Coal gasification slag as mineral carbon-based catalyst for persulfate degradation of binary endocrine disruptors: Performance and mechanism

Coal gasification fine slag (CGFS) is a carbon-rich industrial solid waste featured with rough, porous surface and abundant inorganic minerals, facing significant utilization challenges. This study systematically investigated the potential of CGFS as a mineral carbon-based catalyst to activate peroxydisulfate (PDS) for degrading binary bisphenol A (BPA) and tetrabromobisphenol A (TBBPA). Under optimal conditions of 0.10   g/L PDS, 0.20   g/L CGFS, pH 7.0 and 30 °C, the CGFS-activated PDS system completely degraded binary BPA and TBBPA within 2   h, achieving a mineralization efficiency of over 53.8%. The presence of polar groups and defects in CGFS was beneficial for its adsorption, while surface moieties such as oxygen-containing functional groups and graphite carbon domains mediated PDS activation. The catalytic degradation process involved radical (•OH, SO 4 •- and O 2 •- ) and non-radical ( 1 O 2 ) pathways, which substantially contributed to the transformation of binary contaminants. Liquid chromatography-mass spectrometry identified degradation intermediates, and ECOSAR assessment indicated their lower ecotoxicity compared to the parent compounds. The practical biotoxicity of the degradation system was tested using Escherichia coli . Heat treatment effectively regenerated CGFS for reuse, and its good adaptability to actual water bodies demonstrated its great potential for practical application. This study elucidates the simultaneous degradation mechanism of BPA and TBBPA via CGFS-activated PDS system. This pioneering approach offers a cost-effective solution to treat BPA/TBBPA-containing wastewater and opens up new possibilities for CGFS recycling.