LAUSR

Abstract In this paper, the mercury re-emission from desulfurization slurry and mercury distribution in gas-liquid-solid three-phase at different desulfurization slurry parameters were studied. Besides, the inhibition performance of Fenton reagent for mercury re-emission and distribution was also investigated. The results show that the Hg0 would re-emit from desulfurization slurry, and the proportions of mercury in gas-liquid-solid three-phase were about 12.17%, 77.72% and 12.08% at typical desulfurization slurry parameter. The S(IV) concentration (sulfite and/or bisulfite concentration), temperature and pH value of desulfurization slurry had great impacts on mercury re-emission and distribution. The increase of S(IV) concentration weakened the mercury re-emission, increased the proportions of mercury in solid phase and liquid phase. The increase of slurry temperature could intensify the mercury re-emission, increase the proportion of mercury in solid phase, but decrease the proportion of mercury in liquid phase. Higher pH value was favorable for the weakening of mercury re-emission, but would increase the proportion of mercury in solid phase and liquid phase. Moreover, the introduction of Fenton reagent into desulfurization slurry could inhibit the mercury re-emission and some mercury that should be re-emitted before would be restrained in solid phase, leading a slight increase of proportion of mercury in solid phase. The existing of oxygenated free radicals, which were generated from Fenton reagent, was the main reason for the inhibition of mercury re-emission. The increase of Fe2+ and H2O2 concentration was conducive to the promotion of inhibition performance, but the effect gradually to weaken. The appropriate value of Fe2+ concentration was 0.04 mM with the H2O2 concentration of 0.30 mM in experiments. In addition, the better inhibition performance (about 80%) of Fenton reagent for mercury re-emission would be realized at lower S(IV) concentration (1–5 mM), lower temperature (30–40 °C) and lower pH value (4.0–5.0) of slurry.