Evaluation of the emulsion liquid membrane performance on the removal of gadolinium from acidic solutions

This work evaluates the performance of emulsion liquid membrane (ELM) for the extraction of gadolinium(III) from acidic solution. The ELM was made up of di-(2-ethylhexyl) phosphoric acid (D2EHPA) as carrier, Span 80 (sorbitol monooleate) as emulsifying agent, commercial kerosene as organic diluent and Nitric acid as stripping phase. Important physical and chemical variables affecting the ELM performance for the extraction of gadolinium (III) such as carrier concentration, mixing time, surfactant concentration, agitation speed, initial pH of the feed phase, internal phase concentration, treatment ratio, and feed phase concentration were systematically investigated. Results indicated that the highest gadolinium(III) extraction can be attained after 10 min of mixing by using 0.05 M D2EHPA, 1.5% (v/v) Span 80, 1.0 M nitric acid as stripping phase at feed phase pH of 2, agitation speed of 180 rpm, and treatment ratio of 1:10. At the optimum condition, simultaneous quantitative extraction (>99%) and stripping (>79%) of gadolinium were achieved. Furthermore, the overall mass transfer coefficient was calculated and the results revealed that the extraction was interfacially controlled. (C) 2018 Elsevier B.V. All rights reserved.