A novel approach for oil/water separation: Integrating nano-ZnO with graphene oxide membranes via dopamine and KH550

Graphene oxide-based membranes, known for unique permeability and selectivity in oil/water separation, face limitations due to low flux and weak anti-fouling performance. To overcome these challenges, a series of GO@ZnO membranes were synthesized in a one-pot process, doping different amounts of nano-ZnO into GO with the aid of polydopamine (PDA) and 3-triethoxysilylpropylamine (KH550). This study found that evenly distributed nano-ZnO within the GO layers acted as hydrophilic intercalators, creating continuous rough nanochannels and increased interlayer spacing for effective water transport. The membrane M-5 demonstrated a significant increase in water permeability, reaching 5718 ± 151 L m−2 h−1 bar−1, nearly 20 times higher than the control group (M-0) without ZnO doping. Anti-fouling tests, using four different oil/water emulsions, showed that M-5 consistently achieved oil rejection rates above 99.7%. Furthermore, M-5 exhibited a flux recovery rate (FRR) of 95.5%, surpassing M-0 by 34.6%. Regeneration experiments confirmed that M-5 maintained an impressive oil rejection rate of 99.2% after 30 recycling cycles. These results indicate that nano-ZnO enhances surface roughness and hydration layers, significantly improving water permeability without compromising rejection rate and anti-fouling performance. The study presents a straightforward approach to creating continuous nanochannels and hydrophilic layers in two-dimensional laminar GO membranes, highlighting the potential of GO@ZnO membranes in oil-water treatment applications.