液相射频放电等离子体降解水中三氯甲烷和腐殖酸的研究
发布时间：2018-10-14 18:30
【摘要】：三氯甲烷(CHCl3)属于常见的卤代有机污染物,广泛应用于工业生产生活中,也可由氯法消毒产生,长期接触对人体健康有严重危害。腐殖酸(HA)广泛存在于天然水体中,是氯法消毒生成三氯甲烷反应的前驱物质,同时也可增加患大骨节病的概率、引起水体浑浊等环境问题。近年来,液相射频等离子体因为具有击穿电压低,可在常压发生,能量效率高等特点而逐渐得到了越来越多的关注。本研究自行设计了液相射频等离子体发生装置,研究了其对三氯甲烷和腐殖酸的降解效果,主要结论如下:(1)通过发射光谱检测到液相射频等离子体中主要产生的自由基为.OH和·H,电导率范围在0.10～0.80mS/cm时,·OH的发射强度随着电导率的增大而增强;电导率范围在0.80～6.00mS/cm时,.OH的发射强度随着电导率的增大而减弱;(2)提高溶液初始pH、添加自由基清除剂、NO3-可以提高CHCl3的去除率,HCO3-可以起到缓冲作用和消耗·OH间接提高·H浓度的作用,产物无污染,是提高CHC13去除率的理想物质;主要降解中间产物为HCOOH、H2C2O4和CH2Cl2,·H和eaq-是引发CHCl3脱氯的关键物质,并对有机酸和二氯甲基自由基的产生和转化起到重要作用,·OH则主要对有机酸的降解做出贡献,最终产物为CO2、H2O和HCl,放电过程中的局部高温对CHCl3的富集和热解也有助于其去除;液相射频等离子体技术也可对CH2Cl2进行有效去除,机理与CHCl3类似;(3)加入Fe2+与溶液中产生的H202形成Fenton反应协同处理HA取得了很好的效果,最佳pH范围为3.50～5.50,当HA初始浓度30mg/L时,最佳Fe2+投加浓度为20mg/L,去除率可达90.23%;对于高浓度的HA溶液也有良好的去除效果,Fe2+初始浓度20mg/L,HA初始浓度60mg/L时,HA去除率可达95.33%;经放电处理后HA的芳香度减弱,大分子被分解为小分子,C=C、C-O、羟基强度下降,而-CH-的强度有所增加。
[Abstract]:Trichloromethane (CHCl3), a common halogenated organic pollutant, is widely used in industrial production and can also be produced by chlorine disinfection. Humic acid (HA) is a precursor of chlorination to form trichloromethane in natural water, and it can also increase the probability of Kaschin-Beck disease and cause environmental problems such as turbidity of water body. In recent years, more and more attention has been paid to liquid radio frequency plasma because of its low breakdown voltage, high energy efficiency and low breakdown voltage. In this study, a liquid phase RF plasma generator was designed to study the degradation of trichloromethane and humic acid. The main conclusions are as follows: (1) the main free radicals produced in liquid radio frequency plasma are. OH and H by emission spectrum. When the conductivity range is 0.10~0.80mS/cm, the emission intensity of OH increases with the increase of conductivity. When the conductivity is in the range of 0.80~6.00mS/cm, the emission intensity of,. OH decreases with the increase of conductivity. (2) when the solution initial pH, is added with free radical scavenger, NO3- can increase the removal rate of CHCl3, HCO3- can play a buffer role and consume OH to increase H concentration indirectly. The main degradation intermediates are HCOOH,H2C2O4, CH2Cl2, H and eaq-, which are the key substances to initiate the dechlorination of CHCl3. It also plays an important role in the production and transformation of organic acids and dichloromethyl radicals, while OH mainly contributes to the degradation of organic acids. The final product is the partial high temperature during the discharge of CO2,H2O and HCl, and the enrichment and pyrolysis of CHCl3 are also helpful to its removal. The liquid-phase RF plasma technology can also effectively remove CH2Cl2, and the mechanism is similar to that of CHCl3. (3) the synergistic treatment of HA with H202 produced in solution by adding Fe2 has a good effect. The optimum pH range is 3.50 ~ 5.50, and when the initial concentration of HA is 30mg/L, The optimal concentration of Fe2 was 20mg / L, and the removal rate was 90.23.The removal rate of HA was 95.33 when the initial concentration of Fe2 was 20mg / L, 60mg/L, and the aromaticity of HA decreased after the discharge treatment. When the macromolecules are decomposed into small molecules, the strength of the hydroxyl group decreases, while the strength of-CH- increases.
【学位授予单位】：大连海事大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703
本文编号：2271272
[Abstract]:Trichloromethane (CHCl3), a common halogenated organic pollutant, is widely used in industrial production and can also be produced by chlorine disinfection. Humic acid (HA) is a precursor of chlorination to form trichloromethane in natural water, and it can also increase the probability of Kaschin-Beck disease and cause environmental problems such as turbidity of water body. In recent years, more and more attention has been paid to liquid radio frequency plasma because of its low breakdown voltage, high energy efficiency and low breakdown voltage. In this study, a liquid phase RF plasma generator was designed to study the degradation of trichloromethane and humic acid. The main conclusions are as follows: (1) the main free radicals produced in liquid radio frequency plasma are. OH and H by emission spectrum. When the conductivity range is 0.10~0.80mS/cm, the emission intensity of OH increases with the increase of conductivity. When the conductivity is in the range of 0.80~6.00mS/cm, the emission intensity of,. OH decreases with the increase of conductivity. (2) when the solution initial pH, is added with free radical scavenger, NO3- can increase the removal rate of CHCl3, HCO3- can play a buffer role and consume OH to increase H concentration indirectly. The main degradation intermediates are HCOOH,H2C2O4, CH2Cl2, H and eaq-, which are the key substances to initiate the dechlorination of CHCl3. It also plays an important role in the production and transformation of organic acids and dichloromethyl radicals, while OH mainly contributes to the degradation of organic acids. The final product is the partial high temperature during the discharge of CO2,H2O and HCl, and the enrichment and pyrolysis of CHCl3 are also helpful to its removal. The liquid-phase RF plasma technology can also effectively remove CH2Cl2, and the mechanism is similar to that of CHCl3. (3) the synergistic treatment of HA with H202 produced in solution by adding Fe2 has a good effect. The optimum pH range is 3.50 ~ 5.50, and when the initial concentration of HA is 30mg/L, The optimal concentration of Fe2 was 20mg / L, and the removal rate was 90.23.The removal rate of HA was 95.33 when the initial concentration of Fe2 was 20mg / L, 60mg/L, and the aromaticity of HA decreased after the discharge treatment. When the macromolecules are decomposed into small molecules, the strength of the hydroxyl group decreases, while the strength of-CH- increases.
【学位授予单位】：大连海事大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703
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