抑制双碱法烟气脱硫浆液中SO_3^(2-)的重金属催化氧化  

Inhibition of Sulfite Oxidation Catalyzed by Heavy Metals in Dual Alkali Flue Gas Desulfurization Slurry

作　　者：于洁[1] 官宝红[1] 刘文霞[1] 胡达清[1] 吴忠标[1] 

机构地区：[1]浙江大学环境工程系,杭州310027

出　　处：《环境科学》2010年第3期591-597,共7页Environmental Science

基　　金：国家高技术研究发展计划(863)项目(2006AA06Z385);教育部优秀人才支持计划项目(NCET-04-0549)

摘　　要：双碱法烟气脱硫浆液中累积的重金属对SO23-有强烈的催化氧化作用,导致有效脱硫组分损耗.投加Na2S去除浆液中的重金属离子,研究不同重金属离子浓度下SO23-的氧化速率,以揭示Na2S沉淀法对重金属催化氧化SO32-的抑制作用.实验表明,Mn2+对SO32-氧化的催化作用很显著,1.0 mmol/L Mn2+可使SO32-的初始氧化速率提高2.0倍,达0.65mmol/(L.min);SO23-的催化氧化在前60 min内快速进行,Mn2+的反应级数为0.169,故此时段内控制Mn2+浓度对抑制其催化作用尤为重要.初始pH6.50~8.50时,Na2S能有效去除浆液中重金属离子,且碱性条件更有利于重金属离子的去除.初始pH为8.50、Na2S投加量为240.0 mg/L时,脱硫浆液中Mn2+、Zn2+、Ni2+、Cd2+的去除率分别为91.0%、88.1%、85.5%和>99.9%.Mn2+对脱硫浆液中的重金属离子浓度具有指示作用.投加Na2S将Mn2+浓度由1.0 mmol/L降为5.0×10-3mmol/L,SO32-的初始氧化速率降低64.6%,为0.23 mmol/(L.min).在双碱法烟气脱硫中试装置中投加Na2S可使脱硫效率提高3.8%~5.1%.故以Mn2+为指示、用Na2S控制重金属离子浓度从而抑制SO23-被催化氧化,有利于降低脱硫剂消耗、提高脱硫效率.Heavy metals accumulated in slurry of dual alkali flue gas desulfurization（FGD） present a significant catalysis to SO2^-3 oxidation,resulting in a waste of effective components for desulfurization.Na2S was adopted to precipitate heavy metal ions in FGD slurry,and the oxidation rate of SO2^-3 was obtained under different concentrations of heavy metal ions,to reveal the inhibition effect of Na2S on SO2^-3 oxidation catalyzed by heavy metal ions.Mn^2＋ showed a remarkable catalysis to SO2^-3 oxidation,as the initial oxidation rate of SO2^-3 was tripled to 0.65 mmol/（L·min） by adding 1.0 mmol/L Mn^2＋ into the slurry.SO2^-3 was catalytically oxidized rapidly with the reaction order 0.169 of Mn2＋ within first 60 minutes,so it is of great importance to control the concentration of Mn^2＋ to inhibit SO2^-3 oxidation.At initial pH value of 6.50-8.50,Na2S removed heavy metal ions effectively from FGD slurry.Higher pH value favored the removal of heavy metal ions.The removal efficiencies of Mn^2＋,Zn^2＋, Ni^2＋ and Cd^2＋ were 91.0%,88.1%,85.5%,and above 99.9% respectively under the conditions of initial pH value 8.50 and Na2S dosage 240.0 mg/L.Mn^2＋ could be used as an indicator for the concentration of the heavy metal ions in the slurry.As the Mn^2＋ concentration decreased from 1.0 mmol/L to 5.0×10^-3 mmol/L by adding Na2S,the initial oxidation rate of SO2^-3 decreased by 64.6% to 0.23 mmol/（L·min）.The desulfurization efficiencies increase 3.8%-5.1% by adding Na2S in a pilot scale setup.It comes to conclusion that heavy metal ions precipitation by adding Na2S with an indicator of Mn^2＋ to inhibit catalytic oxidation of SO2^-3 is feasible to reduce the consumption of desulfurizer in FGD slurry.

关 键 词：双碱法 烟气脱硫 亚硫酸根 重金属 催化氧化 抑制 

分 类 号：X701.3[环境科学与工程—环境工程]