Enhanced hydrophilicity and controlled pore size distribution of polyvinylidene fluoride membranes through segregation and grafting for protein anti-fouling

Abstract

Membrane technology is essential in water treatment due to its efficiency and scalability. Polyvinylidene fluoride (PVDF)-based membranes face significant fouling issues and modification difficulty due to low surface energy and high hydrophobicity. This study introduces an innovative and facile approach combining segregation and grafting techniques to address these challenges. The environmentally friendly material cellulose acetate was incorporated into the PVDF matrix, where it segregated onto the membrane surface during the formation process. Following this, hydrolysis introduced hydroxyl groups, and the membrane was further functionalized by grafting oxidized carboxymethyl cellulose, a cost-effective and biodegradable polymer, onto its surface. This dual-step modification significantly enhances hydrophilicity and surface negative charge density, while also playing a crucial role in modulating pore size and distribution. The modified A-H-SSM-20 membrane exhibits dynamic water contact angle of 0° within 40 s and zeta potential of −75.2 mV at pH 7.0. Additionally, mean pore size decreased from 33.7 to 23.9 nm, while static bovine serum albumin adsorption dropped from 83.8 to 11.6 μg·cm⁻². The irreversible fouling ratio decreased significantly from 33.0 % to 0.5 %, demonstrating marked improvement in anti-fouling performance. This approach provides promising solution for enhancing fouling resistance in PVDF membranes, facilitating potential for applications in water treatment.