Novel Acceleration of Partial Transformation of CuS on Fe2TiO5 to Cu2S for the Selective Adsorption of Hg2+ from Waste Acids: Performance, Kinetics and Mechanism

In this work, magnetic CuS/Fe2TiO5 was developed to selectively adsorb Hg2+ from the waste acids. The partial transformation of CuS on Fe2TiO5 to Cu2S by thermal treatment displayed a novel acceleration on Hg2+ adsorption, and the initial Hg2+ adsorption rate increased by approximately 12.7 times. Two reaction pathways for Hg2+ adsorption were identified: CuS reacted with aqueous Hg2+ to form Hg3S2Cl2, and Cu2S reacted with aqueous Hg2+ to form HgS. The kinetic analysis demonstrated that the accelerated Hg2+ adsorption was primarily attributed to the CuS route, due to improved physical adsorption of HgCl2, rather than the addition of the Cu2S route. As CuS/Fe2TiO5-300 exhibited excellent performance for Hg2+ adsorption, with an initial rate of 0.140 mmol g-1 min-1, a capacity of 483 mg g-1, and a selectivity of 100%, it was a promising sorbent to selectively adsorb Hg2+ from waste acids for the centralized control.