A new outlook on membrane enhancement with nanoparticles: The alternative of ZnO

Although several studies explored the use of nanoparticles as additives in membrane structures, mixed matrix membranes still suffer from difficulties in synthesis and applications. In this paper, a new outlook on enhancement of membranes with nanoparticles is proposed by using ZnO as an alternative to TiO2. Although ZnO has attractive features that potentially could fill the objectives of mixed matrix membranes with lower cost and better performance, challenges in development remain. This paper investigates the synthesis of ZnO enhanced membranes and evaluates the performance of mixed matrix membranes with ZnO nanoparticles. Polyethersulfone (PES) membranes manufactured by diffusion induced phase inversion in N-methyl-pyrrolidone (NMP) using a range of procedures were blended with ZnO nanoparticles in a wide range of concentrations from ultralow to high (0.035–4 wt%). It was shown that the new membrane materials embedded with ZnO nanoparticles have significantly improved membrane features. The influence of the ZnO nanoparticles on the characteristics of PES/ZnO membranes was investigated with microscopic observations, contact angle measurement, filtration experiments, fouling resistance determination and observation of the rejection of selected dyes. The results showed an overall improvement compared to the neat membranes in terms of permeability as well as dye rejection and fouling resistance by adding ZnO nanoparticles even in small and ultralow concentrations.

► ZnO nanoparticles are an excellent competitor to TiO2 as anti-fouling material.
► Zn blended PES membrane has higher permeability than neat membrane.
► Rejection of dye solution can be improved remarkably with Zn blended PES membrane.
► Membrane performance is enhanced at unusually low concentration of ZnO particles.