Study on the mechanism of complexation reaction in the process of mercury removal from flue gas
NENGZI Li-chao1,3, SUN Jin1, YANG Hong1,3, WANG Xue-mei1, HU Jin-zhao1, LIU Sheng-yu2, GUO Fei3
1. College of Resources and Environment, Xichang University, Xichang 615000, China;
2. College of Resources and Environment, Chengdu University of Information Technology, Chengdu 610225, China;
3. Academy of Environmental and Economics Sciences, Xichang University, Xichang 615000, China
The product Hg2+ was prone to complexation during the process of wet oxidation to remove Hg0 from flue gas. The complexation product may change the oxidation mechanism to form a new reaction mechanism. This phenomenon has not been studied. The effects of ligand cation, ligand concentration, reaction pH, reaction temperature and molar ratio on the complexation reaction of Hg2+ and the complexation mechanism in the oxidation removal of Hg0 in flue gas were studied. The results showed that MgCl2, KCl, NiCl2 and BaCl2 could be complexed with HgCl2 but neither CuCl2 or SnCl4. The amount of complex formation increased first with ligand concentration increasing and then tended to be equilibrium. The acidic reaction environment was beneficial to the complexation reaction and not affected by the pH change. However, the complexation reaction could not occur in the alkaline reaction environment. The reaction temperature did not affect the complexation reaction. The absorbance of all the complexes produced was basically the same, this value was (4.20 ±0.03) A. The mercury complexation reaction had a response interval to the ligand concentration. When the ligand concentration was less than the lower limit of the interval, complex could not be formed. When the ligand concentration was more than the upper limit of the interval, the complex yield did not change with the ligand concentration. When the mercury atom sp orbit was recombined, it was difficult for the 6d empty orbit to participate in the hybridization to form a high-spin outer rail type complex. The cumulative stability constant β4 was 1015.07. The complex[HgCl4]2- had the ability to chelate Hg (aq) and O2 (aq), then react with ClO- and Hg2Cl2. A new oxidation-complexation oxidation reaction mechanism was formed.
能子礼超, 孙劲, 杨红, 王雪梅, 胡金朝, 刘盛余, 郭飞. 烟气单质汞氧化去除过程络合反应机理[J]. 中国环境科学, 2019, 39(9): 3727-3735.
NENGZI Li-chao, SUN Jin, YANG Hong, WANG Xue-mei, HU Jin-zhao, LIU Sheng-yu, GUO Fei. Study on the mechanism of complexation reaction in the process of mercury removal from flue gas. CHINA ENVIRONMENTAL SCIENCECE, 2019, 39(9): 3727-3735.
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