Sunflower oil was employed instead of common n-alkanes as the organic phase in preparing a green emulsion liquid membrane (GELM) for water decolorization. Methyl violet 2B dye was selected as contaminant. The proposed GELM included Span 80 as surfactant, hydrochloric acid as the internal phase, and edible sunflower oil as the diluent. Firstly, the effect of influencing parameters on the decolorization capability of GELM was investigated by Plackett–Burman screening design. Afterward, in order to achieve optimal conditions, the most important parameters were investigated by the Box–Behnken design. The optimal experimental conditions resulted in more than 97% dye separation.
