Development of All-Cellulose Ultrafiltration Membranes for High-performance Wastewater Treatment

All-cellulose membranes, developed entirely from natural biomass resources, have untapped potentials for a wide range of water purification applications, including wastewater treatment. In this study, we prepared water-resistant but super hydrophilic all-cellulose membranes with high porosity (~80%). The demonstrated membrane system consists of a Lyocell microfiber scaffold infused with cellulose nanofibers (CNF) crosslinked by polyamideamine-epichlorohydrin (PAE); where the system showed good mechanical strength (wet stress: 3.5 - 8.0 MPa), pH resistance, and stability in hot water. The optimized all-cellulose membrane exhibited high permeation flux (8.8 ± 1.5 L/m²×h×psi), excellent separation efficiency (> 99.9%), good flux recovery ratio (> 95%), and self-healing property for wastewater filtration, compared with the commercial polymeric membranes such as polyvinylidene difluoride (PVDF) and polyether sulfone (PES) membranes. Moreover, the fouling mechanism was investigated by the resistance-in-series and three combined cake-filtration models. This study illustrated the promising potential of using all-cellulose membranes for high-efficient wastewater treatment and its superior antifouling performance compared to existing commercial ultrafiltration membranes.