Removal of Cadmium from Aqueous Solutions Via Emulsion Liquid Membrane Process: Batch Experimental Investigations

The objective of this study was to evaluate the efficiency of the emulsion liquid membrane (ELM) technique for cadmium removal from aqueous solutions through systematic assessment of key operating parameters. Kerosene was used as the diluent, sorbitan monooleate (Span 80) as the surfactant, Di-(2-ethylhexyl) phosphoric acid (D₂EHPA) as the carrier, and hydrochloric acid (HCl) as the stripping agent. The effects of surfactant concentration, agitation speed, internal to membrane phase ratio, emulsion to feed ratio, and HCl concentration in the internal phase were investigated. The best conditions yielded a maximum cadmium removal efficiency (η_Cd) of 97.4 % at 4 % surfactant concentration, 450 rpm agitation speed, 1 : 4 internal to membrane ratio, 1 : 3 emulsion to feed ratio, and 0.25 M HCl. The results of cadmium removal follow the second-order kinetic model. The results demonstrate that the developed ELM system is an effective and rapid method for cadmium removal, with strong potential for application in industrial wastewater treatment and heavy metal remediation.