Removal of zinc by emulsion liquid membrane using lecithin as biosurfactant

Abstract

The present investigation deals with zinc extraction using emulsion liquid membrane (ELM) method with the help of lecithin as biosurfactant. The emulsion liquid membrane system consists of paraffin as organic phase, lecithin as biosurfactant, Di-(2-ethylhexyl) phosphoric acid (D2EHPA) as extractant, and sulfuric acid as stripping agent. In this study, five parameters affecting the extraction performance, i.e., lecithin concentration, pH of feed solution, treatment ratio, internal phase to organic phase volume ratio, and D2EHPA concentration were investigated. The stability of emulsion was determined by specifying breakage and swelling of the emulsion. The experiments were performed under ambient conditions to extract zinc with the initial concentration of 250 mg/L. The extraction step was completed after 10 minutes by stirring at 500 rpm. Optimal conditions were obtained at the biosurfactant concentration of 3% (v/v), pH 3, treatment ratio 0.3, internal phase to organic phase volume ratio 0.1, and D2EHPA concentration 6% (v/v). Under optimal conditions, zinc extraction was 98.38%. In these conditions, the breakage and swelling of the emulsion were 6.29% and 8.56%, respectively.