Electrospun Polyurethane Nanofiber Membranes for Microplastic and Nanoplastic Separation

Multifunctional materials for industrial wastewater treatment are in high demand due to the contamination of micro- and nanoplastics (MNPs) and dyes. Herein, we demonstrate a polyurethane-based (PU) electrospun composite membrane for MNP separation and selective methylene blue (MB) adsorption. The optimized 20 wt % graphene oxide-montmorillonite (GO-Mt)-loaded nanofibrous composite membrane (20-PGT) exhibited its superhydrophilicity with a water contact angle of 0° and high water flux. It displayed a maximum pressure-driven water flow of 8163 L m–2 h–1 and a gravity-driven water flux of 793 L m–2 h–1. Three model MNPs, such as acrylonitrile butadiene styrene (ABS), polystyrene (PS), and poly(methyl methacrylate) (PMMA) with various sizes, have been demonstrated. The adsorptive separation and size-exclusive interception mechanisms were observed for nanoplastics (NPs) and microplastics (MPs), respectively. Cake formation, intermediate blocking, and standard blocking mechanisms were followed during the filtration of ABS MPs, PMMA NPs, and PS NPs, respectively. Additionally, the composite membrane exhibited selective MB adsorption from the mixture of dyes, with a maximum adsorption capacity of 417 mg g–1. Langmuir adsorption isotherm and pseudo-second-order kinetics define the adsorption isotherm and adsorption kinetics, respectively. The fabricated, robust fibrous composite membrane opens a wider door for the removal of MNPs and MB from contaminated water.