【作者】 李林璘；

【导师】 康春莉；

【作者基本信息】 吉林大学 ， 环境科学， 2012， 硕士

【摘要】 持久性有机污染物（persistent organic pollutants,缩写POPs），由于在环境中很难降解，并具有高毒性，能持久的存在于环境中，并且由于其低水溶性和高脂溶性的特点，在环境中通过生物富集作用，最终会对人类的健康造成一定的威胁。六氯苯是持久性有机污染物之一，虽然现在已经禁止使用六氯苯，但作为农药生产五氯酚和五氯酚钠仍在使用。随工业生产排放的含六氯苯的废水和废气会影响生态环境，同时吸附在大气颗粒物上的六氯苯在环境中便于做远距离迁移，随着雨雪等又会重新回到陆地上，如此循环无论是对人类还是环境都造成了一定的威胁。因此，研究六氯苯的环境行为具有重要的意义，同时，太阳辐射地球上的生物的生命活动起到重要的作用，所以，研究六氯苯在环境中的光化学行为对分析六氯苯在环境中的变化行为具有一定的参考价值。目前对于六氯苯的环境行为的研究主要集中在沉积物和土壤，对于自然水体当中六氯苯的光化学行为研究甚少。本文主要以六氯苯为研究对象，模拟其在自然水体当中的的光化学行为，并讨论H₂O₂、K⁺、Na⁺、Fe²⁺、Fe³⁺、HCO₃^-、NO₃^-、NO₂^-、SO₄^2-对其光化学反应的影响，以及模拟太阳光/Fenton效应对六氯苯的影响，讨论六氯苯的光解机理。由于六氯苯具有较高的脂溶性，易于分配到有机质含量较高的介质当中，所以选取有机溶剂作为模拟植物表皮成分的反应介质来研究六氯苯在其表面的光化学行为。模拟六氯苯在自然水体中的光化学行为的实验中，在低压汞灯（紫外灭菌灯）的照射下HCB的光转化符合一级反应动力学模型，光解产物为五氯苯、1,2,3,5-四氯苯、1,2,3,4-四氯苯和1,2,4,5-四氯苯。UV/H₂O₂体系中HCB的光降解率是随着H₂O₂浓度的增大而增大，其光解产物是五氯苯、1,2,3,5-四氯苯、1,2,3,4-四氯苯和1,2,4,5-四氯苯。pH值是在7.48时，HCB的降解率最大；NO₂^-抑制了HCB的光降解；HCO₃^-和SO₄^2-对HCB的光降解影响不大；NO₃^-对HCB的光降解的作用随着浓度的变化而变化。在有机溶剂体系中根据表观反应速率常数得到HCB的光解速率为正己烷>甲醇>乙腈>丙酮，其光解机理均是还原脱氯的过程，正己烷体系中光解产物主要是五氯苯、1,2,3,5-四氯苯、1,3,5-三氯苯、1,3.4-三氯苯和1,3-二氯苯；在甲醇体系中光解产物主要是五氯苯，1,2,3,5-四氯苯和1,2,4,5-四氯苯；在乙腈体系中光解产物主要是五氯苯、1,2,3,5-四氯苯、1,2,4,5-四氯苯和1,3,4-三氯苯；在丙酮体系中光解产物主要产物五氯苯、1,2,3,5-四氯苯和苯。在水/有机溶剂（V:V）混合体系对HCB的光降解的影响中，有机溶剂为甲醇和乙腈的体系均是有机溶剂含量为0.2%最慢，有机溶剂含量为20%最快；在水/丙酮（V:V）混合体系中HCB的光降解速率随着丙酮含量的减小而增加，但当丙酮含量增加到一定程度时光解速率又表现为较快的形式。模拟太阳光/Fenton对HCB的氧化能力要远远高于Fenton、Fe²⁺或者H₂O₂单独对HCB的氧化能力。在模拟太阳光/Fenton体系中，NO₂^-和HCO₃^-抑制了HCB的光降解；NO₃^-对HCB光降解没有影响；强酸强碱均不利于HCB的光降解。更多还原

【Abstract】 Persistent organic pollutants（POPs）， because of their low photo-degradation,biodegradation,chemical degradation and high toxicity in theenvironment,POPs can abiding existence in the environment.Due to its low watersoluble and high fat soluble,and through the biological web in the environment,POPshave great harm to human health. Hexachlorobenzene（HCB） is one of the POPs,it isstill used to product the Pentachlorophenol（PCP） and Sodium pentachlorophenate（PCP-Na） despite their ban now. The waste water and waste gas containing HCBemissioned by the industrial production can influence the environment,and the HCBadsorbed in atmospheric particulates can make long distance migration and return tothe land with rain and snow,it can have great harm to human and environment withthis cycle.So,study the environmental behavior of HCB has the vital significance.Thesun radiation play an important role to the life on earth,so studying the photochemicalbehavior of HCB have great value to analysis the changes of HCB in theenvironment.For now,the research on nvironmental behavior of HCB are mainly focuson sediments and the soil,and seldom studies on nature water.The paper took the HCB as the research object,and carried out the research onthe photochemical behaviour of HCB in aqueous,and discussed the influence of somefactors on photoconversion of HCB,such as H₂O₂、K⁺、Na⁺、Fe²⁺、Fe³⁺、HCO₃^-、NO₃^-、NO₂^-、SO₄^2-and simulated sunlight/Fenton,and the reaction mechanism was alsodeduced.Because of it is high fat soluble,HCB can exist easily in the organic matter,sowe choose the organic solvent as simulation of the composition of plant skin to studythe photochemical behaviour of HCB.The photoconversion of HCB in aqueous phase by UV follows the first-orderkinetic reaction mode,the main production of the photoconversion of HCB in aqueousphase were Pentachlorobenzene,1,2,3,5-tetrachlorobenzene,1,2,3,4-tetrachlorobenze-ne and1,2,4,5-tetrachlorobenzene.The conversion rate of HCB increased with the increase of the initial concentration of H₂O₂, the main production of thephotoconversion of HCB in aqueous phase were Pentachlorobenzene,1,2,3,5-terachlorobenzene,1,2,3,4-tetrachlorobenzene and1,2,4,5-tetrachlorobenzene.The photoconversion of HCB was accelerated under the condition of pH=7.48; NO₂^-suppressed the photoconversion of HCB; HCO₃^-and SO₄^2-had little effect on thephotoconversion of HCB;the effects of NO₃^-on the photoconversion of HCB weredifferent with different concentration.The conversion rate of HCB in organic phase was n-hexane> Methanol>Acetonitrile> Actone.The photoconversion mechanism of HCB in organic phase wasreductive dechlorination. The main production of the photoconversion of HCB werePentachlorobenzene,1,2,3,5-terachlorobenzene,1,3,5-trichlorobenzene1,3,4-trichlor-obenzene and1,3-dichlorobenzene in n-hexane,and in Methanol werePentachlorobenzene,1,2,3,5-terachlorobenzene,1,2,4,5-terachlorobenzene,and inAcetonitrile were Pentachlorobenzene,1,2,3,5-terachlorobenzene,1,2,4,5-terachlorobenzene,1,3,4-trichlorobenzene. The main production of thephotoconversion of HCB in Actone were Pentachlorobenzene,1,2,3,5-terachloroben-Zene and Benzene.The conversion rate of HCB was high under the condition oforganic solvent content was20%while it was low under the condition of organicsolvent content was0.2%in Methanol and Acetonitrile; the effects of Actone on thephotoconversion of HCB were different with different concentration.The oxidability of simulation sun light/Fenton was stronger than Fenton, Fe²⁺andH₂O₂for HCB. NO₂^-, HCO₃^-, strong acid and alkaline conditions suppressed thephotoconversion of HCB; NO₃^-had little effect on the photoconversion of HCB underthe condition of simulation sun light/Fenton.更多还原