Sustainable and antibacterial sandwich-like Ag-Pulp/CNF composite paper for oil/water separation

Bio-based membranes for emulsion separation are sustainable, low-cost, renewable, biodegradable, and nontoxic. Herein, an antibacterial sandwich-like composite paper was fabricated by a facile process using Ag nanoparticles (Ag NPs)-coated pulp fibers and cellulose nanofibrils (CNFs). The obtained Ag-Pulp/CNF composite paper was superhydrophilic, allowing a 96 % separation efficiency for various oil-in-water emulsions. This outstanding separation efficiency was maintained over 20 separation cycles. The composite paper also showed satisfactory separation performance for water-in-oil emulsions after modification to render the surface hydrophobic. The CNFs provided the composite a nanoscale pore, which rejected nearly 100 % of bacteria when used to filter bacteria-contaminated emulsions due to a physical barrier effect. Attributed to the intrinsic antibacterial capability of Ag NPs, the composite paper exhibited strong antibacterial performance against Escherichia coli . Thus, the composite paper that was mainly derived from sustainable pulp fibers exhibited potential performance for oil/water separation and water purification.