Oleylethoxycarboxylate - An efficient surfactant for copper extraction and surfactant recycling via micellar enhanced ultrafiltration

The nonaoxyethylene oleylether carboxylic acid Akypo R090 VG, a surfactant with ionic character at high pH and non-ionic character at low pH, has been investigated with respect to copper removal from aqueous streams via micellar enhanced ultrafiltration (MEUF) with subsequent copper and R090 separation using the method of cloud point extraction (CPE). Almost quantitative Cu2+ removal is obtained in MEUF and more than 90% Cu2+ is separated from R090 in CPE. The investigation of Cu2+/R090 complexes with small-angle neutron scattering (SANS) shows almost no structural change of R090 micelles in the presence of Cu2+. These results show the importance of the surfactant head group for optimizing the specific interaction with the ion to be extracted. This optimization and the ability to recycle the surfactant by a temperature variation and using the cloud point phenomenon is an elegant approach to achieve efficient metal ion extraction. (c) 2014 Elsevier Inc. All rights reserved.