Degradation of Pollutants in Solid and Gas States Using Waterborne Acrylic Nanocomposite Paints

Abstract

In this study, TiO₂/SiO₂ nanocomposite were synthesized using titanium tetraisopropoxide (TTIP) and tetraethoxysilane (TEOS) in a two-step sol-gel route. FTIR, XRD, UV-Vis, and XPS techniques were used to characterize the synthesized nanoparticles. Field Emission Scanning Electron Microscopy was utilized to evaluate the particle size of the synthesized nanoparticles (30.35±4.52 nm). Photo-degradation of rhodamine B as a solid pollutant model and NO₂ as a typical gaseous pollutant was assessed on the surface of the acrylic-based coatings containing TiO₂/SiO₂ nanoparticles (TSC.La) under direct sunlight and accelerated weathering conditions and the results were compared with a P25-TiO₂ nanoparticle (UT.La) coated samples.

To evaluate the degradation of rhodamine B, color coordinates (L*, a*, and b*) were measured, while the degradation of NO₂ was determined in a batch-designed photocatalytic reactor by measuring the reduction in gas concentration. For the TSC.La sample exposed to accelerated weathering conditions, the changes in a* parameter (∆a*) were about 60%, which was 44 times greater than the changes in this parameter for the sample exposed to sunlight. The surface morphology of the exposed samples to the accelerated weathering conditions was evaluated using AFM and BET measurement. The AFM results indicated that TiO₂/SiO₂ nanoparticles lead to less surface degradation of the paints compared to the commercial TiO₂ nanoparticles. Steady-state NO₂ concentration decreased from 30 to 27 ppm, at a RH%<20, for UT.La and TSC.La samples in the reactor after 45 and 60 min of UV exposure, which are equivalent to photocatalytic power of ca 6-8 mLm^-2h^-1 for the two samples, respectively.

Keywords: NOx reduction, Photoactive acrylic, TiO2/SiO2 nanocomposite, Air purification.