The technical grade nonaoxyethylene oleylether carboxylic acid RO90 is investigated as surfactant for heavy metal ion removal via micellar enhanced ultrafiltration (MEUF). In contrast to sodium dodecylsulfate (SIDS), which is a standard surfactant for this purpose, RO90 has a much lower cmc (similar to 0.014 g L-1) and forms larger aggregates (similar to 8 nm). These properties render RO90 a much more efficient surfactant for MELT than SIDS. The surfactant can be filtered out very efficiently using a membrane with a MWCO <= 10 kDa and the gel layer concentration is about 170 g L-1 For a molar [RO90]/[Me2+] ratio of about 10, metal ion removal efficiency is > 95% for the investigated divalent cations Mg2+, Ni2+, Cd2+, Cu2+, Fe2+, and Zn2+. The simultaneous removal results in the following order: Fe2+ similar to Cu2+ > Cd2+ > Zn2+ > Ni2+ > Mg2+, which is a result of the different complex binding constants as shown earlier by Bunting and Thong for different alkylcarboxylates. This shows that RO90 in MEUF is a selectively binding surfactant with superior properties compared to so far employed surfactants. (C) 2015 Elsevier B.V. All rights reserved.