S-Fe/Co@GC reduction-oxidation sequential reaction system for the high-efficiency mineralization of...

The lipophilic, bioaccumulative, persistent nature of Tetrabromobisphenol A (TBBPA) contributes to its widespread detection in various environmental media, posing significant negative implications for the living environment and human health. In this study, a reduction system and a reduction-oxidation sequential reaction system were developed using a magnetic core-shell bimetallic amendment (S-Fe/Co@GC) to investigate the degradation and mineralization properties of TBBPA. Additionally, the degradation mechanism and degradation pathway of TBBPA in various systems were analyzed. In the sole S-Fe/Co@GC reduction system, sulfurized nano-zero-valent iron (S-Fe) and Co⁰ exhibited remarkable reductive capabilities towards TBBPA. The reaction of S-Fe/Co@GC gradually facilitated the debromination of TBBPA, ultimately leading to its conversion into bisphenol A. The reaction process demonstrated the synergistic effect among S-Fe, Co⁰, and graphite carbon, leading to a remarkable enhancement in the reduction performance of the material. Consequently, TBBPA removal efficiency reached 97.5% within a time frame of 10 h. In the reduction-oxidation sequential reaction system, the debromination of TBBPA during the reduction stage enhanced the subsequent oxidation stage's total organic carbon (TOC) removal rate. During the oxidation stage (0.03 mmol of PMS added at 30 min), TBBPA underwent attack by sulfate radical (SO₄·^-), hydroxyl radical (·OH), superoxide radical (O₂·^-), and singlet oxygen (¹O₂), leading to cleavage and opening of its structure. This process resulted in the conversion of TBBPA into short-chain fatty acids, ultimately mineralizing it into CO₂ and H₂O. Thus, this degradation pathway mitigated potential environmental risk associated with intermediates. The final TOC removal rate significantly increased to 72.7% when the dose of composite material was set at 1.0 g/L, surpassing that achieved by the conventional advanced oxidation system. Hence, the S-Fe/Co@GC reduction-oxidation sequential reaction system provides a new strategy for treating high-concentration TBBPA-contaminated water.