Micellar enhanced ultrafiltration (MEUF): activated carbon fiber (ACF) hybrid process using low surfactant concentration for zinc(II) removal from synthetic wastewater

Zinc(II) removal from synthetic wastewater by micellar enhanced ultrafiltration (MEUF) using low sodium dodecyl sulfate (SDS) concentration and 300 kDa molecular weight cut-off (MWCO) membrane was studied. Effects of various parameters like initial permeate flux, retentate pressure, molar ratio of zinc(II) to SDS, initial zinc(II) concentration, MWCO, and solution pH were analyzed. Considering zinc(II) removal rate and permeate flux, initial permeate flux of 43.64 L/mh, retentate pressure of 0.20 MPa, molar ratio of zinc(II) to SDS of 1:2, and neutral pH condition were found to be optimum operating parameters. Although initial SDS concentrations were far below critical micelle concentration, average zinc(II) removal rate was 77.29 and 75.93% whereas, absolute permeate flux was 39.64 and 10.45 L/mh at molar ratios of zinc(II) to SDS of 1:8 and 1:2, respectively. It was observed that concentration polarization played a crucial role in zinc(II) removal. In MEUF-ACF hybrid process at constant initial zinc(II) concentration (0.42 mM) and initial SDS concentration (0.21 mM), average zinc(II) removal rate was 8.65, 12.70, 10.84%, while SDS removal rate was 10.5, 12.6, 11.52% higher than MEUF alone in 30, 100, 300 kDa membranes, respectively