Effect of Process Parameters on the Microstructure and Performance of TiO₂-Loaded Activated Carbon

In this study, the visible-light-driven photocatalytic regeneration performance of TiO₂-loaded activated carbon (TiO₂/AC) was effectively improved. By carefully controlling the activation condition at 700 °C for 2 h with a 60% H₃PO₄ concentration and 3:1 TBT (tetrabutyl titanate) impregnation ratio, 90.5% of methylene blue (50 mg/L) was removed within 2 h by a low-dose TiO₂/AC (0.5 g/L), which was much higher than those obtained in previous studies on TiO₂/AC. Moreover, the effects of process variables on the microstructure and performance of TiO₂/AC were systematically investigated. The results showed that (1) the long period of activation time effectively inhibited the photogenerated charge carrier recombination and enhanced the regeneration performance of samples; (2) the photogenerated charge carrier recombination rate was lowered initially and then increased as the temperature ascended, whereas the pore volume showed an opposite variation tendency, and thus the adsorption and regeneration performances of samples were improved at 500-700 °C and then weakened at 800 °C; (3) the increase of H₃PO₄ concentration effectively inhibited the charge carrier recombination and had an improvement in the adsorption and regeneration performances of samples; and (4) the photogenerated charge carrier recombination rate and bandgap value of samples decreased initially and then increased with increasing TBT mass ratio, so the regeneration performances of samples were improved initially and then lowered.