Effects of environmental factors and synthesis conditions on the photocatalytic activity of titanate nanotubes for removal of gaseous formaldehyde

Abstract

The increase in indoor air pollution problems stimulates the necessity for the development of photocatalytic removal processes, especially for the application of new and effective photocatalysts. In this study, we aimed to prepare and modify various types of titanate nanotubes (TNTs) synthesized by hydrothermal method and apply them for the removal of indoor formaldehyde by photocatalysis. The effect of environmental factors such as inlet concentration, exposed surface area, residential time, light intensity, and catalyst amount was investigated. The effects of various synthesis conditions such as acid treatment (i.e., at pH 1–9) and heat treatment (i.e., at temperatures of 120–900 °C) on the properties and the photocatalytic activity of the TNTs materials were also determined. Preliminary results showed that the highest removal efficiency of around 99% was found at the condition of 2 UV light bulbs, 29 s for retention time, 0.11 g of TNTs, 15 mg/m3 of formaldehyde, and 3 glass substrates. Regarding the synthesis condition, the TNTs material treated at pH 1.6 and annealed at 400 °C had the highest formaldehyde removal efficiency, which could be due to the suitable condition of mixed nanorods and nanotubes structure, anatase crystallinity, surface area, sodium content, and surface acidity the material.