by an electrolytic process from synthetic solution prepared to simulate a concentrate waste stream of a micellar-enhanced ultrafiltration process

Electroplating method was employed to recover copper and surfactant simultaneously from synthetic solutions prepared to simulate concentrated waste stream generated from micellar-enhanced ultrafiltration. Effects of surfactant and copper (II) concentrations, surfactant to copper (II) molar ratio (S/M), electroplating voltage and time, solution pH, and ionic strength on metal recovery and electrical current efficiency were investigated. Results show that at a fixed S/M ratio of 5, the first-order kinetic constant for Cu (II) removal by electroplating increases with decreasing SDS concentration. At fixed SDS concentration of 8.5 mM, increasing initial Cu (II) concentration increases both Cu (II) recovery and current efficiency. Electrolyte pH has profound effects on the metal recovery and current efficiency due to the difference in solution conductivity after pH adjustment and the extent of Cu (II) adsorption onto SDS at different pHs.

In this paper, we have investigated electroplating methods for simultaneous recovery of copper and SDS surfactant from MEUF waste stream. The results of this study can be summarized as follows: (1) Optimum condition for copper, SDS recovery efficiencies and electrical current efficiency is at cell voltages of –0.5V vs. Ag/AgCl. (2) At fixed S/M ratio of 5, the surfactant concentration as high as 17 mM has negligible effects on metal recovery and current efficiency. (3) When SDS concentration was maintained constant (8.5 mM), increasing Cu (II) concentration increased both Cu (II) recovery and current efficiency. (4) Both dissociation of SDS at pH higher than its pKa and conductivity can explain the pH effect on Cu (II) recovery and electrical current efficiency at different pHs.