A separation-adsorption coupled composite membrane with oxygen plasma-etched ZIF-8-derived carbon for complex oil-water emulsion separation

Membrane separation technology encounters significant challenges in achieving simultaneous separation and purification of oily wastewater contaminated with heavy metal ions. Herein, ZIF-8 derived mesoporous carbon etched by oxygen plasma (DMC-OP X ) was used as a functional component for adsorbing heavy metal ions and blended with hydrophilic copolymers PVDF- g -PHEMA into the PVDF casting solution, enabled the fabrication of an advanced nanocomposite membrane (M-H-DMC-OP X ) with separation-adsorption functionality through NIPS method. The characterization results indicate that oxygen plasma etching significantly increases the oxygen-containing groups on DMC-OP X surfaces enhancing hydrophilicity, heavy metal adsorption capacity, and mitigating flux reduction caused by unmodified DMC incorporation. Calculation analyses demonstrate that the oxygen-containing groups on DMC-OP X surface can form hydrogen bonding networks with PVDF- g -PHEMA chains, thereby improving the tensile strength of M-H-DMC-OP X membrane. The one-step separation experiments on oil-water emulsions containing Cu 2 + , Pb 2+ , Cr 3+ , Fe 3+ , and Co 2+ demonstrate that the M-H-DMC-OP 6 membrane exhibits outstanding oil-water separation efficiency and heavy metal removal efficiency, reaching over 99.2 % and 82.4 %, respectively. This work developed a multifunctional separation membrane for complex oily wastewater and established a feasible strategy for improving the water flux of nanocomposite membranes.