The Photocatalytic Oxidative Stress on the Transport Transformation Of Heavy Metals And As in Lead-Zinc Smelting Slag

Abstract

Pollution of heavy metals in lead-zinc (Pb-Zn) smelting slag is a universal environmental problem. The weathering and toxic leaching behavior of Pb-Zn smelting slag under strong ultraviolet (UV) radiation especially in plateau area are rarely reported. The interaction process between heavy metals (HMs) and minerals in Pb-Zn smelting slag under the strong sunlight radiation is not clear. Herein, the oxidative stress process of HMs-Melite-pyrite in Pb-Zn smelting slag under natural environment was simulated for the first time. Interestingly, UV as the energy source, pyrite is excited, promote electron migration e- and h+ generation, resulting in xidation-reduction reactions, Reactive Oxygen Species (ROS) act as intermediates to convert As3+ to the more stable As5+. Due to the difference in the symbiotic relationship, the Pb containing mineral (galena) is directly oxidized to PbSO4 by ROS (H2O2), resulting in the toxic leaching rate of Pb increased by 12.4% and 29.3%. The final acceleration of Zn release (3.5% and 21.1%). This study provides a new approach to understand the migration and transformation behavior of HMs in Pb-Zn smelting slag.

Keywords: UV radiation, Pb-Zn smelting slag, Oxidation-stabilization, Dissolution release