Synergy between fayalite-constituted waste copper smelting slag and hydroxylamine: An efficient combination for construction and application of a surface Fenton system in removal of mining organic pollutants

The growing problem of typical organic pollution in mines, and the effective utilization of increasing mine industrial wastes have been the most challenging issues in the current global situation. In this study, copper smelting slag (CSS), hydroxylamine (HA) and H2O2 were employed to construct an efficient surface heterogeneous catalyst for the degradation of organic pollutants in mines. Fayalite and its ≡Fe were proved, by multiple methods, to be the crucial ferriferous catalyst in the CSS. HA greatly increased the oxidation effectiveness of the CSS from 53.6% to ∼100% by regulating the Fe2+/Fe3+ circulation within the fayalite lattice. Due to the special structural configuration of iron atoms in fayalite, the surface generation rate of •OH catalyzed by CSS was 101-106 times higher than in other iron-bearing minerals. •OH was demonstrated to be the main active radical species, and as an intermediate, O2•- also had a role in the oxidation process. In the presence of low doses of Cr, a synergistic removal of organic pollutants occurred, dominated by the electron transfer. Accordingly, this study proposes both, a new design concept for recycling the industrial solid waste from mines and a new surface catalyst system for the removal of organic pollutants from mining.