Characteristics and Kinetics Study of Mercury Re-emission Inhibited by DTCR in Simulated Desulfurization Slurry

The mercury re-emission characteristics and inhibition effect of sodium dithiocarbamate (DTCR) on mercury re-emission in a simulated desulfurization slurry were investigated. The effects of the desulfurization slurry parameters (including slurry temperature, initial pH value, O-2 concentration, and Cl- concentration) on mercury re-emission with and without DTCR were explored. Moreover, the kinetic parameters (reaction order, reaction rate constant, and apparent activation energy) of mercury re-emission and inhibition were calculated by the experimental data. The results showed that addition of DTCR could effectively reduce the mercury re-emission from the desulfurization slurry. The mercury re-emission was enhanced with increases of the slurry temperature and initial pH, while O-2 and Cl- in the slurry could inhibit the mercury re-emission. Further study shows that the mercury re-emission reaction processes in the desulfurization slurry with and without DTCR are both consistent with the pseudo-first-order kinetics. In the absence of DTCR, the reaction rate constant of mercury re-emission is 0.01888 min(-1), and the apparent activation energy is 44.59 kJ/mol. In the presence of 0.002% DTCR, the reaction rate constant of mercury re-emission is 0.01126 min(-1) and the apparent activation energy is 49.08 kJ/mol. Moreover, the effects of slurry parameters on the reaction rate constant were also explored. The present findings are valuable for coal-fired power plants to control mercury re-emission from a desulfurization slurry.