Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6970450 | Journal of Hazardous Materials | 2016 | 7 Pages |
Abstract
Solid/liquid extraction of Cr(VI) was accomplished using trioctylphosphine oxide impregnated polypropylene hollow fiber membranes. Extraction of 100-500Â mg/L Cr(VI) by the extractant impregnated membranes (EIM) was characterized by high uptake rate and capacity, and equilibrium was attained within 45Â min of contact. Extraction equilibrium was pH-dependent (at an optimal pH 2), whereas stripping using 0.2Â M sodium hydroxide yielded the highest recovery of 98% within 60Â min. The distribution coefficient was independent of initial Cr(VI) concentration, and the linear distribution equilibrium isotherm could be modeled using Freundlich isotherm. The mass transfer kinetics of Cr(VI) was examined using pseudo-second-order and intraparticle diffusion models and a mass transfer mechanism was deduced. The distribution coefficient increased with temperature, which indicated endothermic nature of the reaction. Enthalpy and entropy change during Cr(VI) extraction were positive and varied in the range of 37-49Â kJ/mol and 114-155Â J/mol, respectively. The free energy change was negative, confirming the feasibility and spontaneity of the mass transfer process. Results obtained suggest that EIMs are efficient and sustainable for extraction of Cr(VI) from wastewater.
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Authors
Prashant Praveen, Kai-Chee Loh,