中文摘要：

湿法脱硫系统对燃煤电站烟气中的Hg2＋具有良好的脱除作用,但Hg2＋在脱硫系统内会被还原变为Hg0再次释放,造成汞的二次污染。本文系统研究了不同pH值条件下,温度、SO32-浓度以及O2浓度对Hg2＋的还原再释放的影响。实验结果表明：相同pH值条件下,温度的升高会极大地促进Hg2＋的还原释放,溶液中SO32-离子浓度的增大会与Hg2＋反应生成Hg（SO3）22-从而抑制了Hg2＋的还原;pH降低会造成配合物HgSO3的质子化,促进Hg0的再释放。O2的存在会破坏Hg（SO3）22-的稳定性,并且O2浓度越高这种破坏作用越明显,从而增强Hg2＋的还原再释放。同时,在较高pH值环境下,溶液中SO42-含量较高进而抑制Hg2＋的释放。

英文摘要：

The wet flue gas desulphurization（WFGD） system could effectively remove Hg2＋ from coal combustion flue gas.However,the Hg2＋ couldbe reduced in WFGD system,resulting in Hg0re-emission.In this work,the interaction between Hg2＋ and SO32- in aqueous phase was studied by means of controlling the pH value.The operating temperature,the concentration of SO32- and O2 were investigated.The experiment results indicated that the Hg2＋ reduction was promoted with the increase of operating temperature,while the increase of SO32- concentration would inhibit Hg2＋reduction by forming the complex Hg（SO3）22-.Lower pH value enhanced the re-emission of Hg0 for the reason that complex HgSO3 was apt to decompose due to its protonation.The presence of O2would break the stabilization of Hg（SO3）22- resulting in Hg2＋ re-emission.In the meanwhile,more SO42- contributed by higher pH value,which would help the inhibition of Hg2＋ emission.