Haiqing Lin1

1, SUNY Buffalo, Buffalo, New York, United States

Stimuli-response membranes have been widely explored to mitigate fouling on the membrane surface to achieve long-term performance of water purification. Herein, we demonstrate a facile, one-step coating of photo-mobile materials on membrane surface to impart self-cleaning property upon exposure to ultraviolet (UV) light. Specifically, we successfully deposited 4,4’-azodianiline (AZO) on the surface of ultrafiltration (UF) membranes by co-depositing with a bio-glue of polydopamine (PDA). In the presence of UV light, the AZO undergoes photoisomerization from trans-AZO to cis-AZO while increasing surface hydrophilicity and shrinking the volume. When the UV light is switched off, the cis-AZO transits reversibly to the trans configuration. The photo-mobile behavior and the resulting volume reversible change contributes to the self-cleaning properties. The effect of the coating layer on the surface hydrophilicity and pure water permeance is systematically evaluated. The photoresponsive properties of AZO in DMF solutions and thin films with PDA is characterized using UV-Vis absorption spectroscopy. The self-cleaning behavior of the modified membranes is demonstrated in treating water containing bovine serum albumin (BSA) as a model foulant. For example, the self-cleaning of polysulfone UF membranes increases water flux by 200% when treating 1 g/L BSA aqueous solution.