Preparation and characterization of a novel polyethersulfone (PES) ultrafiltration membrane modified with a CuO/ZnO nanocomposite to improve permeability and antifouling properties

Novel polyethersulfone (PES) ultrafiltration membranes blended with different contents of the CuO/ZnO (CZN) nanocomposite were prepared by the non-solvent induced phase inversion method. High hydrophilicity of ZnO nanoparticle made it an excellent choice to be incorporated with CuO nanoparticles in order to improve the membrane properties as a nanofiller additive. Scanning electron microscopy (SEM), atomic force microscopy (AFM), mean pore size measurement, water contact angle, and energy dispersive X-ray (EDX) were used for membrane characterization. Cross-sectional SEM images showed that by the addition of the CZN up to 0.2 wt%, the morphology of the membrane had little tendency to alter from a finger-like structure to a macro-void one. However, by further increasing the CZN, the porosity was reduced. The homogenous distribution and no agglomeration of CZN, which could be seen in the surface SEM images, were the result of the proper dependency between CZN and the polymer matrix. EDX analysis presented the homogenous dispersion of the nanoparticles in the PES matrix. AFM images also showed that the surface roughness was not changed significantly by the CZN concentration. However, the calculated roughness parameters showed that CZN addition up to the optimum value (0.2 wt%) could be effective in decreasing the roughness of the membrane surface. The mixed matrix membrane up to the optimum value of CZN (0.2 wt%) presented the improved properties in water permeability and fouling resistance. When the content of CZN was 0.2 wt%, the pure water flux growth of the blended membrane was about 32%. In addition, the cited blended membrane displayed a higher flux recovery ratio (FRR (%)) in the bovine serum albumin (BSA) fouling agent. BSA rejection was above 95% for all of the nanocomposite membranes.