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.
Textile industry effluent contains a high amount of toxic colorants. These dyes are carcinogenic and threats to the environment and living beings. In this study, poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) was used as the based polymer for PIMs with bis-(2-ethylhexyl) phosphate (B2EHP) and dioctyl phthalate (DOP) as the carrier and plasticizer. The fabricated PIMs were employed to extract the cation dye (Malachite Green; MG) from the feeding phase. PIMs were also characterized by scanning electron microscopy (SEM), atomic force microscope (AFM), contact angle, water uptake, Fourier-transform infrared spectroscopy (FTIR) and ions exchange capacity. The performance of the PIMs was investigated under various conditions such as percentage of carrier and initial dye concentration. With permeability and flux values of 0.1188 cm/min and 1.1913 mg cm/min, PIM produced with 18% w/w PVDF-co-HFP, 21% w/w B2EHP, 1% w/w DOP and 40% w/w THF and was able to achieve more than 97% of MG extraction. The experimental data were then fitted with a pseudo-second-order (PSO) model, and the calculated R2 value was ~0.99. This shows that the data has a good fit with the PSO model. PIM is a potential alternative technology in textile industry effluent treatment; however, the right formulation is crucial for developing a highly efficient membrane.
In the present work, a highly efficient mixed matrix membrane (MMM) for humic acid (HA) removal was developed. Multiwalled carbon nanotubes (MWCNTs) were functionalized in the presence of 3-methacryloxypropyl trimethoxysilane using the co-condensation method and were subsequently loaded with TiO2 (prepared via the sol-gel route). The as-prepared material was then incorporated into a PES polymer solution to prepare a fMWCNT-TiO2/PES hybrid membrane via non-solvent induced phase inversion. The microstructure of the membrane was characterized using Fourier transform infrared spectroscopy, atomic force microscopy, scanning electron microscopy, water contact angle, thickness, porosity, and pore size. The fMWCNT-TiO2/PES hybrid membrane was tested for the removal of HA and antifouling performance. The results show that the surface hydrophilicity of the membranes was greatly improved upon the addition of the fMWCNT-TiO2 particles. The results show that 92% of HA was effectively removed after 1 h of filtration. In comparison with pristine membrane, the incorporation of fMWCNT-TiO2 nanoparticles led to enhanced pure water flux (99.05 L/m2 h), permeate flux (62.01 L/m2 h), higher HA rejection (92%), and antifouling improvement (RFR: 37.40%, FRR: 86.02%). Thus, the fMWCNT-TiO2/PES hybrid membrane is considered to be a great potential membrane for the improvement of ultrafiltration membranes.