A novel co-catalyzed system between persulfate and chlorite by sonolysis for removing triphenylmethane derivative

Abstract

Triphenylmethane (tpm) derivatives (e.g. tpmCV) have threatened the safety of the aquatic environment due to the potential toxicity and carcinogenicity. In this study, the novel ultrasonic/persulfate/chlorite (US/S2O82−/ClO2−) oxidation process was developed for the effective removal of tpmCV in wastewater. The apparent non-integer kinetics (n around 1.20) of tpmCV degradation under different factors (R2Adj > 0.990) were investigated, respectively. Inhibiting effects of anions were greater than those of cations (except Fe(II/III)). The adding of micromolecule organic acids could regulate degradation towards positive direction. The double response surface methodology (RSM) was designed to optimize tpmCV removal process, and the acoustic-piezoelectric interaction was simulated to determine the propagation process of acoustic wave in the reactor. The possible degradation pathway was explored to mainly include carbonylation, carboxylation, and demethylation. The estimated effective-mean temperature at the bubble-water interface was calculated from 721 to 566 K after introducing the ClO2−, however, the adsorption or partitioning capacity of tpmCV in the reactive zone was widened from 0.0218 to 0.0982. The proposed co-catalysis of US/S2O82−/ClO2− was based on the determined active species mainly including ClO2, SO4⋅−, and ⋅OH. Compared with other US-based processes, the operating cost (3.97 $/m3) of US/S2O82−/ClO2− with the EE/O value (16.8 kWh/m3) was relatively reduced.