Effect of copper ions on the mercury re-emission in a simulated wet scrubber

- CuCl32− ions could directly reduce Hg2+ to insoluble Hg0.
- CuCl32− ions play a catalytic role in the decomposition of Hg(SO3)22−.
- Low Cu2+ concentration could promote Hg0 re-emission due to the generation of Cu+.
- The Hg0 re-emission decreased due to the formation of metal Cu which could absorb Hg0 to form amalgam in high Cu2+ concentration.
- The addition of Cu ions change the electron transfer path of Hg(SO3)22−.

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 SO32−. The effect of CuCl32− was proved to directly reduce Hg2+ to insoluble Hg0 and to catalytically decompose Hg(SO3)22− to Hg0 and SO42− in the presence of SO32−. When adding the Cu2+ into solution with low concentration, Hg re-emission was increased due to the generation of Cu+ from the reduction of Cu2+ by SO32−. Further increase of Cu2+ concentration inhibited Hg re-emission, which was possibly owing to the formation of metal Cu which could absorb Hg0 to form amalgam. The decomposition of Hg(SO3)22− by CuCl32− and Cu+ meet pseudo-first-order reaction with respect to Hg0 and the activation energy parameters are 64.43 and 48.78 kJ/mol, respectively. Difference of electron transfer path in the decomposition of Hg(SO3)22− with Cu+ was proposed to be the reason of low activation energy.