Mechanism of Hg²⁺ reduction in wet flue gas desulfurization liquors

Given the easy reduction of Hg²⁺ in wet desulfurization slurry in a power plant, migration mechanism of Hg²⁺ in a simulated system was studied. Influences of several experimental parameters including slurry temperature, pH value and concentrations of SO₃^2-, Cl^-, Ca²⁺ and Mg²⁺ were investigated separately. The results indicate that the increase of SO₃^2- concentration lowers the reduction rate of Hg²⁺, while the rise of slurry temperature leads to an opposite result. The effect of pH value shows a trend of first increase and then decrease, and reaches the highest reduction rate at pH value of 5.5. Moreover, the rise of Ca²⁺, Mg²⁺ and Cl^- concentrations could inhibit the reduction of Hg²⁺.