Surface modification of alumina membranes via a sol-gel process for antifouling properties

Alumina membranes were modified using a SiO2 sol-gel process to mitigate membrane fouling. The formation of a SiO2 coating layer resulted in slightly narrowed pore sizes and reduced pure water permeability. Due to low isoelectric points, SiO2-coated membranes have a strong negative surface charge (-130 mV at pH 6.5), which results in the presence of electrostatic repulsion forces against humic acid. The membranes with higher TEOS (tetraethyl orthosilicate) concentrations exhibited higher flux levels during membrane fouling procedures, while the pristine alumina membrane displayed the lowest flux. Thus, inorganic surface modification with amorphous SiO2 clearly enhances the antifouling properties of pristine alumina membranes. (C) 2016 Elsevier B.V. All rights reserved.