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In recent years, Hg re-emission from the wet scrubber has become a hot topic in the field of Hg abatement since wet scrubber has been considered as an effective way to remove Hg. In this paper, the effects of Cu ions on Hg re-emission were investigated for the first time in the presence of SO 3 2− . The effect of CuCl 3 2− was proved to directly reduce Hg 2+ to insoluble Hg 0 and to catalytically decompose Hg(SO 3 ) 2 2− to Hg 0 and SO 4 2− in the presence of SO 3 2− . When adding the Cu 2+ into solution with low concentration, Hg re-emission was increased due to the generation of Cu + from the reduction of Cu 2+ by SO 3 2− . Further increase of Cu 2+ concentration inhibited Hg re-emission, which was possibly owing to the formation of metal Cu which could absorb Hg 0 to form amalgam. The decomposition of Hg(SO 3 ) 2 2− by CuCl 3 2− and Cu + meet pseudo-first-order reaction with respect to Hg 0 and the activation energy parameters are 64.43 and 48.78 kJ/mol, respectively. Difference of electron transfer path in the decomposition of Hg(SO 3 ) 2 2− with Cu + was proposed to be the reason of low activation energy. [ABSTRACT FROM AUTHOR]

Recently, the mercury re-emission from the scrubbing solution has become a hot topic in wet flue gas desulfurization process (WFGD). Selenite is one of the most important matters in the solution. It is discovered that selenite have great effect on the mercury re-emission in the WFGD process in this paper. Several important parameters, such as selenite concentration, pH value, temperature and chloride concentration, and reaction mechanisms were studied on the Hg 0 re-emission. The experimental results indicate that mercury reduction and re-emission can be effectively inhibited with high selenite and chloride concentrations, low temperature and pH value. The mechanisms for inhibition of mercury reduction and re-emission are proved to be different under acid and alkaline conditions respectively. Under acid condition, it is the formation of stable HgSe that decrease Hg 0 re-emission. However, the formation of more stable HgSeO 3 SO 3 2 - or Hg ( SeO 3 ) 2 2 - than Hg ( SO 3 ) 2 2 - contributes to avoid the oxidized mercury reduction by sulfite ions and then the mercury re-emission under the alkaline condition. In addition, it is also found that Cl - ions can further enhance the inhibition effect and suppress Hg 0 re-emission by the formation of stable HgSeO 3 Cl - and HgSeO 3 Cl 2 2 - complexes. [ABSTRACT FROM AUTHOR]