Peicheng Huang,Weichun Yang,Varney Edwin Johnson,Mengying Si,Feiping Zhao,Qi Liao,Changqing Su,Zhihui Yang
The contamination of soils by mercury (Hg) seriously threatens the local ecological environment and public health. S-functionalized amendments are common remediation technology , yet, Hg re-activation often occurs in the commonly used immobilization remediation by S-functionalized amendments, resulting in an unsatisfactory remediation effect. In this study, a novel FeS–Se functionalized biochar composite (FeS-Se-BC) amendment was prepared and applied for the efficient remediation of Hg-polluted soil. An immobilization efficiency of 99.62% and 99.22% for H 2 O-extractable Hg and TCLP solution-extractable Hg was achieved with the application of FeS-Se-BC (0.05) after 180 d. The analyses of XPS, Hg-TPD, SEM-EDS demonstrated that excellent remediation performance by FeS-Se-BC resulted from the synergistic effect of FeS and Se to form HgS and HgSe concurrently. In comparison to the treatments of biochar and FeS-functionalized biochar (FeS-BC), FeS-Se-BC promoted the transformation of exchangeable, carbonate-bound, and Fe–Mn oxides-bound Hg fractions into organic material-bound, and residual fractions, effectively reducing the risk of Hg-contaminated soil from a highly dangerous level to a low risk. Furthermore, the introduction of Se clearly inhibited the re-activation of Hg and reduced the release of Hg by 81.12% compared to FeS-BC when the ratio of S 2− to Hg was 5: 1 due to the formation of extremely stable HgSe. These results suggest that FeS-Se-BC has good potential for remediation of Hg-polluted soils which provides a new inhibitory idea for Hg re-activation after immobilization.
The Fe–Mn–Ce/CP catalyst prepared by the incipient-wetness impregnation method was investigated for elemental mercury (Hg 0 ) removal in simulated coal-fired flue gas . The incorporation of Fe could remarkably enhance the SO 2 -resistance of Fe–Mn–Ce/CP catalyst at low temperature, and the existence of water vapor had negative impact on Hg 0 removal efficiency. More than 95% of Hg 0 could be removed at 100 °C under the conditions of 60 ppm HCl, 3% O 2 ( v/v ), 5% H 2 O ( v/v ) and 400 ppm SO 2 . Hg-TPD results indicated that Hg 0 adsorption amount decreased after the addition of H 2 O or SO 2 . The XPS results revealed that the incorporation of Fe could enhance the contents of high valence Mn x + (i.e., Mn 3+ /Mn 4+ ) and Ce 3+ species in the composite catalysts, which are favorable for the oxidation process of elemental mercury. The surface characteristics were not the primary factor determining the catalytic activity . Overall, the catalytic performance of the Fe–Mn–Ce/CP catalyst was closely related to the Fe 3+ state, high ratios of (Mn 4+ + Mn 3+ )/Mn 2+ and high content of not fully coordinated cerium species.
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