles, Reactive Dye, Reactive Dyes, Waste-Water, Wastewater

Antizar-Ladislao, B. and Galil, N.I. (2004), Biosorption of phenol and chlorophenols by acclimated residential biomass under bioremediation conditions in a sandy aquifer. Water Research, 38 (2), 267-276.

Full Text: W\Wat Res38, 267.pdf

Abstract: Phenol and chlorophenols are common environmental contaminants. The fate and transport of these chemicals must be sufficiently understood to predict detrimental environmental impacts and to develop technically and economically appropriate remedial action to minimise environmental degradation. in order to gain a better understanding of the many mechanisms influencing the fate of phenol and chlorophenols in a sandy aquifer, we conducted biosorption experiments with biomass collected from a simulated aquifer polluted by consecutive accidental spills of phenol, 2-monochlorophenol, 2,4,6-trichlorophenol and pentachlorophenol under continuous bioremediation conditions following a closed-loop configuration during 180 days. A comparative study of the biosorption capacity of phenol and chlorophenols characterised by different physicochemical properties, at different pHs in the range of 6.00.1 to 9.00.1 showed the following: (i) the biosorption of phenol and chlorophenols on resident biomass was rapid (equilibrium reached in less than 2 h); (ii) the experimental data followed the Freundlich isotherm; (iii) changes in pH from 6.00.1 to 9.00.1 resulted in a decrease in the equilibrium biosorption capacity (q(eq)); (iv) both Freundlich parameters (K-F, n) should be used together as predictive parameters in mathematical models to simulate the fate of phenol and chlorophenols in the aquifer; (v) q(eq) of phenol and chlorophenols investigated in this study were satisfactorily correlated to their hydrophobicity (K-ow) with a correlation factor 0.98. In addition, available data from other reported studies fell in the same correlation curve. The results of the present study should be introduced in mathematical models developed to predict the effect of biomass fate and transport of contaminants in aquifers during bioremediation conditions. (C) 2003 Elsevier Ltd. All rights reserved.

Keywords: Bioremediation, Biosorption, Fate of Chlorophenols, Freundlich Isotherm, Hydrophobicity, Activated-Sludge, Chlorinated Phenols, Organic Pollutants, Sorption, Soil, Pentachlorophenol, Biodegradation, Desorption, Adsorption, Transport

Kim, E., Benedetti, M.F. and Boulègue, J. (2004), Removal of dissolved rhenium by sorption onto organic polymers: Study of rhenium as an analogue of radioactive technetium. Water Research, 38 (2), 448-454.

Full Text: W\Wat Res38, 448.pdf

Abstract: Technetium (Tc-99) is one of the main components of nuclear wastes. Tc characteristics can be predicted by studying rhenium. (Re-75), one of its chemical analogue, thus avoiding the use of a radioactive element at high concentrations. The objectives of this experimental study was to understand the sorption behavior of Re with natural organic materials in order to define the possible condition of Tc uptake in case where Tc may be transferred into surface or ground waters. As the well-defined organic sorbents we chose chitosan which contains amine -NH₂ groups; poly-galacturonic acid (PGA) and poly-styrene sulfonates (PSS) which contain respectively carboxyl -COOH and sulfonate -SO₃H groups. Concerning the reaction of Re with PGA or with PSS, no interaction between Re and carboxyl or sulfonate groups was found within the detection limit of this study. Re sorption on chitosan was found to be dependent on ionic strength and pH. We propose that non-specific sorption of perrhenate ion ReO₄^- via electrostatic interaction takes place at the protonated amine groups NH₃⁺. The polymer-solution interface can be described by the electric diffuse double layer model combined with the Langmuir-Freundlich model. The calculation is in good agreement with our experimental results. (C) 2003 Elsevier Ltd. All rights reserved.

Keywords: Rhenium, Technetium, Sorption, Organic Polymers, Chitosan, Nuclear Wastes, Metal-Ions, Chitosan, Adsorption, Pertechnetate, Binding

Martins, R.J.E., Pardo, R. and Boaventura, R.A.R. (2004), Cadmium(II) and zinc(II) adsorption by the aquatic moss Fontinalis antipyretica: Effect of temperature, pH and water hardness. Water Research,