Modification of polyethersulfone by grafting acrylic-acid based monomers for improved hydrophilicity and pH-responsive properties of membranes

Abstract: The quality of drinking water is continuously deteriorating due to pollutants that end up in water arising from a variety of industries. These pollutants reduce the value of water thereby posing risks to people’s health and the environment. Thus, there is a need to develop techniques that will be effective in wastewater treatment to obtain potable water. Membrane technology has increasingly become the most reliable, applicable and cost-effective technique for drinking water treatment solution. However, membrane fouling has been identified as the major obstacle to the applicability of this technique. In order to alleviate this issue, many studies have proved that improving the hydrophilicity of a membrane surface is significant. In this study, acrylic acid (AA)-based monomers (acrylic acid (AA), methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA)) were graft-polymerized onto hydrophobic polyethersulfone (PES) using benzoyl peroxide (BPO) as the chemical initiator for the development of membranes with pH-responsive and antifouling properties. The confirmation of successful grafting was done using nuclear magnetic resonance (NMR) and fourier transform infrared (FTIR) spectroscopies. Flat-sheet pristine and grafted PES membranes were prepared by phase inversion via immersion precipitation technique. The morphology of the membranes was studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Furthermore, membrane hydrophilicity and performance were investigated using contact angle measurements and dead-end filtration (pure water flux, bovine serum albumin (BSA) rejection and fouling analysis). The SEM analysis showed an increase in the pore size of the PES-g-PAA, PES-g-PMAA and PES-g-PEGDMA membranes in comparison with the pristine PES membrane. The contact angle measurements indicated significant increases in the hydrophilicities with chemical grafting of the AA-based monomers onto PES. The pH-responsive tests proved that the grafted PES membranes all...M.Sc. (Chemistry