Some Aspects of the Synthesis, Characterization and Modification of Poly(ether)sulfone Polymeric Membrane for Removal of Persistent Organic Pollutants in Wastewater Samples

Abstract

The disposal of persistent organic pollutants (POPs) in water streams continues to be a challenge, where textile and pharmaceutical industries are major contributors to this global challenge. This review paper focuses on chemical and physical modification processes in place to successfully increase the performance of poly(ether)sulfone polymeric membranes with a much more improved hydrophilicity for the removal of POPs. This work is carried out for the effective and efficient removal of persistent organic pollutants in wastewater treatment plants. Poly(ether)sulfone remains the most preferred polymer in the synthesis and application of nano-filtration (NF) and ultra-filtration (UF) membranes. Using specific composition values, the phase inversion process is used for the distribution of additives or particles unto the membrane scaffold in order to fabricate the PES polymer. This tends to influence the polymer’s ideal chemical, mechanical and thermal stability. However, an observed high hydrophobicity is its main shortcoming, which frequently leads to the increased membrane fouling and flux. The performance of PES can however be improved by fabrication with suitable additives, and this automatically increases the hydrophilicity of the synthesized membrane. An approach in the PES modification differs in processes, (1) graft polymerization, where nano and micro particles are chemically imparted on the membrane scaffold; (2) plasma treatment, which uses chemical radicals and electronically excited particles, or gas under atmospheric pressure; and (3) physical pre-adsorption of hydrophilic components onto the membrane scaffold. Also, the bulk modification process was discussed further in this work as it seeks to bring a new approach in the modification process of PES membrane. This applies modification of the membrane materials before membrane synthesis by incorporating hydrophilic additives in the membrane matrix solution during the synthesis. Sulfonation and carboxylation techniques are discussed at the core of their mechanisms. In conclusion, polymer blending results in separation efficiencies being increased significantly and also resulting in improved surface characteristics.