A paraffin-wax-infused porous membrane with thermo-responsive properties for fouling-release microfiltration

Abstract

Membrane fouling is one of the major problems in microfiltration processes. Slippery liquid infused surface with outstanding antifouling property provides a new strategy to solve membrane fouling, however, the loss of the lubricant hinders its long-term application underwater. Here we demonstrate a thermo-responsive paraffin-wax-infused membrane, which accommodates both stability and slippery feature of lubricant by adjusting the temperature. The membrane is prepared by filling melted paraffin wax in the rough structures of the silica coatings on the polyethersulfone (PES) membrane surface through suction filtration. The paraffin layer can cover the whole membrane surface, including the micropore wall. The paraffin wax of solid phase leads to a hydrophobic surface, and shows highly stability on the membrane, which can withstand shear from spinning, flowing water or filtration. When paraffin wax turns to liquid phase at temperatures above its melting point, the membrane surface transforms to slippery state that can resist bovine serum albumin (BSA) and bacterial adhesion. In the cross-flow microfiltration, excellent fouling-release performance and durability are achieved by the temperature responsive switching between the hydrophobic and slippery state; after three cycles of fouling by BSA and cleaning with water of 60 °C, the membrane with optimum amount of paraffin wax shows much higher flux and flux recovery (>90%) compared to the control membrane without paraffin wax.