Mechanism of Hg2+ reduction in wet flue gas desulfurization liquors
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摘要: 针对燃煤电厂湿法脱硫浆液中Hg2+易被还原的特性，研究Hg2+在模拟湿法脱硫系统中的迁移机制，考察了浆液温度、pH值以及SO32-、Cl-、Ca2+、Mg2+浓度等因素对Hg2+还原性能的影响。结果表明，Hg2+还原率随着浆液中SO32-浓度的增大而降低；pH值对Hg2+的还原呈先增加后降低的趋势，在pH值为5.5时还原率最高；温度的升高不利于浆液中稳定的二价汞盐络合物存在，导致Hg2+还原率增加；Ca2+、Mg2+以及Cl-浓度的增加有利于形成稳定化合物，从而抑制Hg2+的还原。Abstract: 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 SO32-, Cl-, Ca2+ and Mg2+ were investigated separately. The results indicate that the increase of SO32- 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+.
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Key words:
- Hg2+ reduction /
- pH value /
- slurry temperature /
- ion concentration /
- wet desulfurization
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图 2 SO32-浓度对Hg2+还原性能的影响
Figure 2 Effects of different SO32- concentrations on Hg2+ reduction
experimental conditions: reaction temperature 55℃, pH value = 5.5, 1.5L/min N2 as balance gas■: SO32-=10mmol/L; ● : SO32-=5mmol/L; ▲: SO32-=1mmol/L
图 3 pH值对Hg2+还原性能的影响
Figure 3 Effects of different pH values on Hg2+ reduction
experimental conditions: reaction temperature 55℃, 5mmol/L SO32-, 1.5L/min N2 as balance gas ■: pH=5.5; ●: pH=4; ▲: pH=3; ▼: pH=7
图 4 浆液温度对Hg2+还原性能的影响
Figure 4 Effects of different slurry temperature on Hg2+ reduction
experimental conditions: pH value = 5.5, 5mmol/L SO32-, 1.5L/min N2 as balance gas ■: 40℃; ●: 55℃; ▲: 70℃
图 5 Cl-浓度对Hg2+还原性能的影响
Figure 5 Effects of different Cl- concentrations on Hg2+ reduction
experimental conditions: reaction temperature 55℃, pH value = 5.5, 5mmol/L SO32-, 1.5L/min N2 as balance gas ■: Cl-=200mmol/L; ● : Cl-=100mmol/L; ▲: Cl-=1mmol/L
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