Efficient water desalination using photo-responsive ZnO polyamide thin film nanocomposite membrane

Membrane separation technology has become one ofthe most frequently used techniques to secure adequate water resources for human consumption and other domestic and industrial utilization. Thin film nanocomposite membranes are widely used in desalination, but have low photo-sensitisation efficiency because of the entrapment of nanoparticles in the polyamide layer of the membrane, which in turn reduces their exposure to ultraviolet (UV) light. To overcome this issue, we adapted polyamide thickness to be equal or less than nanoparticles size, so that the light could reach the nanoparticles. This was achieved by controlling the interfacial polymerization reaction time. ZnO nanoparticles, of 100nm, were used as a photocatalyst to enhance properties of the thin film nanocomposite membrane. Results showed that the nanoparticles were strongly linked to membrane surface and they can be easily activated by UV light. We found that short time UV irradiation of the ZnO-thin film nanocomposite membrane resulted in superior water flux, of 120Lm(-2)h(-1), and excellent fouling resistance, without jeopardizing NaCl salt rejection, at 98%. Moreover, the pre-fouled ZnO-thin film nanocomposite membrane showed excellent self-cleaning abilityafter 30s of UV treatment. Overall, this study presents an easy method to fabricate high photo-sensitisation and efficient polyamide thin film nanocomposite membrane.