【作者】 张灿；

【导师】 龙腾锐； 方振东；

【作者基本信息】 重庆大学 ， 市政工程， 2008， 博士

【摘要】 TNT（2,4,6-三硝基甲苯）是重要的军事战略物资。TNT废水主要来源于TNT生产加工和废旧弹药处置过程,排放量大,而且难以生物降解,目前传统处理方法对TNT废水的降解尚未达到满意的效果。液中放电等离子体技术是近年来新兴的一种高级氧化技术,集高温热解、光化学氧化、液电空化降解、超临界水氧化等多种效应于一体,具有常温常压、高效、无选择性、无二次污染、能耗低等优点,在难降解废水的处理中具有明显的优势。本研究中自行研制了液中放电水处理试验装置,以TNT废水为研究对象,对液中放电降解TNT废水的影响因素、降解机理、联用工艺和降解产物分析等方面进行研究,得出以下主要结论。①系统研制了液中放电试验装置,比较了不同试验装置对TNT的降解效果。设计的高压脉冲系统可使普通低压电（220/380V）最高升至100kV。试验装置的接地电阻为0.86Ω,满足试验安全要求。设计并加工不锈钢圆柱体反应器（水平放电和垂直放电）,45^#碳钢圆柱体反应器;设计并加工四种形式电极,尖-尖式、尖-板式、多尖-板式、中空电极;设计并加工三种不同材质的尖-尖式电极,不锈钢、铜、碳钢。试验结果表明:45^#碳钢反应器对TNT的降解效果优于不锈钢反应器;研究的三种电极材料对TNT的降解效果依次为:铜>碳钢>不锈钢。多尖-板式电极对TNT的降解率最好,尖-尖式和尖-板式电极次之,中空电极最差。增长电极绝缘,减小电极裸露面积可提高降解效果。垂直放电反应器对TNT的降解效果优于水平放电。②采用45^#碳钢反应器、水平放电、尖-尖式45^#碳钢电极,进行液中放电等离子体对TNT模拟废水的降解试验,研究TNT降解的影响因素,并进行了动力学和能量效率分析。结果表明:在TNT初始浓度50.00mg/L、废水体积7L的条件下,300次放电后,液中放电对TNT降解率达到87.00%,TNT浓度降为6.50mg/L;放电500次后TNT降解率为91.20%,TNT浓度降为4.40mg/L,满足国家排放标准。液中放电等离子体降解TNT的反应符合表观一级反应动力学特征,活化能为14.5kJ/mol。本试验装置的能量效率G值为6.56×10^-2～　9.33×10^-2molecule/heV,具有较高的能量效率。③较深入地探讨了液中放电对水中污染物的降解机理。分析液中放电的原理和过程,概括了液中放电的降解模式,论证了液中放电中的高能电子轰击、高温热解、H₂O₂和O₃等物质的氧化、超临界水和超声空化效应的降解、冲击波、紫外光解、活性粒子氧化对有机物的降解作用,并测试了液中放电的流光光谱和活性物质的发射光谱。④进行了液中放电/纳米TiO₂、液中放电/通气对TNT废水的降解研究。利用溶胶-凝胶法制备纳米TiO₂粉体,对粉体进行表征,进行了液中放电/纳米TiO₂降解TNT的试验,研究TNT降解的影响因素。结果表明:在液中放电过程中投加纳米TiO₂可以提高降解效果。同样试验条件下,单独液中放电对TNT的降解率仅为63.00%;投加纳米TiO₂ 0.035g/L后,TNT降解率提高至90.47%。在液中放电试验装置的基础上设计了通气装置,采用通气电极（中空电极）,进行了液中放电/空气或臭氧对TNT的降解试验,并研究了TNT降解的影响因素。结果表明:在液中放电过程中通入空气或臭氧均可以提高降解效果。同样试验条件下,单独液中放电对TNT的降解率为59.80%;通入空气后TNT降解率为63.12%;通入臭氧后TNT降解率为82.95%。⑤在研究液中放电/Fenton试剂降解TNT废水的基础上,提出液中放电与铁屑内电解法协同降解TNT的方法。进行液中放电/Fenton试剂对TNT的降解试验,研究TNT降解的影响因素,结果表明:放电中单独添加H₂O₂或Fe2+均不能大幅度地提高TNT的降解效果,但同时添加H₂O₂、Fe2+（Fenton试剂）能大幅度地提高TNT降解效果。同样试验条件下,单独液中放电对TNT时降解率仅为63.00%,添加FeSO4 25.00mg/L,H₂O₂（30%V/V）0.50ml/L,TNT降解率为79.38%。进行液中放电/铁屑降解TNT的试验,研究TNT降解的影响因素,结果表明:同样试验条件下,单独液中放电对TNT的降解率仅为63.00%;投加铁屑40.00g/L,液中放电/铁屑协同处理TNT的降解率为92.16%,TNT浓度降为3.92mg/L,满足国家排放标准。液中放电/铁屑联用对TNT降解率高、可以减少放电次数、而且铁屑具有良好的重复使用性,具有应用于实际的可能。鉴于此,本论文推荐铁屑内电解法为液中放电降解TNT废水的最佳联用工艺。⑥研究液中放电降解TNT过程中CODcr、BOD5的变化,对TNT降解产物进行GC/MS联机分析,并探讨了TNT降解产物可能的生成途径。结果表明:放电300次后水样的TNT降解率为97.36%; CODcr去除率为34.29%。这说明在液中放电过程中TNT分子没有完全矿化,其中一部分仍以有机物的形式留在水中。放电前TNT模拟废水中的BOD5为“未检出”,放电50次以后的水样都检测出了BOD5,说明放电后水样中出现了可生化的有机物。GC/MS联机分析结果表明:TNT分子在液中放电中得到降解,有芳香族化合物（1,4-二甲苯、苯乙烯）和脂肪烃类结构有机产物（正十四烷、正十七烷）产生。更多还原

【Abstract】 TNT（2,4,6-trinitrotoluene） is an important material in military area. TNT wastewater from manufacturing process and disposing process is hardly biodegradable. The technique of electro-hydraulic discharge （EHD）developed in recent years including many effects such as high temperature pyrogenation, photochemistry oxidation, cavitation degradation, super-critical water oxidation, has advantages of normal temperature and press, high efficiency, no-selectivity, no-second pollution, low energy, and is efficient in disposing dis-biodegradable wastewater. The experiment installation of electro-hydraulic discharge was designed and established, and the influence factors, degradation mechanism, joins techniques, product analyse of TNT wastewater treatment by EHD was investigated. The results are as following:①The experiment installation of electro-hydraulic discharge was designed and established detailedly, and TNT degradation rate of different installation was compared. Power supply can generate pulse high voltage which ranged from 0 to 100kV. The grounding net was designed and laid, and grounding resistance was 0.86Ω, which can guarantee safe during the course of discharging. Stainless steel reactor （level and uprightness discharge） and 45# carbon steel reactor were designed and machined. Four type of electrode, such as point-point, point-plane, points-plane, hollow electrode, and three electrode material such as stainless steel, copper, 45# carbon steel were designed and machined. The results are as following: TNT degradation rate of 45# carbon steel reactor was better than stainless steel one’s; TNT degradation rate of three kinds of electrode materials which were investigated was copper >45# carbon steel > stainless steel. TNT degradation rate of points-plane electrode was highest, and the point-point electrode’s and point-plane electrode’s take second place, and hollow electrode’s was lowest. With the improvement of electrode inslution length, the bare area of electrode decreased, TNT degradation rate increased. TNT degradation rate of uprightness discharge was better than level discharge’s.②The EHD wastewater treatment apparatus was used to degrade TNT wastewater by using 45# carbon steel, level discharge, point-point electrode, and influence factors of TNT degaradion , kinetics and energy efficiency were investigated. The results showed: When TNT concentration was 50.00mg/L volume of wastewater was 7L, after 300 discharges TNT degradation rate was 87.00%, TNT concertration decreased to 6.50mg/L. after 500 discharges TNT degradation rate was 91.20%, TNT concertration decreased to 4.40mg/L, reached national discharge standard. TNT degradation reaction by EHD followed appearance first order kinetics, and the energy of activation was 14.5kJ/mol. The energy efficiency is high, G value reached to 6.56×10^-2～9.33×10^-2 molecule/heV.③Mechanism of EHD degrading aqueous organics was investigated. With the analysis of EHD principle and course, TNT degradation mode of EHD was summarized. The effects of EHD, such as high-energy electron, high temperature pyrogenation, oxidation of H₂O₂ and O₃, supercritical water and ultrasonic cavitation, shock waves, UV photolysis, oxidation of active particle. In addition, the spectrum of EHD streamer and spectrum of active particles during the experiment was tested.④Degrading TNT wastewater by EHD/Nanosized TiO₂,and EHD/aerate was investigated. Nanosized TiO₂ powder prepared by sol-gel method was characterized. TNT wastewater was degraded by EHD/Nanosized TiO₂ Photocatalysis and influence factors were investigated. Results showed that adding Nanosized TiO₂ to EHD can improve TNT degradation rate. When TNT concentration was 90.00mg/L,volume of wastewater was 7L, discharge times was 300, TNT degradation rate by EHD was 63.00%, adding 0.035g/L nanosized TiO₂ to EHD, TNT degradation rate reached 90.47%. According to the EHD experiment apparatus, aerate apparatus which can supply air or O3 was designed and machined. TNT wastewater was degraded by EHD/ air or O3, and influence factors were investigated. When TNT concentration was 50.00mg/L, volume of wastewater was 7L, discharge times was 300, ventilation electrode （medium-hollow electrode）, TNT degradation rate by EHD was 59.80%, TNT degradation rate by EHD/air was 63.12%, TNT degradation rate by EHD/ O3 reached 82.95%.⑤Degrading TNT wastewater by EHD/Fenton reagent was investigated, and the EHD/ Iron scraps degrading TNT wastewater was put forword. TNT wastewater by EHD/Fenton reagent was reaseached, and influence factors were investigated. Results showed that adding Fe2+ or H₂O₂ lonely to EHD cann’t improve TNT degradation rate, but adding Fe2+ or H₂O₂ together （ Fenton reagent ） to EHD increase TNT degradation rate greatly. Under the same experiment condition, TNT degradation rate by EHD was 63.00%, while adding FeSO4 25.00mg/L,H₂O₂（30%V/V）0.50ml/L to EHD, the degradation rate by EHD/ Fenton reagent was 79.38%. TNT wastewater by EHD/ Iron scraps was reaseached, and influence factors were investigated. Results showed that adding Iron scraps to EHD can improve TNT degradation rate greatly. Under the same experiment condition, the degradation rate by EHD was 63.00%, While adding iron scraps 40.00g/L, the degradation rate by EHD/Iron scraps was 92.16% , TNT concerntration was 3.92mg/L, reached national discharge standard. Because of the high degradation rate of EHD/Iron scraps , the less discharge times, and the more use times of iron scraps, the EHD/Iron scraps has more protential to be used in practice. Therefore, in this paper, the Iron scraps internal eletrolys was recommended to be the best join techics of EHD.⑥The change of CODcr, BOD5 during the course of EHD was investigated, and the degradation products were analyzed by GC/MS, and the possible degrading route of TNT was discussed. Results showed that after 300 discharges EHD reached 97.36% in TNT degradation and 34.29% in CODcr removal. That is to say, during the course of EHD, TNT haven’t been mineralized tollaly, many arganics still existed in the wastewater. The BOD5 of TNT wastewater before discharge was“not examined”, the BOD5 after 50 discharge increased. This showed the biograble argaices appeared after discharge. The GC/MS spectum showed that TNT was degraded by EHD, the degradation products includeed organic substance containing benzene（Benzene, 1,4-dimethyl, Styrene） and aliphatic hydrocarbons （Tetradecane, Heptadecane）.更多还原