Synergistic Degradation Of Aqueous Diuron And Atrazine By Dielectric Barrier Discharge Plasma And TiO₂/ACF

Dielectric barrier discharge plasma is an advance oxidation technology which can produce the UV radiation and various active species. The organic compounds can be transformed into carbon dioxide and water by dielectric barrier discharge plasma. As the carbon material, TiO2/ACF has the high photocatalysis and adsorption ability due to their high specific surface area and high chemical stability. Removal of diuron and atrazine with dielectric barrier discharge plasma coupled with TiO2/ACF was conducted, and the synergistic removal mechanism was studied.Firstly, efficient adsorption of diuron and atrazine with TiO2/ACF was explored in this study. The results showed that the pseudo-second-order kinetic model was more suitable to describe the adsorption of diuron and atrazine onto TiO/2ACF. The sorption data could be well interpreted by the Langmuir model. And the adsorption behavior is a spontaneous endothermic reaction.Secondly, the efficient removal of diuron and atrazine with dielectric barrier discharge plasma was explored in this study. The results showed that incearsing the input power was favorable for the removal of diuron and atrazine. The removal rate of diuron and atrazine increased with increasing air flow rate and initial pH, and decreased with increasing initial concentration. The generated OH?·O?·H? H2O2 and O3 played an important role in the removal of diuron and atrazine. The acute toxicity of diuron and atrazine sample firstly increased and then decreased with increasing discharge time. The value of pH and TOC decreased with increasing discharge time. The degradation byproduct and the removal mechanism of diuron and atrazine were proposed according to the analysis of LC-TOF-MS.The degradation pathways of diuron might be formed mainly in dechlorination hydroxyl and alkyl oxidation reactions. The degradation pathways of atrazine might be formed mainly in dechlorination hydroxylation, alkyl oxidation, dechlorination hydroxylation combined with alkyl oxidation and demethylation oxidation reactions.Finally, the efficient removal of diuron and atraizne with dielectric barrier discharge plasma synergistic TiO2/ACF was explored in this study. The results showed that when the input power was 50 W, the removal rate of diuron and atrazine increased with increasing initial concentration and air flow rate. The acute toxicity of diuron and atrazine sample firstly increased and then decreased with increasing discharge time. The removal rate of TOC was increased and the pH value was decreased during the discharge. The removal rates of diuron and atrazine in synergistic discharge system were higher than those in individual discharge system. The degradation byproduct and the removal mechanism of diuron and atrazine in synergistic discharge system were proposed according to the analysis of LC-TOF-MS. The synergistic degradation pathways of diuron were demethylation, deamination, methyl oxidation, demethylation hydroxyl, aldehyde hydroxyl, aldehyde oxidation, demethylation combined with hydroxyl, dechlorination hydroxyl and dechlorination hydroxyl combined with methyl oxidation reactions. The synergistic degradation pathways of atrazine were dechlorination, dechlorination hydroxyl, alkyl oxide and alkyl, methyl oxidation, hydroxyl, dechlorination hydroxyl combined with demethylation and demethylation, alkyl oxidation reactions. The degradation degree of diuron and atrazine in synergistic discharge system was higher than that in individual discharge system. Compare with the FT-IR, XRD, XPS and SEM of TiO2/ACF before and after synergistic discharge, it was found that little changes on TiO2/ACF were observed, which meaned the structure of TiO2/ACF prepared in this experimental was stable.