Plasma-photocatalytic degradation of gaseous toluene using SrTiO3/rGO as an efficient heterojunction for by-products abatement and synergistic effects

In this study, toluene degradation was studied in a combined plasma-photocatalytic system using the SrTiO3/rGO as photocatalyst. The photocatalyst was combined with Non-Thermal Plasma (NTP) to improve the performance of NTP in terms of increased toluene removal efficiency (RE) and lower by-products formation. SrTiO3/rGO was synthesized through the simple hydrothermal method and characterized by XRD, FESEM-EDX, UV-vis DRS, and FTIR. Toluene degradation was performed in dynamic mode taking into account the effects of gas flow rate, toluene concentration, relative humidity (RH), and discharge power on the toluene RE. Interactions between the process parameters and optimization of the toluene removal in the plasma-photocatalytic system were investigated by central composite design (CCD). Results showed that Maximum RE of 100 % was obtained at 0.3 L/min flow rate, 61 % RH, 100 ppm initial concentration, and 291 w discharge power. An excellent synergistic effect was observed by combining the NTP with SrTiO3/rGO so that the toluene RE in the NTP-Photocatalytic system at 187.5 w discharge power was almost equal to RE obtained at 292 w discharge power in the NTP alone system. The introduction of SrTiO3/rGO also removed the organic by-products (benzaldehyde, benzoic acid, formic acid, and acetic acid) produced by NTP and improved the CO2 selectivity.