Micellar-enhanced ultrafiltration of methylene blue from dye wastewater via a polysulfone hollow fiber membrane

Micellar-enhanced ultrafiltration (MEUF) of methylene blue (MB) from dye wastewater was explored for obtaining colorless water, using a 10-kDa molecular weight cut-off (MWCO) polysulfone hollow fiber membrane and sodium dodecylsulfate (SDS) as an anionic surfactant. The effects of factors, such as operating pressure, feed SDS, MB and sodium chloride (NaCl) concentrations, on the permeate flux (J) and additional resistance (Rf) as well as the observed MB and SDS rejection were investigated. Moreover, the zeta potential of SDS micelle with feed SDS, MB and NaCl concentrations in the solution was also quantified. The rejection of MB and SDS decreased slightly with operating pressure increasing. It was observed that the permeate flux decreased while the additional resistance increased with increased SDS and MB concentrations in the feed. The addition of NaCl significantly increased surfactant retention and reduced the back contamination. The rejection of MB and SDS were 99.3 and 96.0%, respectively, with MB (6 mg/L), SDS (8 mM) and NaCl (200 or 300 mM) in the solution.