In the current study, the process of sunflower oil-based green emulsion liquid membrane (GELM) has been investigated for the separation of copper ions from aqueous solutions. The liquid membrane was prepared by loading with Span 80 as the surfactant, D2EHPA as the carrier, sunflower oil as the solvent and hydrochloric acid as the aqueous internal phase. The effect of the process parameters such as concentration of the surfactant, concentration of HCl, concentration of D2EHPA and the ratio of the internal phase to the organic phase in the membrane were studied using Box-Behnken design and response surface method. The results showed that more than 94% of Cu(II) ions were successfully extracted within 130 min at the optimum conditions of 104.23 mM D2EHPA, 1.44 M HCl, 3.25 wt% Span 80 and an I/O ratio of unity providing a stable emulsion. Hence, it could be concluded that sunflower oil may be considered as a high potential green diluent in water treatment and purification technology, particularly in ELM process for the removal of Cu(II) from wastewater.
