Excessive use of surfactants in metal waste treatment by the MEUF process resulted a secondary pollution. To overcome the problem, the combination of the acidification method followed by ultrafiltration is an efficient and simple surfactant recovery method. This research studied the effect of pH value on surfactant recovery, metal ion rejection and surfactant micelle formation at low surfactant concentrations. The retentate solution that will be recovered is obtained through the initial MEUF process using Sodium Dodecyl Sulphate (SDS) with an initial concentration of 7 mM less than the Critical Micelle Concentration (CMC), Cu2+ metal ion solution used as the pollutant feed. The recovery process carried out at various pH, namely 3; 2; 1 and 0,5. The separation between metal ions and surfactants increased as the pH value decreased. Optimal surfactant recovery at pH 0,5 with a value of recovery surfactant of 61% and metal ion rejection of 72%. The formation of micelle affects the recovery process by ultrafiltration membranes. At pH 0,5 the surfactant CMC value can decrease up to 69% compared with the pure SDS surfactants CMC value (8,16 mM). The research shows that surfactant micelles formed even under CMC value of pure surfactant by the addition of acid.

Keywords : MEUF; Acidification; Recovery; Surfactant.