Stepwise Ions Incorporation Method for Continuously Activating PbS to Recover Mercury from Hg-Rich Flue Gas.

Transition metal elements doping is a conventional strategy for the modification of sulfide-based sorbents to obtain preferable Hg adsorption capability. One problem was that such a method could only obtain a temporary promotion to sulfides. To achieve continuous promotion of mercury capture performance, we use the difference of solubility product () between sulfides to develop a postsynthesis approach for stepwise doping of PbS by Cu ions. Moreover, it further demonstrated the restoration of PbS surface under a given high temperature, enabled by thermal migration of the foreign Cu ions from outer to interlayer in PbS lattice and rereleased of S sites occupied previously by mercury. The Hg adsorption capacity of PbS was enlarged from 0.86 to 2.76 mg·g after the first doping, resulting from the mild oxidization of S to S in the surface layer by foreign Cu ions. Furthermore, regeneration of spent PbS can be implemented by stepwise Cu incorporation due to the renewability of the surface, enabling even better Hg adsorption capacity after six cycle tests. This stepwise incorporation method promises the precise utilization of doped elements, as well as offers a tutorial example for the activation and regeneration of sulfide sorbents to recover Hg from Hg-rich flue gas.