添加剂对抑制模拟脱硫浆液中汞再释放的影响

针对湿法脱硫系统中汞还原再释放问题,选用Na_2S、2,4,6-三硫醇基钠代三嗪(TMT-18)、二硫代氨基甲酸盐类(DTCR-2)和Fenton试剂作为添加剂,探究其对脱硫浆液中汞再释放现象的影响。结果表明,四种添加剂均能有效抑制该现象的发生。1.0倍化学计量比的Na_2S足够与浆液中Hg~(2+)结合成HgS,从而将还原再释放的汞含量降低至5.27%。重金属捕集剂TMT-18和DTCR-2的最佳投加量分别为3.0倍和1.0倍化学计量比,通过与Hg~(2+)结合形成有机螯合物将浆液中的汞固定在螯合产物中,从而降低Hg~(2+)的还原,再释放的汞含量分别降低至5.09%和4.62%。具有强氧化性的Fenton试剂,当H_2O_2浓度为0.3 mol/L,[Fe~(2+)]/[H_2O_2]=1∶8时,浆液中仅有2.31%的汞被还原再释放。四种添加剂中Fenton对于浆液中汞还原再释放的抑制效果最好。

Effects of additives on stabilization and inhibition of mercury re-emission in simulated wet gas desulphurization slurry

In view of the problem of mercury re-emission in wet flue gas desulfurization system, Na₂S, 2,4,6-trimercaptotiazine trisodium (TMT-18), sodium dithiocarbamate (DTCR-2) and Fenton reagents were added into the desulfurization slurry to study their effects on mercury re-emission. The results show that the 4 additives could effectively inhibit the mercury re-emission. 1.0 time stoichiometric ratio of Na₂S is enough to combine with Hg²⁺ in the slurry into HgS. Thereby the ratio of mercury re-emission reduces to 5.27%. The optimum dosage of heavy metal chelating agents TMT-18 and DTCR-2 are 3.0 and 1.0 time stoichiometric ratio. They combine with Hg²⁺ to form organic chelate mercury and then fix it. So the ratio of mercury re-emission reduces to 5.09% and 4.62%, respectively. After adding Fenton reagent with a strong oxidizing into the slurry, the ratio of reduced mercury reduces to only 2.31% when H₂O₂ concentration is 0.3 mol/L and the ratio of[Fe²⁺]/[H₂O₂] is 1:8. Fenton reagent has the best effect on mercury re-emission in the simulated wet gas desulphurization slurry among 4 additives.