Solar light assisted photocatalytic degradation of 1,4-dioxane using high temperature stable anatase W-TiO2 nanocomposites

This work outlines a systematic and detailed study of the modification of anatase TiO2 with tungsten (W). The impact this coupling has on the temperature of the anatase to rutile phase transition and the photocatalytic degradation of 1,4-dioxane, a highly toxic compound that is increasingly present in water bodies is also studied. TiO2 composite photocatalysts with 2, 4, 8 and 16 mol. % W, respectively, were produced using a sol-gel process and then calcined between 500−1000 °C. The crystallinity and phase composition of pure and W-TiO2 photocatalysts were examined using X-ray Diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). All W-TiO2 composite photocatalysts demonstrated 100 % anatase crystalline phase at calcination temperatures as high as 800 °C. Due to the retention of 26 % anatase after calcination at 950 °C, 8 mol. % W was established as the optimum W loading for the development of high temperature stable anatase W-TiO2 composite photocatalysts. The % anatase content also significantly impacts the photocatalytic activity of the W-TiO2 composite photocatalysts. In the presence of solar light, 100 % of 1,4-dioxane was successfully degraded by 2-W-TiO2, 4-W-TiO2 and 8-W-TiO2 composite photocatalysts, respectively, calcined at 800 °C. However, as the calcination temperature increases and the % anatase content decreases, only 70 % of 1,4-dioxane was degraded when using 4-W-TiO2 and 8-W-TiO2 calcined at 900 °C. The highest % removal of 1,4-dioxane was also achieved using 8-W-TiO2 calcined at both 800 and 900 °C. 8-W-TiO2 is therefore considered the optimum sample for both photocatalysis and phase transition temperature.