Anti-fouling and easy-cleaning PVDF membranes blended with hydrophilic thermo-responsive nanofibers for efficient biological wastewater treatment

Abstract

Membrane technology can minimize spread of viruses in the environment during pandemics, however, its efficiency is highly limited by biofouling. In the current study, a composite membrane composed of commercial membrane material, poly(vinylidene fluoride) (PVDF), and thermo-responsive attapulgite (t-ATP) was developed. The t-ATP was synthesized by surface modification of attapulgite (ATP) nanofiber with poly(N-isopropylacrylamide) (PNIPAM). t-ATP acted as a nucleating seed to expedite crystallization of PVDF and as a hydrophilic modifier to enhance the wetting performance of membrane. The tensile strength, elongation, and permeance of membrane increased with increase in t-ATP content without compromising pore structure. PNIPAM chains in t-ATP were swollen or shrunken with the change in temperature, thus releasing adhesion between membrane and biofoulants. The modified membrane exhibited superior biofouling resistance performance compared with the pristine PVDF membrane owing to the hydrophilic property of t-ATP and the stretchable chains on its surface. Notably, 89% of biofouling on membrane surface was easily removed through a simple temperature-change coupling ultrasonic cleaning process. High performance of the PVDF/t-ATP membrane indicates its potential application for high-efficient biological wastewater treatment.