Synergistic effects of α-Fe2O3-TiO2 and Na2S2O8 on the performance of a non-thermal plasma reactor as a novel catalytic oxidation process for dimethyl phthalate degradation

This study aims to evaluate the synergistic effect of alpha-Fe2O3-TiO2 nanocomposite and Na2S2O8 as the process enhancers for a non-thermal dielectric barrier discharge plasma reactor (NTP-DBD). Dimethyl phthalate (DMP), a priority and hazardous pollutant, was selected as the target pollutant to evaluate the efficacy of the studied catalytic process. A central composite design was used to determine the effects of model parameters including reaction time (x(1)), pH (x(2)), Na2S2O8 (denoted as persulfate) concentration (x(3)), alpha-Fe2O3-TiO2 nanocomposite concentration (x(4)), and applied voltage (x(5)). Among linear, quadratic, and interaction terms, the most effective factors were reaction time (x(1)), pH (x(2)(2)), and the interaction between pH and persulfate concentration (x(2):x(3)), respectively. According to optimization results, the complete degradation of DMP can be achieved at: reaction time of 5.2 min, an applied voltage of 14 kV, pH equal to 3, persulfate concentration of 2 mM.L-1, and nano-composite concentration of 1 g.L-1, while the single plasma process required about 19.4 min of reaction time. This study can demonstrate that the heterogeneous addition of alpha-Fe2O3-TiO2 nanocomposite coupled with persulfate into the NTP-DBD reactor could enhance the oxidation rate and potential of the studied process with their catalytic and synergistic effects.