Orthogonal experimentation for optimization of TiO2 nanoparticles hydrothermal synthesis and photocatalytic property of a TiO2/concrete composite

Abstract

An orthogonal experimental design was applied to optimize the hydrothermal preparation parameters of TiO₂ nanoparticles by the analysis of means (ANOM) and variances (ANOVA). The ANOM & ANOVA results on crystalline and size show that the optimal process of synthesized TiO₂ nanoparticles is 5.0% TBT, an alkalescent environment (pH = 9), 160 °C reaction temperature, and 3 h reaction time. The main factors affecting the photocatalytic properties of TiO₂ nanoparticles were explored by measuring the UV light absorbance index, and the results show that their photocatalytic performance are excellent when methyl orange (MeO) concentration is 2.5 mg L⁻¹, the pH value is 6, and the Ag-doped amount is 5.0%. Then optimal TiO₂ nanoparticles aqueous suspensions with varied concentration (c_TiO2) were sprayed on permeable concrete to fabricate TiO₂/concrete composites, and their photocatalytic activity was evaluated by measuring the degradation rate of soaked MeO along the UV radiation time. It is concluded that when c_TiO2 is 2.0 g L⁻¹ with above fixed conditions, the produced TiO₂/concrete composite has an optimal capacity (35.7%) in the photo-degradation of azo pollutants.