Oxidant-Induced High-Efficient Mussel-Inspired Modification on PVDF Membrane with Superhydrophilicity and Underwater Superoleophobicity Characteristics for Oil/Water Separation

In this work, a facile one-step approach was developed to modify hydrophobic polyvinylidene fluoride (PVDF) microfiltration membrane with superhydrophilicity and underwater superoleophobicity properties via a high-efficient deposition of polydopamine (PDA) coating oxidized by sodium periodate in a slightly acidic environment (pH = 5.0). In contrast to the traditional PDA coating on hydrophobic membranes autoxidized by O₂ in a weak basic buffer solution, the superhydrophilicity and ultrahigh pure water permeability (about 11 934 L m^-2 h^-1 under 0.038 MPa) of the PDA-decorated PVDF membrane are derived from optimized chemical oxidation without postmodifications or additional reactants. The as-prepared membrane exhibits excellent oil/water separation ability evaluated by water fluxes and oil rejection ratios of various oil/water mixtures and oil-in-water emulsions. Moreover, the outstanding antifouling performance and reusability of the PDA-modified PVDF membrane provide a long-term durability for many potential applications. The modified membrane also exhibits excellent chemical stability in harsh pH environments and mechanical stability for practical applications.