Hg2+ reduction and re-emission from simulated wet flue gas desulfurization liquors.
In this study, considering that Hg(2+) in wet flue gas desulfurization (FGD) systems can easily be reduced and then released into atmosphere, causing secondary pollution, the researches about Hg(2+) reduction and Hg(0) re-emission mechanism were carried out. The effects of several experimental parameters on the reduction were studied, including initial pH, temperature, and concentrations of Cl(-) and S(IV). Our experimental results indicated that Cl(-) had a restraining effect on the Hg(2+) reduction and Hg(0) re-emission, after 24h reaction, only 20.5% of Hg(2+) was reduced with 100mM Cl(-) in simulated desulfurization solution. Cl(-) can slow Hg(2+) reduction and Hg(0) re-emissions dramatically through changing reaction mechanism, with formation of new intermediate: ClHgSO(3)(-), which can decompose to Hg(0), but much more slowly than Hg(SO(3))(2)(2-) or HgSO(3). Simulating the conditions of the practical application (initial pH 5, T=50 degrees C, S(IV)=5 mM, Cl(-)=100 mM), we also found that Ca(2+), NO(3)(-), F(-), etc. all had obvious effects on reduction rates. Based on the material balance and characteristic of the reactants, the reduction emission mechanism of Hg(2+) has been established, providing theoretical basis for industrial application of mercury control in wet FGD systems.
Wo
Jingjing
J
Department of Environmental Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China.
Zhang
Meng
M
Cheng
Xiaoya
X
Zhong
Xiaohang
X
Xu
Jiang
J
Xu
Xinhua
X
D000393:Air Pollutants / Q000737:chemistry; D000397:Air Pollution; D002712:Chlorides / Q000737:chemistry; D005740:Gases; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D008628:Mercury / Q000737:chemistry*; D010084:Oxidation-Reduction; D019163:Reducing Agents; D013455:Sulfur / Q000737:chemistry; D013696:Temperature
D000393:Air Pollutants; D002712:Chlorides; D005740:Gases; D007220:Industrial Waste; D019163:Reducing Agents; D013455:Sulfur; D008628:Mercury