Development of superhydrophobic PVA/CNC nanofibrous membranes for enhanced oil-water separation

Abstract

Effective oil–water separation is crucial for environmental purification and the remediation of oil pollution, yet current methods face limitations in efficiency, durability, and environmental impact. In this study, we aimed a green nanofibrous membrane with excellent oil–water separation efficiency, addressing the significant environmental challenge of separating oil from water in various states. For this purpose, polyvinyl alcohol (PVA)-based nanofibers were prepared by aqueous electrospinning. The mechanical strength of the nanofibers was reinforced by adding cellulose nanocrystals (CNCs). The surface of the nanofibers was modified with hexadecyltrimethoxysilane (HDTMS) to induce hydrophobicity, evidenced by the increase in contact angle from 44.41° to 133.19°, facilitating effective oil separation from various states, including dispersed, suspended, and emulsified states. The prepared PVA/CNC-HDTMS nanofiber showed 194 %, 539 %, and 407 % higher tensile strength, yield strength, and Young’s modulus than PVA nanofibers, respectively. The oil sorption capacity of the nanofibers varied widely from 17.01-113.76 g/g, which is strongly influenced by the viscosity and volatility of the oil species. The durability and reusability of the nanofibers were well maintained, even after being reused more than 10 times without morphological deterioration. In separating oil–water mixtures, the nanofibers maintained a high flux of 40,039 L/m2h and a separation efficiency of 99.2 % under pressurized conditions. Additionally, the nanofibers achieved a separation efficiency of 98.5 % in oil–water emulsion states.