Enhanced removal of roxarsone and inorganic arsenic using ball-milled heating pad waste to activate peroxymonosulfate: Critical role of non-radical pathways.

[Display omitted] • Resource recovery and application of iron-containing heating pad waste are realized. • BM-HPW/PMS system achieved simultaneous removal of ROX and inorganic arsenic. • Ball milling modification catalyst improved the removal efficiency of ROX. • Non-radical pathway dominated the degradation of ROX in the BM-HPW/PMS system. The simultaneous removal of roxarsone (ROX) and inorganic arsenic was achieved by designing a heterogeneous catalytic system. In this study, iron-rich heating pad waste (HPW) was modified by ball milling (BM), and a BM-HPW activated peroxymonosulfate (PMS) system was constructed to control ROX pollution. Results show that during the ball milling process, Fe0 and Fe 3 O 4 crystalline phases were formed, and the surface area of the material got improved. BM-HPW/PMS system performed effectively in ROX degradation and inorganic arsenic adsorption. Sulfate radical (SO 4 −), surface-bound species, singlet oxygen (1O 2) and Fe(IV) were generated in the BM-HPW/PMS system, and the surface-bound species played a dominant role in ROX degradation. In addition, the possible degradation pathways of ROX were proposed according to the detected intermediates. This study adopted a green and environmentally-friendly mechanochemical method to achieve the recycle application of waste iron resources, which provides a new insight for PMS activation in water treatment. [ABSTRACT FROM AUTHOR]