Mechanochemical force driven activation of endogenous iron species in coal gasification fine slag for oxidative removal of phenolic pollutants.

Coal gasification fine slag (CGFS) is a kind of solid waste with large output in the coal chemical industry, which contains rich aluminosilicate minerals and residual carbon. A magnetic composite (Fe-MCGFS-800) was prepared from CGFS via the mechanochemical method, enabling the migration and transformation of endogenous iron species within the system. The composite, with an effective active iron species content as high as 34 %, demonstrated excellent performance in the removal of bisphenol A (BPA) in the peroxymonosulfate (PMS) system. The Fe-MCGFS-800 could achieve a 93.1 % removal rate of BPA within 60 min, with a kinetic reaction rate of 0.0418 min-1. Characterization results indicated that Fe-MCGFS-800 possessed a rich mesoporous structure, where aluminosilicate minerals and the carbon substrate were interlaced, providing a stable structure for the effective removal of BPA. The ketone group structure and abundant iron species in Fe-MCGFS-800 could activate PMS to generate reactive oxygen species (ROS), which played a dominant role in the BPA degradation process. Specifically, the bondage of iron species could be broken by the mechanochemical method, and this method promoted the phase transformation and the formation of active centers. Moreover, the migration of iron species enhanced the electron-transfer ability, promoting the degradation of BPA through non-radical pathways. Therefore, the magnetic Fe-MCGFS-800 prepared from CGFS is a potential high-efficiency catalytic material for PMS activation. It provides a convenient method and novel insights for the utilization of CGFS-derived catalytic materials and the large-scale application of CGFS.