The blending of additives in the polyethersulfone (PES) matrix is an important approach in the membrane industry to reduce membrane hydrophobicity and improve the performance (flux, solute rejection, and reduction of fouling). Several (hydrophilic) modifications of the PES membrane have been developed.Given the importance of the hydrophilic modification methods for PES membranes and their applications, we decided to dedicate this review solely to this topic. The types of additives embedded into the PES matrix can be divided into two main categories: (i) polymers and (ii) inorganic nanoparticles (NPs). The introduced polymers include polyvinylpyrrolidone, chitosan, polyamide, polyethylene oxide, and polyethylene glycol. The introduced nanoparticles discussed include titanium, iron, aluminum, silver, zirconium, silica, magnesium based NPs, carbon, and halloysite nanotubes. In addition, the applications of hydrophilic PES membranes are also reviewed. Reviewing the research progress in the hydrophilic modification of PES membranes is necessary and imperative to provide more insights for their future development and perhaps to open the door to extend their applications to other more challenging areas.
IntroductionPolyethersulfone (PES) is a recognized polymeric material, which is widely employed in the fabrication of membranes for various applications. Due to its high glass transition temperature (225 C), and amorphous and transparent properties, PES possesses a high mechanical and hydrolytic stability, thermal and chemical resistance, and outstanding oxidative characteristics, 1 making it ideal for the preparation of asymmetric membranes with different surfaces and pore sizes.
1-3Asymmetric PES membranes are generally prepared via a phaseseparation method. The nal membrane properties and performance are inuenced by the composition (additives,
View Article OnlineView Journal | View Issue concentration, and solvent), temperature of the doping solution, the non-solvent or the mixture of non-solvents, and the coagulation bath or the environment. 4 The risk of the fouling effect due to the high hydrophobicity of PES, especially in protein-contacting applications and aqueous ltrations, limits their wide applications.2,3 Numerous research studies have reported efforts to enhance the hydrophilicity of the PES membrane surface.
1,5Basically, the water contact angle (WCA) formed between the membrane-liquid boundary and liquid-gas tangent is generally employed to evaluate the hydrophilic properties of the membrane.6 Commercial PES membranes are hydrophobic in nature with high mechanical, chemical, and thermal stability.
7Usually, these membranes possesses high WCA values and are prone to solute adsorption from various feed streams. It has been well documented that membranes with hydrophilic surfaces are less prone to the fouling effect with microorganisms and organic substances due to: (i) a decreased interaction between the membrane surface and foulant, and (ii) no interaction of hydrogen bonds in the boundary layer betw...
