Atomic layer deposition of TiO2 on porous polysulfone hollow fibers membranes for water treatment

Abstract

Numerous membranes devoted to water treatment are made of Polysulfone (PSF) and can suffer from performance deterioration because of the intrinsic hydrophobicity of this material. Modifying membrane surface allows the engineering of its physicochemical properties and can achieve improved permeability and anti-fouling efficiency by tuning the membrane hydrophilicity or porosity. Atomic layer deposition (ALD) is a unique technology that provides highly conformal and uniform coatings layers such as oxides over surfaces of three-dimensional (3D) parts, porous materials and particles. In this work, titanium dioxide (TiO2) was deposited on polysulfone hollow fibers (HF) membranes via ALD using TiCl4 and H2O as precursors. Membranes obtained with increasing number of deposition ALD cycles were tested until the pores were totally blocked. The morphology, structure and mechanical properties of membranes were not altered. The deposition was confirmed by scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX) and X-ray Photoelectron Spectroscopy (XPS) analyses. The deposition of TiO2 enhanced by 50% the water permeability and by 20% the fouling resistance of the PSF HF membranes until only 20 ALD cycles. This is accompanied by an increase of hydrophilicity and a pores size reduction.