Kinetic Study of Copper(II) Simultaneous Extraction/Stripping from Aqueous Solutions by Bulk Liquid Membranes Using Coupled Transport Mechanisms

Heavy metals removal/recovery from industrial wastewater has become a prime concern for both economic and environmental reasons. This paper describes a comparative kinetic study of the removal/recovery of copper(II) from aqueous solutions by bulk liquid membrane using two types of coupled facilitated transport mechanisms and three carriers of different chemical nature: benzoylacetone, 8-hydroxyquinoline, and tri-n-octylamine. The results are analyzed by means of a kinetic model involving two consecutive irreversible first-order reactions (extraction and stripping). Rate constants and efficiencies of the extraction (k1, EE) and the stripping (k2, SE) reactions, and maximum fluxes through the membrane, were determined for the three carriers to compare their efficiency in the Cu(II) removal/recovery process. Counter-facilitated transport mechanism using benzoylacetone as carrier and protons as counterions led to higher maximum flux and higher extraction and stripping efficiencies due to the higher values of both the extraction and the stripping rate constants. Acceptable linear relationships between EE and k1, and between SE and k2, were found.