Screening of parameters and optimization of nickel extraction by green emulsion liquid membrane using statistical experimental design

Abstract

This study focuses on the extraction of nickel ions from an aqueous solution using a green emulsion liquid membrane (GELM). Its primary objective is to choose between corn oil and sunflower oil as a solvent in GELM and compare their performance with a kerosene-based emulsion liquid membrane (ELM). The membrane phase was made by dissolving the carrier (D2EHPA) and the surfactant (tween 80), in the solvents. Subsequently, the membrane was emulsified with the stripping agent (sulphuric acid) to produce the GELM. A Plackett–Burman design was employed to determine the key parameters influencing nickel extraction. Among the considered parameters, treatment ratio, surfactant concentration, carrier concentration, and stripping agent concentrations were identified as the significant factors affecting nickel extraction. Parameters such as stirring speed and time, external phase pH, and phase ratio were found to be non-significant and were kept constant. The central composite design method was employed to determine the optimum value of the key parameters. Under the optimal conditions, 98.1% of the nickel ions were successfully extracted. The feasibility of recycling the membrane phase was examined, and the performance of GELMs prepared using both fresh and recovered membrane phases was analyzed. The experimental results showed that the extraction efficiency decreased by 1.02% and 7.99% after two membrane recycling cycles, which was still within the acceptable range.