An integrated strategy for achieving oil-in-water separation, removal, and anti-oil/dye/bacteria-fouling

Abstract Numerous strategies on the application of superwettable membranes for oil/water (O/W) separation have been proposed; however, few works on one-step separation strategies and the separation mechanism of complex O/W effluents containing organic dye and bacteria have been reported. Here, an integrated strategy for O/W separation, removal, and anti-oil/bacteria/dye-fouling is firstly proposed. A hydrogel fabricated PVDF@ZnO/Ag (H-PVDF@ZnO/Ag) membrane is designed with a superhydrophilic/underwater superoleophobic surface and hierarchical membrane channels, which exhibits superior separation efficiency (99.4%) and flux (1700 L m−2 h−1 bar−1). Considering the wettability, the interface intrusion pressure influences the O/W separation. Also considering the energy and molecular kinetics, the differences in the interaction energy and mean square displacement (MSD) of the water and oil molecules with the membrane obtained by molecular dynamics (MD) simulations are the internal factors influencing the O/W separation. The experimental and MD simulation results demonstrate that the high organic dye removal efficiency (>99%) is attributed to the synergistic effect between the hydrogel electrostatic adsorption and the ZnO/Ag photodegradation. The excellent anti-oil/dye/bacteria-fouling is due to the low oil adhesion, hydration layer, photodegradation, and antibacterial activity. Introducing an amino resin to the membrane increases the membrane’s tolerance and resistance to mechanical damage and chemical attack due to the intertwined cross-linking network and hydrogen bonds. The membrane also exhibits effective separation of real wastewater from jeans factory. This strategy may inspire further research on the treatment of complex O/W effluents.