Surface modified bacterial biosorbent with poly(allylamine hydrochloride): Development using response surface methodology and use for recovery of hexachloroplatinate(IV) from aqueous solution
Department of New Paradigm for BIN Fusion Technology, WCU Project, Chonbuk National University, Jeonbuk 561-756, Republic of Korea. Water Research
(Impact Factor: 5.53).
12/2010; 44(20):5919-28. DOI: 10.1016/j.watres.2010.07.034
In this study, poly(allylamine hydrochloride) (PAA/HCl) was cross-linked with fermentation bacterial waste (Escherichia coli) in order to introduce a large amount of amine groups as binding sites for potassium hexachloroplatinate(IV), as a model anionic pollutant. The sorption performance of PAA/HCl-modified E. coli was greatly affected by the dosages of PAA/HCl and crosslinker (epichlorohydrin, ECH), and by the pH of the modification reaction medium. These factors were optimized through the response surface methodology (RSM). A three-level factorial Box-Behnken design was performed, and a second-order polynomial model was successfully used to describe the effects of PAA/HCl, ECH and the pH on the Pt(IV) uptake (R(2) = 0.988). The optimal conditions that were obtained from the RSM were 0.49 g of PAA/HCl, 0.05 mL of ECH and pH 10.02, with 1.0 g of dried E. coli biomass. The biosorption isotherm and kinetics studies were carried out in order to evaluate the sorption potential of the PAA/HCl-modified E. coli that was prepared under the optimized conditions. The sorption performance of the developed bacterial biosorbent was 4.36 times greater than that of the raw E. coli. Desorption was carried out using 0.05 M acidified thiourea and the biosorbent was successfully regenerated and reused up to four cycles. Therefore, this simple and cost-effective method suggested here is a useful modification tool for the development of high performance biosorbents for the recovery of anionic precious metals.
Available from: Sok Kim
- "The poly(allylamine hydrochloride)-modified biosorbent was prepared following previously reported method . Briefly, 10 g of dried E. coli biomass was mixed with 100 mL PAA/HCl solution (6%, w/v), then incubated for 2 h at 25 ± 2 °C, while the pH was controlled to be at 10. Next, 0.5 mL ECH (99%) was dropped into the suspension of PAA/HCl and E. coli for crosslinking for 2 h. "
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ABSTRACT: In this study, the cationic bacterial biosorbent, poly(allylamine hydrochloride) (PAA/HCl)-modified Escherichia coli, was successfully immobilized as a chitosan fiber, which was proved to be a sustainable biosorbent for platinum removal and recovery from aqueous solutions in batch and column systems. Compared to the commercial ion exchange resins, PAA/HCl-modified E. coli chitosan fiber showed a quite good performance for Pt(IV) removal. Two-parameter (Langmuir and Freundlich) and three-parameter (Sips and Redlich–Peterson) models were employed to describe the batch isotherm experimental data. Among these four models, the Redlich–Peterson model fit best, with higher coefficient of determination, chi-square and average percentage error values. Thermodynamic parameters (ΔG0 < 0 and ΔH0 > 0) showed the spontaneity and endothermic nature of biosorption process. The kinetics of Pt(IV) biosorption with different initial concentrations were better fit by the pseudo-second-order model, with higher coefficient of determinations and more closely predicted qe values. An acidified 0.005 M thiourea was used to regenerate platinum from exhausted biosorbent maintaining desorption efficiencies over 90.2% until five cycles. In the column studies, the breakthrough curve showed a typical S-shaped curve, with breakthrough and exhaustion times appearing at 36.0 h and 52.5 h, respectively, which was opened up a possibility of column regeneration.
Available from: Peter Matúš
- "Platinum is generally unreactive and dissolves in aqua regia to give soluble hexachloroplatinic acid. This compound has various applications in photography, zinc etchings , indelible ink, plating, mirrors, porcelain coloring, and as catalysts for various chemical reactions   . The increasing demand for platinum, combined with the limited resources available, has led to increasing interest in the recovery of this strategic element . "
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ABSTRACT: In this work, removal of Pt(IV) from aqueous solutions was investigated. Batch adsorption experiments using nanometer-sized titanium dioxide (nano-TiO2) as a sorbent were performed for this purpose. The optimal pH for the maximal adsorption of Pt(IV) was found to be pH 4.0. The kinetic data were analyzed on the basis of pseudo-firstorder and pseudo-second-order kinetic models. The correlation results suggested that the adsorption process followed pseudo-second-order kinetic model. The results obtained from equilibrium adsorption studies were fitted to Langmuir and Freundlich adsorption isotherm models. The adsorption isotherm was better fitted by the Langmuir isotherm equation, and the maximal adsorption capacity of the sorbent was 8.75 mg/g according to this isotherm. Besides, desorption of Pt(IV) from nano-TiO2 was studied using various eluents. Sufficiently efficient desorption (around 86%) was achieved by using 2% thiourea in 2M HCl. Finally, nanoTiO2 was used for separation/ preconcentration and determination of trace platinum in synthetic fresh waters.
Available from: Sibel Tunali Akar
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ABSTRACT: The biosorption properties of APDC modified S. albus were tested in batch and column conditions. Effective experimental parameters such as pH, biosorbent dosage, contact time, temperature, initial lead(II) ion concentration, flow rate and bed height were investigated. The biosorption capacity of modified biosorbent was at maximum when lead(II) solution pH and biosorbent dosage were 5.5 and 2.0 g L(-1), respectively. The biosorption equilibrium was established in 20 min. Langmuir isotherm fitted well to the equilibrium data and kinetics is found to fit pseudo-second-order model. Increase in ionic strength of lead(II) solutions caused a slight decrease in the biosorption yield of APDC-modified biosorbent. Co-ions affected the biosorption performance of modified biomass up to maximum 20.81% reduction. Column biosorption of lead(II) showed higher biosorption yields at lower flow rates. Required time of breakthrough point was found to be 200 min. The recommended mechanism was found to depend mainly on electrostatic interaction, ion-exchange and complex formation. The ion-exchange mechanism for lead(II) biosorption onto the modified biosorbent is verified from the ionic strength effect and EDX analysis. Carbonyl, phosphate and CN groups on the modified surface of S. albus were found to responsible for complexation with lead(II).
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