Revestimento de partículas de TiO2 pelo método de ultrassom para aplicação em protetor solar

Abstract

TiO2 is a common inorganic filter used in sunscreens and it has the propriety of scattering, reflect and absorb the ultraviolet radiation. TiO2 particles need a coating to increase its dispersion in sunscreen products and resist the formation of particle agglomerations, influencing stability and aesthetics of the final product as well as reducing its photocatalytic activity. Therefore, the objective of the present study was to coat particles of commercial TiO2, evaluate its stability, photocatalytic activity without loss of UV protection, for application in sunscreens. The methodology used for the coating was based on ultrasonic radiation and TiO2 was coated with SiO2, Al2O3, ZrO2, citrate, and sodium polyacrylate. X-Ray Diffraction (XRD) technique was used to characterize the materials, where it was possible to identify the rutile phase in the coated samples. X-ray fluorescence, Fourier-transform infrared spectroscopy (FTIR) and Thermogravimetry confirmed the coatings in TiO2/SiO2, TiO2/Al2O3, TiO2/ZrO2 e TiO2/PAANa. Scanning Electron Microscopy (SEM) determined the particle size of the samples. According to Zeta Potential (ξ) and Dynamic Light Scattering (DLS), the change in the surface loads of the samples after the coatings was verified, with better stability of TiO2/SiO2 and TiO2/PAANa. All coated TiO2 particles produced, in relation to the commercial TiO2 (TiO2-COM) presented similar UV protection and showed a lower photocatalytic activity. The sunscreens containing the coated TiO2 particles were produced, where the sun protection factor (SPF), the ξ potential and DLS of the formulations were evaluated, where all the samples presented similar FPS, with TiO2/PAANa being the one with the best stability.