Liquid surfactant membrane for lead separation from aqueous solution: Studies on emulsion stability and extraction efficiency

Abstract

As an alternative extraction technique, Liquid Surfactant Membrane (LSM) reveals several benefits in terms of efficiency, cost effectiveness and easy demulsification post extraction, without altering the chemistry of the oil phase. In this study, the extraction and re-extraction of lead (Pb) from aqueous solution via the liquid surfactant membrane (LSM) technique are investigated. LSM contains Bis-2-ethylhexyl phosphoric acid (D2EHPA) as a carrier, H2SO4 as the internal phase, kerosene as the diluent stabilized by the surfactant (Span 80), all of which have been used to investigate its ability to extract the Pb from aqueous solutions. The effect of the Span 80 concentration, homogenizer speed, extractant concentration, the volume ratio of an organic to an internal phase (O/I), stripping phase (H2SO4) concentration and the emulsified time on the LSM stability and its extraction efficiency were studied. The reused oil phase showed an extraction percentage which was as high as the original oil phase. Besides, from the results it was clear that the removal of more than 98% of the Pb from feed solutions was possible, with the emulsion breakage below 2.8% after 10 min of contact time under the best-operating conditions for the original and reused emulsions.