【作者】 杨龙誉；

【导师】 侯惠奇；

【作者基本信息】 复旦大学 ， 环境科学， 2008， 硕士

【摘要】 本文采用隔膜电解槽法,以硝基苯和罗丹明B为研究对象,研究了电解过程中阴极区的降解过程.并分别研究了阴极区在有溶解氧和无溶解氧条件下的降解情况。另外,作为对比实验,研究了研究区降解罗丹明B的情况。用硝基苯为研究对象,研究了阴极区OH以及H与硝基苯的反应机理。研究结果表明:通过实验表明,电解过程中硝基苯以及它的电解产物的挥发量很少,这些有机物的挥发而导致电解液中COD的减少可以忽略不计;同时,本实验采用的隔膜的隔离效果良好,在有电流的情况下,能有效地防止了有机物的滲透。在电解液罗丹明B初始浓度为50 mg/L,电解液初始pH=5.3,电解质Na₂SO₄浓度1g/L,外加电压20 V以及电解时间2 h的条件下,有溶解氧电解时,罗丹明B的脱色率和COD_Cr去除率分别为45%和21%,相比于无溶解氧条件下的40%和15%。在硝基苯初始浓度120 mg/L,外加电压20 V,初始pH=5.3,电解质Na₂SO₄浓度0.025 mol/L以及电解时间2 h的条件下,有溶解氧时,阴极区硝基苯COD_Cr去除率为36%,而无溶解时则为16%。硝基苯和罗丹明B的电解降解基本都是准一级反应。各影响因素对有机物的降解有着不同的影响:随着外加电压的增加,有机物的去除率有显著的增加;在低浓度范围内,随着电解液初始浓度的增加,有机物的去除率也在增加;不同电解液初始pH条件下,有机物的降解效果为:强酸＞弱酸和弱碱＞强碱,并且,在弱酸或弱碱范围内,电解液初始pH对有机物的降解几乎没有影响;随着电解质浓度的增加,有机物的去除率先快速增加,然后再缓慢减少。有机物在阴极区的电解降解机理为:电解时,水中的H⁺得到电子,变成H,H原子与电解液中的氧分子快速发生反应,生成强氧化性的HO₂和OH,或H直接与硝基苯反应生成C₆H₅NO₂-H adduct;生成的OH大部分能与硝基苯发生反应生成C₆H₅NO₂-OH adduct,C₆H₅NO₂-OH adduct又能与O₂进一步作用生成C₆H₅NO₂-OHO₂,而C₆H₅NO₂-H、C₆H₅NO₂-OH和C₆H₅NO₂-OHO₂均十分不稳定,它们都将迅速发生转化。其中C₆H₅NO₂-H有可能进一步生成苯胺、联苯类还原性物质,C₆H₅NO₂-OH和C₆H₅NO₂-OHO₂的后续反应则可能生成氧化态的物质。更多还原

【Abstract】 With the method of membrane electrolysis cell,this paper studied the electrolytic degradation of Nitrobenzene（short for NB） and Rhodamine B（short for RhB） on cathodal room.It also talked about the electrochemical deoxidization characteristics of organics on cathodal room on the present of dissolved oxygen and without the prensent of dissolved oxygen.As a contrastive experiment,it also focused on the electrochemic degradation of RhB on the room of anode.It studied the reaction mechanism of NB with OH and H on cathodal room.The results showed:The experiment showed that,the volatilization of NB and its products during the process of eletroclysis is too little to be ignored;the membrane used in the study was so good that it can avoid the infiltration of organics during the electrolysis.On the condition of applied voltage 20 V,the original pH of the electrolyte 5.3,the concentration of electrolyte Na2SO41 g/L,concentration of RhB 50 mg/L,electrolysis time 2 h and with the present of dissolved oxygen,the removal rate of RhB and COD_Cr is 45%and 21%respectively,contracting to that of 40%and 15%without the prensent of dissolved oxygen.On the condition of applied voltage 20 V,the original pH of the electrolyte 5.3, the concentration of Nitrobenzene 120 mg/L,the concentration of electrolyte Na₂SO₄ 0.025 mol/L,electrolysis time 2 h,and with the present of dissolved oxygen,the removal rate of COD_Cr was 36%,contracting to that of 16%without the prensent of dissolved oxygen.The electrolytic degradatons of NB and RhB belonged to pseudo-first order reaction.And different factors had different effect on the degradation of organics.The electrolytic reaction mechanism of cathodal room was:during the courses of electrolysis,the H⁺ of H₂O get an electron,become H.H and O₂ react quickly in the electrolyte,and make HO₂ and OH,which are strong active.HO₂ and OH can oxidate NB.更多还原