Gaseous Elemental Mercury Capture by Magnetic FeS₂ Nanorods Synthesized via a Molten Salt Method

Coal burning emits a significant amount of elemental mercury (Hgo) into the atmosphere, which can cause severe damage to the environment and human health. Here, magnetic FeS2 nanorods are facilely obtained via a low-temperature (200–350 °C) molten salt (KSCN) route. The annealing temperature is found to notably affect the structure and Hgo capture performance of FeS2, while precursors exert subtle effects on the mercury adsorption performance. The Hgo capture ability of FeS2 first increases and then decreases with increasing annealing temperature. The highest magnetism (12 emu/g) and optimal mercury capture performance (Hgo removal efficiency of 96.2%) are achieved over FeS2 nanorods synthesized at 250 °C. This material shows superior performance in the temperature range of 60–180 °C owing to its rod-like structure with ample number of exposed adsorption sites. NO and SO2 are found to only slightly intervene in the mercury removal process. Hgo vapor first adsorbs on the FeS2 surface via physical adsorption followed by conversion into mercury sulfide (HgS) and mercury oxide (HgO) by the oxidation of disulfide ions (S22–) and chemisorbed oxygen (O*) species, respectively.