Phosphonium Modified Nanocellulose Membranes with High Permeate Flux and Antibacterial Property for Oily Wastewater Separation

Abstract Nanocellulose membranes could efficiently separate oily wastewater because of their superhydrophilic and underwater superoleophobic property and nanoporous structure. However, the practical application and storage of nanocellulose membranes were limited by their low water permeation flux and easy corrosion by bacteria, respectively. Herein, nanocellulose membranes with high permeate flux and antibacterial property were fabricated by grafting tetrakis(hydroxymethyl) phosphonium chloride (THPC) onto the surface of tunicate cellulose nanofibers (TCNFs) via esterification reaction. The introduction of THPC groups with tetrahedral structure on the surface of TCNFs significantly improved the pore size and interlayer space of nanocellulose membranes, resulting in the increasing of water permeation flux. These THPC@TCNF membranes were superhydrophilic and underwater superoleophobic, which could effectively separate various oil/water nanoemulsion. Moreover, THPC@TCNF membranes possessed excellent durability, mechanical stability, and cycling performance. Due to the presence of positively charged phosphonium groups, THPC@TCNF membranes exhibited excellent antibacterial property against B. subtilis that is a typical Gram-positive bacterium presenting in oily wastewater. This works provided a facile method to endow nanocellulose membrane with high permeate flux and antibacterial property.