Role of Sulfur Trioxide (SO 3 ) in Gas-Phase Elemental Mercury Immobilization by Mineral Sulfide

作者：Zequn Yang, Hailong Li, Wenqi Qu, Mingguang Zhang, Yong Feng, Jiexia Zhao, Jianping Yang, Kaimin Shih · 发表于：Environmental Science & Technology · 年份：2019 · DOI：10.1021/acs.est.8b07317 · 被引用次数：71 · 研究领域：Mercury impact and mitigation studies、Air Quality and Health Impacts、Toxic Organic Pollutants Impact

Mineral sulfide based sorbents were superior alternatives to traditional activated carbons for elemental mercury (Hg 0 ) immobilization in industrial flue gas. A systematical study concerning the influence of sulfur trioxide (SO 3 ) on Hg 0 adsorption over a nanosized copper sulfide (Nano-CuS) was for the first time conducted. SO 3 was found to significantly inhibit the Hg 0 removal over Nano-CuS partially because SO 3 oxidized the reduced sulfur species (sulfide) with high affinity to mercury to its oxidized sulfur species (sulfate). Moreover, a brand new “oxidation-reduction” mechanism that led to a simultaneous oxidation of sulfide and reduction of mercury on the immobilized mercury sulfide (HgS) was responsible for the inhibitory effect. Even though the released Hg 0 from the reduction of mercury in HgS could be oxidized by SO 3 into its sulfate form (HgSO 4 ) and recaptured by the sorbent, the “oxidation-reduction” mechanism still compromised the Hg 0 capture performance of the Nano-CuS because HgSO 4 deposited on the sorbent surface could be easily leached out when environmentally exposed. These new insights into the role of SO 3 in Hg 0 capture over Nano-CuS can help to determine possible solutions and facilitate the application of mineral sulfide sorbents as outstanding alternatives to activated carbons for Hg 0 immobilization in industrial flue gas.