One Step Interface Activation of ZnS Using Cupric Ions for Mercury Recovery from Nonferrous Smelting Flue Gas.

The flue gases with high concentration of mercury are often encountered in the nonferrous smelting industries and the treatment of mercury-containing wastes. To recover mercury from such flue gases, sorbents with enough large adsorption capacity are required to capture and enrich mercury. ZnS is a cheap and readily prepared material, and even can be obtained from its natural ores. In this work, a simple controllable oxidation method-soaking in cupric solution-was developed to improve the interfacial activity of ZnS and its natural ores for Hg0 adsorption. The gaseous Hg0 adsorption capacity of ZnS was enhanced from 0.3 to 3.6 mg·g-1 after such treatment. Further analysis indicated that a new interface rich in S1- ions was formed and provided sufficient active sites for the chemical adsorption of Hg0. In addition, the cyclic Hg0 adsorption and recovery experiments demonstrated that the adsorption performance of spent activated-ZnS was recovered after reactivating sorbents with Cu2+, indicating the recovery of activated interface. Meanwhile, the high concentration of adsorbed mercury at the surface can be collected using a thermal treatment method. Utilization of raw materials from a zinc production process provides a promising and cost-effective method for removing and recovering mercury from nonferrous smelting flue gas.

Morphology-controlled synthesis and sulfur modification of 3D hierarchical layered double hydroxides for gaseous elemental mercury removal.

Porous structure and effective active site are beneficial for gaseous elemental mercury (Hg0) capture. Two kinds of hierarchical porous layered double hydroxides (LDHs) were synthesized through an in-situ growth method. Sulfur was used for the modification of these LDHs to enhance Hg0 removal performance. Two as-prepared NiAl-S4@SiO2 microspheres displayed three-dimensional morphologies, accordingly exhibited as core-shell and urchin-like morphologies. XRD, BET, FTIR, TEM and SEM were employed to investigate the structure effect on Hg0 uptake. The results indicated that after S-modification, the Hg0 removal efficiencies as well as SO2 resistance were enhanced. The Hg0 removal performances follow the order of: NiAl-S4@SiO2-urchin > NiAl-S4@SiO2-core at 100 °C. The mechanism for Hg0 removal was discussed based on the results of TPD, EDX and XPS. The porous structure of NiAl-S4@SiO2 composite was beneficial for gas transformation and intercalated [S4]2- ions were favorable for mercury uptake. The polysulfide combined with adsorbed mercury and formed HgS. Such materials exhibit promising potential for mercury uptake from SHg mixed flue gas.