Layer by layer (LBL) processes have been widely used for various membrane applications, including surface modification of microfiltration (MF), ultrafiltration (UF) and supported graphene oxide (GO) membranes. Here we report a modified LBL approach using ultrasonic spray, with a case study of depositing polydopamine (PDA) and anatase TiO2 nanoparticles onto UF polyvinylidene fluoride (PVDF). We hypothesize that molecular level control of the deposition process increases photocatalytic activity of crystalline and anatase TiO2 nanoparticles. However, improved surface property control and industrial scalability are needed to drive this technology forward. In this study, surface properties of commercial polyvinylidene fluoride (PVDF) ultrafiltration membranes were modified using dopamine self-polymerization followed by ultrasonic spray deposition of anatase TiO2 nanoparticles. Modified membranes were characterized using scanning electron microscopy and water contact angle. To test our hypothesis, PDA and anatase TiO2 nanoparticles were sprayed onto PVDF via a LBL approach by systematically varying spraying parameters, including the hot plate temperature and the number of spray cycles. Additionally, ultraviolet illumination was exploited to activate photocatalytic properties of anatase TiO2. The effect of UV intensity on water flux and antifouling properties was carefully evaluated for all the TiO2 modified membranes samples. To summarize, the reported ultrasonic spray technique provides an easy route to modify membrane surfaces in high-volume manufacturing environments with molecular control over nanoparticle adhesion and distribution.

Optimizing layer by layer approach via ultrasonic spray technique: A case study of depositing anatase titanium dioxide and polydopamine to reduce fouling while enhancing water flux

255th National Meeting (2018)

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