Study of photocatalytic activity of nano and micro particles of ZnO compared to TiO2 applied on exterior surfaces cementitious building: Phase II.

Abstract

The aim of this study is to propose a continuity of the study of the photo catalytic activity of ZnO compared to n-TiO2P25 realized at FAPESP Process: 2013/06822-2, finished in 28.04.2016, after 30 months. It is intended to measure the photo catalytic activity of micro and nano particles of ZnO and TiO2, from different sources. Both particles were characterized by morphology (texture), chemical and mineralogical composition and the photo catalytic activity determined by the degradation of dyes such as methylene blue, which is a bacteriological dye difficult to degrade, with different exposure time and ultraviolet radiation. Test samples with higher efficiency in this test will be chosen to continue the study. The photo catalytic effect of these particles also will be evaluated in cementitious paint, with 4 and 8% addition of these oxides, applied on cementitious specimens will be exposed to natural weathering in 3 aging sites, urban, rural and marine environments. Besides, accelerated exposure tests will be done on specimens, coated with cementitious paint with the addition of these oxides, by exposure to A and B ultraviolet radiation and high humidity. Specimens painted with the cementitious paint, without addition of nano or micro particle, will be used as reference. The maintenance of the properties along time will be observed every 6 months by visual inspection, color and reflectance determined by instrumental equipments as well as observation of the presence of dirt and biological organism growth. (AU)