Alkali-thermal activated persulfate treatment of tetrabromobisphenol A in soil: Parameter optimization, mechanism, degradation pathway and toxicity evaluation

Abstract

The continued accumulation of halogenated organic pollutants in soil posed a potential threat to ecosystems and human health. In this study, tetrabromobisphenol A (TBBPA) was used as a typical representative of halogenated organic pollutants in soil, for alkali-thermal activated persulfate (PS) treatment. The results of response surface methodology (RSM) showed a optimal debromination efficiency of TBBPA was 88.99 % under the optimum reaction conditions. Quenching experiments and electron paramagnetic resonance (EPR) confirmed that SO4−•, HO•, O2−• and 1O2 existed simultaneously in the oxidation process. SO4−• played a major role in the initial stage of the reaction, and O2−• played a major role in the the last stage. Based on density functional theory (DFT) and intermediate products, two degradation pathways were proposed, including debromination reaction and β bond scission. Moreover, the basic physical and chemical properties of the soil were affected to a certain extent, while the soil surface structure, elements and functional group composition rarely changed. In addition, the T.E.S.T. analysis and biotoxicity tests proved that alkali-thermal activated PS can effectively reduce the toxicity of TBBPA-contaminated soil, which is conducive to the subsequent safe secondary utilization of soil.