Photocatalytic degradation of benzene-toluene gaseous mixture using N, Fe-TiO₂ photocatalyst under visible light: Response surface methodology (RSM) and artificial neural network (ANN) modelling / Arman Sikirman

Volatile organic compounds, VOCs such as benzene and toluene are hazardous to human health even when exposed at low concentration due to their carcinogenic impact. Recently, photocatalytic degradation has received great attention from researchers as one of the promising method to lower VOC concentration in the air. Common photocatalyst used for this process is titanium dioxide, TiO₂. However, TiO₂ can only be activated under UV light range due to the wide band gap energy. Limited resources are the challenge faced in implementing photocatalytic degradation. This is because only 3% of the sunlight wavelength range is of UV light while the other 45% is of visible light. The conventional method, also known as the ‘one-factor-at-a-time’ is a common approach taken in photocatalytic degradation. This approach is usually difficult and the interaction between process parameters is complicated to interpret as it requires numerous experiments. Besides, the complexity of photocatalytic degradation also lies in predicting the removal efficiency of the pollutants. Hence, this study is attempted to modify the TiO₂ photocatalyst and to activate it under visible light wavelength range. The modified photocatalyst was applied in the photocatalytic degradation of individual benzene or toluene, as well as their gaseous mixture under irradiation of visible light. In this research, TiO₂ was modified by co-doping with nitrogen and iron elements, prepared using sol-gel method in order to activate the photocatalyst in visible light wavelength. The modified photocatalyst was characterized using XRD, BET surface area, UV-Vis DRS, and XPS. The synthesized N, Fe- TiO₂ was applied in the photocatalytic degradation, and tested with individual benzene or toluene, and benzene-toluene gaseous mixture under irradiation of visible light. To reduce the number of experiments, as well as to optimize the degradation process, response surface methodology (RSM) was applied for each photocatalytic degradation cases…