Rapid and Selective Removal of Hg<sup>2+</sup> by Copper Sulfides under Strongly Acidic Conditions: Mechanism, Kinetics, and Its Application in Recovering Hg from Waste Acids of Smelters
Shuai Chang, Pengjian Lv, Ruiyang Qin, Jian Mei, Qianqian Hong, Shijian Yang
Abstract
In this study, CuS x /TiO 2 was developed to selectively remove Hg 2+ from waste acids. X-ray photoelectron spectroscopy and X-ray diffraction analyses demonstrated that there were two reaction routes for Hg 2+ removal by CuS x /TiO 2, corresponding to the two types of copper sulfides (i.e., CuS and Cu 2 S). The CuS route with the product HgS occurred regardless of the presence of Cl –, while the Cu 2 S route with the product Hg 2 Cl 2 only occurred with Cl – . Therefore, Cl – exhibited a remarkable promotion on Hg 2+ removal. Kinetic analysis demonstrated that the CuS route was markedly faster than the Cu 2 S route, which accounted for the rapid removal of Hg 2+ . CuS x /TiO 2 showed excellent performance for Hg 2+ removal at pH 2.0 with an adsorption rate of 16.3 mg g –1 min –1, and removed Hg 2+ can be recovered as liquid Hg 0 as a co-benefit of Hg 0 recovery units in smelters. Therefore, CuS x /TiO 2 was a promising sorbent for Hg 2+ recovery in waste acids for centralized control.