Extraction and permeation studies of Cd(II) in acidic and neutral chloride media using Cyanex 923 on supported liquid membrane

A process to remove and recover cadmium from wastewater has been developed which includes solvent extraction and supported liquid membrane transport for Cd(II) using Cyanex 923 as an extractant/carrier. The influence of acid and chloride ion concentration on the extraction of Cd(II) was studied. In acidic medium, the appearance of a third phase was observed and the limiting organic concentration for Cd(II) in 5 and 10% Cyanex 923/Exxsol D100 at different concentrations of H+ ions were determined. The effect of aliphatic and aromatic diluents on the extraction and permeation of Cd(II) in neutral and acidic medium was studied and permeation coefficients were evaluated, together with the influence of third phase and pore size on transport of Cd(II) through microporous membrane. It was found that the appearance of a third phase in acidic medium could be avoided by using an aromatic diluent. In order to improve the stability of supported liquid membrane and to scale up for continuous operation, the performance of hollow fiber strip dispersion (HFSD) technique for the extraction/recovery of Cd(II) from acidic as well as neutral chloride media was examined. This study emphasizes the potential of a HFSD system to be a part of sustainable wastewater treatment technologies, enabling the separation/recovery of cadmium.