<p>In this study, the Gemini micellar-enhanced ultrafiltration (GMEUF) process was employed to separate gold from a gold–palladium binary solution. The basis of the selectivity in this method is the greater interaction of one metal ion with the micelle surface and rejection by the membrane, and the higher tendency of another metal ion to form a complex with the ligand and pass through the membrane pores. The process was studied as a function of four parameters, i.e., solution pH (2–4), molar concentration ratio of the chelating agent to the metal (2.5–22.5), molar concentration ratio of the surfactant to the metal (0.5–2.5) and flow rate (70–110&#xa0;ml/min) using the response surface methodology (RSM) and central composite design (CCD). The objective of this optimization was to maximize gold rejection and minimize palladium removal simultaneously. The responses predicted by the proposed reduced quadratic model showed that using the chelating agent ethylene diamine tetra-acetic acid (EDTA) in the GMEUF process could lead to a high separation of gold (90.35%) and palladium (31.18%) ions at the optimum conditions.</p> Graphical abstract <p></p>