Unraveling the thallium immobilization in CuO/PMS system

Abstract

Thallium (Tl) is a hypertoxic and high-mobile heavy metal in aquatic system of mineral deposits. Although Tl geochemically possesses chalcophilic character, little is known about the copper-bearing ores, such as cupric oxide (CuO), in terms of the adsorption behaviors of Tl cations. In this work, the hybrid processes and mechanisms of catalysis and adsorption of Tl(I) on CuO nanoparticles under peroxymonosulfate (PMS) catalytic system were comparatively examined, through empirical models (oxidation kinetics, adsorption kinetics, and adsorption isotherms), characterizations (HRTEM, XRD, EPR, and XPS), and independent gradient model based on Hirshfeld partition. CuO/PMS performed high oxidation rate (0.284 min−1) coupled with the maximum adsorption capacity (369.54 mg·g−1) to eliminate Tl(I) under the optimal conditions (400 mg·g−1 CuO, 1 mM PMS, and pH 10). 1O2 and OH functioned as the pivotal contributors for Tl(I) oxidation. Simultaneous adsorption of Tl(III) onto CuO comprised chemisorption, electrostatic attraction, and surface complexation. Tl(H2O)33+ hydrate equipped stronger van der Waals force and H-bond interaction to CuO (111) surface than Tl(H2O)2+ hydrate, which serves as the cornerstone for Tl(III) immobilization and detoxification. The discoveries provide a pioneering and promising comprehension of the interaction and destiny of Tl cations with copper-based ores.