Biodegradable CA-based nanofiber membranes with ZnO/SnO2 heterojunctions for efficient emulsion separation and photocatalytic self-cleaning

A CA-based nanofiber membrane with ZnO/SnO2 heterojunctions (d-CA@ZnO/SnO2) was fabricated by electrospinning and deacetylation process. • Efficient O/W emulsion separation performance was guaranteed due to the boosted hydrophilicity, and underwater oleophobicity. • ZnO/SnO 2 heterostructures allowed the membrane to achieve an exceptional photocatalytic self-cleaning efficiency. • Discarded membranes were able to biodegrade naturally, providing an eco-friendly wastewater treatment solution. Organic pollutant-induced membrane failure and microplastic accumulation derived from discarded spent membranes pose severe obstacles to the sustainable development of oil/water (O/W) separation membrane technology. In this study, a self-cleaning and biodegradable deacetylated cellulose acetate nanofiber membrane modified with ZnO/SnO 2 heterojunctions (d-CA@ZnO/SnO 2 ) was fabricated by electrospinning and deacetylation process. Simultaneous stripping removal of acetyl groups and polyvinylpyrrolidone fillers effectively enhanced the surface roughness of the membrane, which greatly improved its hydrophilicity and underwater oleophobicity. Benefiting from such favorable surface properties, the d-CA@ZnO/SnO 2 membrane exhibited outstanding separation performance for various O/W emulsions, resulting in the higher permeation flux (∼ 972.25 L·m −2 ·h −1 ) and separation efficiency (∼ 98.2%). Due to the staggered band alignment of ZnO/SnO 2 heterostructures, the charge carrier recombination was prominently suppressed, which allowed the membrane to achieve an exceptional photocatalytic self-cleaning efficiency with a flux recovery rate exceeding 95% via ultraviolet-driven active photodegradation of organic foulants. Meanwhile, enzymatic degradation tests confirmed that the discarded membrane could be disintegrated into fine fragments within cellulase solutions, which presented a practical and eco-friendly approach for oily wastewater purification without causing secondary microplastic pollution. Download: Download high-res image (152KB) Download: Download full-size image