Influence of organic acids on the phases and physical characteristics of titanium dioxide synthesized by sol–gel for air depollution through heterogeneous photocatalysis

BACKGROUND Air pollution in big cities is becoming a global problem due to its negative consequences on human health and the ecosystem. Currently, some materials available promise successful gases pollutants removal, by reacting with them through photocatalysis when sunlight irradiates them. The most studied and applied material is TiO2; due to its chemical stability and availability, it is widely incorporated into cements, bricks, coatings, etc. RESULTS In this study, powders of titanium dioxide were synthesized through the sol–gel method using tetraisopropoxide with and without organic acids. Their photocatalytic activity was determined by the colorimetric method, following the standard UNI‐11259, and by the NO abatement test using the international standard ISO‐22197‐1. The results of the colorimetric test indicate that all the samples are photoactive according to the criteria stablished in the standard. Additionally, a similar photocatalytic performance was evidenced in the NO abatement tests for all the samples despite the differences in their particle sizes and in their crystalline phase distributions obtained without and with the different organic acids used in the synthesis process. CONCLUSION The particles synthesized show that the use of organic acids influences the decrease in particle size; moreover, in the case of citric acid, a favourable effect on the appearance of the rutile phase is perceived. All the samples were photoactive and their photocatalytic performance, evaluated under a NO atmosphere, were not negatively affected by the largest particle size (150 nm) nor by the rutile phase content (42 wt.%). © 2022 Society of Chemical Industry (SCI).