Simultaneous removal of nickel and zinc from aqueous solution by micellar-enhanced ultrafiltration and activated carbon fiber hybrid process

Simultaneous removal of nickel and zinc from aqueous solution by the micellar-enhanced ultrafiltration and activated carbon fiber (MEUF-ACF) hybrid process was performed at a constant permeate flow rate (40 mL/min) and operating retentate pressure (1 bar). The anionic surfactant, sodium dodecyl sulfate (SDS), was applied to enhance the removal efficiency of the ultrafiltration at molar ratios, SDS:Ni(II):Zn(II), ranging from 8.5:1:1 to 59.5:1:1. It was found that at the membrane molecular weight cut-off (MWCO) of 100 kDa and at the molar ratio of 25.5:1:1, the removal efficiencies of Ni(II), Zn(II) and SDS by MEUF alone were 96.3%, 96.7% and 61.0%, respectively. However, the MEUF-ACF hybrid process with the 100 kDa MWCO membrane and at the same molar ratio removed Ni(II), Zn(II) and SDS by 99.3%, 99.9% and 78.8%, respectively. It seemed that an SDS concentration higher than its critical micelle concentration (CMC) was a suitable dose for the MEUF system. It was clearly observed from the results that concentration polarization of micelles played a major role in removal of Ni(II), Zn(II), and SDS. In addition, under the constant permeate flow rate, the ACF component of the hybrid process was able to act as a good quality control unit for metal removal.