One-step fabrication of cellulose nanofibrous membrane with anchored particulate polydopamine for multifunctional oil/water separation

Superwetting membranes with high water flux and multiple functions are desirable in industry. Herein, a one-step electrospinning strategy is proposed for constructing electrospun cellulose nanofibrous membranes containing numerous particulate polydopamine (PDA) molecules, using ethanol to delay the polymerisation rate of dopamine (DA). The effects of ethanol on the particulate PDA formation and the membrane’s pore sizes were discussed in detail. Notably, the hydrophilic particulate PDA anchored on the fibres enhanced surface roughness, thus improving the hydrophilicity of the membranes. Moreover, with an increase in the DA dosage, the pore size of the membrane decreased, while the water flux for the oil/water mixture was maintained. In addition, the as-prepared membrane could efficiently separate small-sized oil/water emulsions and particulate matter with separation efficiencies greater than 99 % because of its narrow pore size distribution and high hydrophilicity (water contact angle of ∼0°). Due to the adsorption sites on PDA, the membrane could also separate dyeing wastewater containing emulsified oils, particles, and dyes. This work offers a feasible approach to addressing the limitations of conventional electrospun polymer membranes, such as complex preparation processes, low water flux at small pore sizes, and limited ability to separate multiple types of pollutants.