In situ acid etching boosts mercury accommodation capacities of transition metal sulfides

Transition Metal sulfides (TMSs) are effective sorbents for entrapment of highly polluting thiophiles such as elemental mercury (Hg-0). However, the application of these sorbents for mercury removal is stymied by their low accommodation capacities. Among the transition metal sulfides, only CuS has demonstrated industrially relevant accommodation capacity. The rest of the transition metal sulfides have 100-fold lower capacities than CuS. In this work, we overcome these limitations and develop a simple and scalable process to enhance Hg-0 accommodation capacities of TMSs. We achieve this by introducing structural motifs in TMSs by in situ etching. We demonstrate that in situ acid etching produces TMSs with defective surface and pore structure. These structural motifs promote Hg-0 surface adsorption and diffusion across the entire TMSs architecture. The process is highly versatile and the in situ etched transition metal sulfides show over 100-fold enhancement in their Hg-0 accommodation capacities. The generality and the scalability of the process provides a framework to develop TMSs for a broad range of applications. There is an urgent need to develop efficient strategies to remove elemental mercury from industrial flue gases. Here the authors develop a simple, versatile, and scalable strategy to obtain a 100-fold enhancement of the elemental mercury accommodation capacities of a wide range of transition metal sulfides by in situ acid etching.