Optimization of chromium extraction from aqueous solutions by emulsion liquid membrane

摘要

Taguchi method has been realized efficient for output improvement in research and development stage; so that high-quality items can be quickly produced at lower costs. Optimization of emulsion liquid membrane (ELM) for chromium extraction is achieved by Taguchi method. One of the main objectives of this work deals with the extraction of Cr(VI) using tri-octyl phosphine oxide (TOPO) as a carrier. Six parameters, namely carrier, surfactant, and internal phase concentration, feed phase pH, stirring speed and emulsion/external feed phase ratio, were chosen as the control factors while the initial concentration of chromium was chosen as the external noise factor. The results have been analyzed using analysis of variance (ANOVA) and signal-to-noise (S/N) ratio. From our results, combinations of all factors studied have a potential interaction. It can be noticed that the optimum external to emulsion ratio is the highest level. Indeed, this trend leads to treating large volumes of more dilute Cr(VI) solutions. This reflects the importance of ELM in which our system deviates from equilibrium that means a high mass transfer occurred. Maximum contribution for Cr(VI) extraction is obtained as 89.498% for TOPO concentration followed by Span 80 (4.393%), and the other parameters have a lower significance on ELM process (ranging from 1.750% to 1.299%).