烟气单质汞氧化去除过程络合反应机理
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摘要
湿法氧化去除烟气Hg~0过程中产物Hg~(2+)易发生络合反应,络合产物可能改变氧化体系形成新反应机制,这一现象尚未被认识研究.为获得Hg~(2+)络合物生成及其对烟气脱汞影响机理,研究了配体阳离子、配体浓度、反应p H值、反应温度和摩尔比等对Hg~(2+)络合反应的影响和氧化去除烟气Hg~0的络合反应机理.结果表明MgCl_2、KCl、NiCl_2和BaCl_2配体均能与HgCl_2形成络合物,而CuCl_2和SnCl_4则不能生成络合物.络合物生成量随配体浓度的增加先升高然后趋于平衡;络合反应在酸性环境下发生且不受p H值变化影响;碱性环境下络合反应不能进行;反应温度基本不影响络合反应效应;增加配体浓度可提高络合物产量,不同配体络合效应不同,但最大吸光度基本相同,为(4.20±0.03)A.配体对络合反应有响应区间,低于区间下限值时不能形成络合物,高于上限制值时络合物产量不随配体浓度而变化.HgCl_2络合反应累积稳定常数β_4=10~(15.07);[HgCl_4]~(2-)可螯合Hg(aq)和O_2(aq)使其与Cl O~-和Hg_2Cl_2反应,形成氧化-络合氧化反应新机理.
The product Hg~(2+)was prone to complexation during the process of wet oxidation to remove Hg~0 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 p H,reaction temperature and molar ratio on the complexation reaction of Hg~(2+)and the complexation mechanism in the oxidation removal of Hg~0 in flue gas were studied.The results showed that MgCl_2,KCl,NiCl_2 and BaCl_2 could be complexed with HgCl_2 but neither CuCl_2 or SnCl_4.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 p H 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 constantβ_4 was 10~(15.07).The complex[HgCl_4]~(2-)had the ability to chelate Hg(aq)and O_2(aq),then react with ClO~- and Hg_2Cl_2.A new oxidation-complexation oxidation reaction mechanism was formed.
The product Hg~(2+)was prone to complexation during the process of wet oxidation to remove Hg~0 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 p H,reaction temperature and molar ratio on the complexation reaction of Hg~(2+)and the complexation mechanism in the oxidation removal of Hg~0 in flue gas were studied.The results showed that MgCl_2,KCl,NiCl_2 and BaCl_2 could be complexed with HgCl_2 but neither CuCl_2 or SnCl_4.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 p H 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 constantβ_4 was 10~(15.07).The complex[HgCl_4]~(2-)had the ability to chelate Hg(aq)and O_2(aq),then react with ClO~- and Hg_2Cl_2.A new oxidation-complexation oxidation reaction mechanism was formed.
引文
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[7] Gao X C, Ma X X, Kang X, et al. Oxidative Absorption of NO by Sodium Persulfate Coupled with Fe2+, Fe3O4, and H2O2[J].Environmental Progress and Sustainable Energy, 2015,34(1):117-124.
[8] Liu Y, Wang Y, Wang Q, et al. A study on removal of elemental mercury in flue gas using fenton solution[J]. Journal of Hazardous Materials, 2015,292:164-172.
[9] Zhou C, Sun L, Zhang A, et al.Fe3-x Cux O4 as highly active heterogeneous Fenton-like catalysts toward elemental mercury removal[J]. Chemosphere, 2015,125:16-24.
[10] Liu Y, Zhou J, Zhang Y, et al. Removal of Hg0 and simultaneous removal of Hg0/SO2/NO in flue gas using two Fenton-like reagents in a spray reactor[J]. Fuel, 2015,145:180-188.
[11] Yi Z, Yao J, Ma X. Absorption Behavior and Removal of Gaseous Elemental Mercury by Sodium Chlorite Solutions[J]. Journal of Environmental Engineering, 2012,138(6):620-624.
[12] Zhao Y, Guo T, Chen Z, et al. Simultaneous removal of SO2 and NO using M/NaClO2 complex absorbent[J].Chemical Engineering Journal,2010,160(1):42-47.
[13]乔少华,晏乃强,陈杰,等.MnOχ/α-Al2O3催化氧化燃煤烟气中Hg0的试验研究[J].中国环境科学, 2009,29(3):237-241.Qiao S H, Yan N Q, Chen J, et al. Catalytic oxidation of elemental mercury in flue gas on MnOx/α-Al2O3[J]. China Environmental Science, 2009,29(3):237-241.
[14]王运军,段钰锋,杨立国,等.湿法、半干法和循环流化床炉内脱硫技术的脱汞特性[J].燃烧科学与技术, 2009,4(15):368-373.Wang Y J, Duan Y F, Yang L G, et al. Mercury Removal by Wet,Semi-Dry and Furnace Desulphurization Technology in Circulating Fluidized Bed[J]. Journal of Combustion Science and Technology,2009,4(15):368-373.
[15]邢微波,路好,张安超,等. Ag/AgCl可见光催化剂湿法脱除烟气中单质汞[J].中国环境科学, 2017,37(2):503-510.Xing W B, Lu H, Zhang A C, et al. Wet process of elemental mercury removal from flue gas using Ag/AgCl photocatalyst under visible light[J]. China Environmental Science, 2017,37(2):503-510.
[16]李兵,王宏亮,许月阳,等.燃煤电厂湿法脱硫设施对烟气中微量元素的减排特性[J].煤炭学报, 2015,10(40):2479-2483.Li B, Wang H L, Xu YY, et al.Reduction of trace elements in flue gas by wet desulphurization facilities in coal-fired power plants[J].Journal of China Coal Society, 2015,40(10):2479-2483.
[17]郑逸武,段钰锋,汤红健,等.燃煤烟气污染物控制装置协同脱汞特性研究[J].中国环境科学, 2018,38(3):862-870.Zheng Y W, Duan Y F, Tang H J, et al. Characteristics of the existing air pollutant control devices on Hg synergistic removal in a coal-fired power plant[J]. China Environmental Science, 2018,38(3):862-870.
[18]刘盛余,能子礼超,刘沛,等.高锰酸钾氧化吸收烟气中单质汞的研究[J].环境工程学报, 2011,5(7):1612-1617.Liu S Y, Nengzi L C, Liu P, et al. Oxidation absorption of mercury from flue gas by KMnO4[J]. Chinese Journal of Environmental Engineering, 2011,5(7):1612-1617.
[19] Pavlish J H, Sondreal E A, Mann M D, et al. Status review of mercury control options for coal-fired power plants[J]. Fuel Processing Technology, 2003,82(2/3):89-165.
[20]阮长超,胡辉,黄浩,等.氯酸盐系列湿式氧化Hg0的影响因子实验研究[J].环境工程, 2017,37(11):76-81.Ruan C C, Hu H, Huang H, et al. Research on the impact factors in wet oxidation of Hg0 by chlorate series[J]. Environmental Engineering, 2017,37(11):76-81.
[21]大连理工大学无机化学教研室,无机化学[M].北京:高等教育出版社, 2006:618-630.Department of Inorganic Chemistry, Dalian University of Technology,Inorganic Chemistry[M]. Beijing:Higher Education Press, 2006:618-630.
[22]孙为银,配位化学[M].化学工业出版社, 2005:236-240.Sun W Y, Coordination Chemistry[M]. Chemical Industry Press,2005:236-240.
[23]张昭文,靖汪建,申利芬.氯离子浓度对湿法烟气脱硫工艺的影响[J].工业安全与环保, 2009,11(35):28-29.Zhang Z W, Jing W J, Shen L F. Effect of Chloride Ion Concentration on wet Limestone Gypsum Deslurfrization Technology[J]. Industrial Safety and Environmental Protection, 2009,11(35):28-29.
[24]殷立宝,余亮英,徐齐胜,等.氯、氟离子对烟气中汞形态和分布的影响[J].热力发电, 2014,10(43):16-19.Yin L B, Yu L Y, Xu Q S, et al. Effect of Chlorine and Fluorine Elements on Mercury Species and its Distribution in Flue Gas[J].Thermal Power Generation, 2014,10(43):16-19.
[25] Sheng-Yu Liu, Li-chao Nengzi, Bin Qu, et al. Simultaneous removal of elemental mercury in aqueous by oxidation[J]. Environment Engineering Science, 2010,27(4):323-327.
[26]王丽萍,许锐伟,田立江,等.过硫酸钾对WFGD系统中气态汞的氧化去除性能的影响[J].中国矿业大学学报, 2016,4(45):794-798.Wang L P, Xu R W, Tian L J, et al. Effect of K2S2O8 on oxidation and removal of gaseous mercury in wet flue gas desulfurization[J]. Journal of China University of Mining and Technology, 2016,4(45):794-798.
[27]赵毅,齐萌.氧化法去除燃煤烟气中Hg0技术的研究进展[J].化工环保, 2018,3(38):256-260.Zhao Y, Qi M. Review on removal of elemental mercury from coal combustion flue gas by oxidation progress[J]. Environmental Protection of Chemical Industry, 2018,3(38):256-260.
[28]付康丽,赵婷雯,姚明宇,等.燃煤烟气脱汞技术研究进展[J].热力发电, 2017,46(6):1-5.Fu K L, Zhao T W, Yao M Y, et al.Mercury removal technology for coal-fired flue gas:research progress[J]. Thermal Power Generation,2017,46(6):1-5.
[2]刘盛余,能子礼超,赖亮,等.燃煤烟气中单质汞的氧化吸收研究[J].煤炭学报, 2010,35(2):303-306.Liu S Y, Nengzi L C, Lai L, et al. Removal of elemental mercury by oxidation from flue gas[J]. Journal of China Coal Society, 2010,35(2):303-306.
[3] Yao H, Luo G, Xu M, et al. Mercury emission and species during combustion of coal and waste[J]. Energy&Fuels, 2006,20(5):1946-1950.
[4] Zhou Z J, Liu X W, Zhao B, et al. Effects of existing energy saving and air pollution control devices on mercury removal in coalfired power plants[J]. Fuel Processing Technology, 2015,131:99-108.
[5] Fang P, Cen C, Wang X, et al. Simultaneous removal of SO2, NO and Hg0 by wet scrubbing using urea+KMnO4 solution[J]. Fuel Processing Technology, 2013,106:645-653.
[6]孙冠,杨晓秋,史惠祥,等.过硫酸钾脱除气态元素汞的试验研究[J].环境污染与防治, 2007,29(3):168-170.Sun G, Yang X Q, Shi H X, et al. Removal of gaseous elemental mercury in potassium persulfate solution[J]. Environmental Pollution&Control, 2007,29(3):168-170.
[7] Gao X C, Ma X X, Kang X, et al. Oxidative Absorption of NO by Sodium Persulfate Coupled with Fe2+, Fe3O4, and H2O2[J].Environmental Progress and Sustainable Energy, 2015,34(1):117-124.
[8] Liu Y, Wang Y, Wang Q, et al. A study on removal of elemental mercury in flue gas using fenton solution[J]. Journal of Hazardous Materials, 2015,292:164-172.
[9] Zhou C, Sun L, Zhang A, et al.Fe3-x Cux O4 as highly active heterogeneous Fenton-like catalysts toward elemental mercury removal[J]. Chemosphere, 2015,125:16-24.
[10] Liu Y, Zhou J, Zhang Y, et al. Removal of Hg0 and simultaneous removal of Hg0/SO2/NO in flue gas using two Fenton-like reagents in a spray reactor[J]. Fuel, 2015,145:180-188.
[11] Yi Z, Yao J, Ma X. Absorption Behavior and Removal of Gaseous Elemental Mercury by Sodium Chlorite Solutions[J]. Journal of Environmental Engineering, 2012,138(6):620-624.
[12] Zhao Y, Guo T, Chen Z, et al. Simultaneous removal of SO2 and NO using M/NaClO2 complex absorbent[J].Chemical Engineering Journal,2010,160(1):42-47.
[13]乔少华,晏乃强,陈杰,等.MnOχ/α-Al2O3催化氧化燃煤烟气中Hg0的试验研究[J].中国环境科学, 2009,29(3):237-241.Qiao S H, Yan N Q, Chen J, et al. Catalytic oxidation of elemental mercury in flue gas on MnOx/α-Al2O3[J]. China Environmental Science, 2009,29(3):237-241.
[14]王运军,段钰锋,杨立国,等.湿法、半干法和循环流化床炉内脱硫技术的脱汞特性[J].燃烧科学与技术, 2009,4(15):368-373.Wang Y J, Duan Y F, Yang L G, et al. Mercury Removal by Wet,Semi-Dry and Furnace Desulphurization Technology in Circulating Fluidized Bed[J]. Journal of Combustion Science and Technology,2009,4(15):368-373.
[15]邢微波,路好,张安超,等. Ag/AgCl可见光催化剂湿法脱除烟气中单质汞[J].中国环境科学, 2017,37(2):503-510.Xing W B, Lu H, Zhang A C, et al. Wet process of elemental mercury removal from flue gas using Ag/AgCl photocatalyst under visible light[J]. China Environmental Science, 2017,37(2):503-510.
[16]李兵,王宏亮,许月阳,等.燃煤电厂湿法脱硫设施对烟气中微量元素的减排特性[J].煤炭学报, 2015,10(40):2479-2483.Li B, Wang H L, Xu YY, et al.Reduction of trace elements in flue gas by wet desulphurization facilities in coal-fired power plants[J].Journal of China Coal Society, 2015,40(10):2479-2483.
[17]郑逸武,段钰锋,汤红健,等.燃煤烟气污染物控制装置协同脱汞特性研究[J].中国环境科学, 2018,38(3):862-870.Zheng Y W, Duan Y F, Tang H J, et al. Characteristics of the existing air pollutant control devices on Hg synergistic removal in a coal-fired power plant[J]. China Environmental Science, 2018,38(3):862-870.
[18]刘盛余,能子礼超,刘沛,等.高锰酸钾氧化吸收烟气中单质汞的研究[J].环境工程学报, 2011,5(7):1612-1617.Liu S Y, Nengzi L C, Liu P, et al. Oxidation absorption of mercury from flue gas by KMnO4[J]. Chinese Journal of Environmental Engineering, 2011,5(7):1612-1617.
[19] Pavlish J H, Sondreal E A, Mann M D, et al. Status review of mercury control options for coal-fired power plants[J]. Fuel Processing Technology, 2003,82(2/3):89-165.
[20]阮长超,胡辉,黄浩,等.氯酸盐系列湿式氧化Hg0的影响因子实验研究[J].环境工程, 2017,37(11):76-81.Ruan C C, Hu H, Huang H, et al. Research on the impact factors in wet oxidation of Hg0 by chlorate series[J]. Environmental Engineering, 2017,37(11):76-81.
[21]大连理工大学无机化学教研室,无机化学[M].北京:高等教育出版社, 2006:618-630.Department of Inorganic Chemistry, Dalian University of Technology,Inorganic Chemistry[M]. Beijing:Higher Education Press, 2006:618-630.
[22]孙为银,配位化学[M].化学工业出版社, 2005:236-240.Sun W Y, Coordination Chemistry[M]. Chemical Industry Press,2005:236-240.
[23]张昭文,靖汪建,申利芬.氯离子浓度对湿法烟气脱硫工艺的影响[J].工业安全与环保, 2009,11(35):28-29.Zhang Z W, Jing W J, Shen L F. Effect of Chloride Ion Concentration on wet Limestone Gypsum Deslurfrization Technology[J]. Industrial Safety and Environmental Protection, 2009,11(35):28-29.
[24]殷立宝,余亮英,徐齐胜,等.氯、氟离子对烟气中汞形态和分布的影响[J].热力发电, 2014,10(43):16-19.Yin L B, Yu L Y, Xu Q S, et al. Effect of Chlorine and Fluorine Elements on Mercury Species and its Distribution in Flue Gas[J].Thermal Power Generation, 2014,10(43):16-19.
[25] Sheng-Yu Liu, Li-chao Nengzi, Bin Qu, et al. Simultaneous removal of elemental mercury in aqueous by oxidation[J]. Environment Engineering Science, 2010,27(4):323-327.
[26]王丽萍,许锐伟,田立江,等.过硫酸钾对WFGD系统中气态汞的氧化去除性能的影响[J].中国矿业大学学报, 2016,4(45):794-798.Wang L P, Xu R W, Tian L J, et al. Effect of K2S2O8 on oxidation and removal of gaseous mercury in wet flue gas desulfurization[J]. Journal of China University of Mining and Technology, 2016,4(45):794-798.
[27]赵毅,齐萌.氧化法去除燃煤烟气中Hg0技术的研究进展[J].化工环保, 2018,3(38):256-260.Zhao Y, Qi M. Review on removal of elemental mercury from coal combustion flue gas by oxidation progress[J]. Environmental Protection of Chemical Industry, 2018,3(38):256-260.
[28]付康丽,赵婷雯,姚明宇,等.燃煤烟气脱汞技术研究进展[J].热力发电, 2017,46(6):1-5.Fu K L, Zhao T W, Yao M Y, et al.Mercury removal technology for coal-fired flue gas:research progress[J]. Thermal Power Generation,2017,46(6):1-5.
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