【作者】 王磊；

【导师】 于洪涛；

【作者基本信息】 大连理工大学 ， 环境工程（专业学位）， 2022， 硕士

【摘要】 近年来,芬顿技术在废水处理尤其是难降解有机污染物降解方面受到关注。但是均相芬顿技术存在需要酸性条件、产生铁泥、H₂O₂的产生和运输过程繁琐等限制。非均相电芬顿技术可以解决上述问题,但是传质效率低于均相反应导致反应速率较低。针对这个问题,本工作建立了负载FeOCl的微通道碳（MC）阴极的制备方法,构建了过滤式电芬顿反应器,研究其微通道内氧还原产H₂O₂、FeOCl活化H₂O₂产·OH和·OH降解有机污染物的速率,探讨了反应机制,并进行了反应器的放大研究。主要内容如下:碳化天然松木制备微通道碳电极,对其进行微观形貌观察、化学成分分析和电化学性能表征。长而直的通道有序排列,平均直径为28μm,FeOCl纳米颗粒均匀的分布在通道内表面。随着负载催化剂的前驱体溶液Fe Cl₃浓度的增加,生成FeOCl纳米颗粒的尺寸增加,当初始浓度为3.0 g/L时,FeOCl颗粒尺寸为50-300 nm,大小适宜不堵塞通道。循环伏安测试显示FeOCl-MC电极氧还原产H₂O₂电位为0.25 V vs.RHE,析氢反应起始电位约为-0.56 V vs.RHE,产H₂O₂电位范围宽,可有效避免副反应。以FeOCl-MC阴极为核心部件构建过滤式反应器,研究其降解污染物的性能。FeOCl-MC具有氧还原产H₂O₂和原位活化H₂O₂产·OH双功能,活性位点分别为微通道中的介孔碳和FeOCl纳米颗粒。在p H=3条件下,最佳电压和停留时间分别为-2.5 V和120 s。20 mg/L苯酚在此条件下10 min内去除率可达98%,显示此电芬顿反应器的良好性能。在p H=7条件下,电压和停留时间为-2.5 V和450 s时,20 mg/L苯酚10 min时去除率可达98%、TOC去除率为50%,阿特拉津和磺胺甲恶唑的去除率分别为79.3%、76.4%。运行8 h后苯酚去除率仍可达到92%,铁溶出量低于0.046 mg/L,显示良好性能和稳定性。自由基猝灭实验显示·OH是主要的氧化剂。对Fe（II）的再生机制研究表明H₂O₂和阴极电子共同参与Fe（II）再生。为了验证实用性,将电极放大到5 cm×10 cm,为提高O₂供应量,将溶液曝气改为O₂从电极孔道中曝入,并重新设计了有效体积210 m L的单元反应器,处理能力提升到0.3 L/h。大块电极H₂O₂的产量可达0.8 mmol/L,效果为溶液曝气的4倍。为进一步提高H₂O₂产量,将电极活化处理以提高含氧官能团的量（质量分数30%H₂O₂浸泡1 h）,产量提高到1.5 mmol/L。表明内曝气方式和含氧官能团在氧还原产H₂O₂中的重要性。综上所述,通过在微通道碳电极上负载FeOCl可以实现原位高效生产H₂O₂和·OH,并用于电芬顿降解有机污染物,此方法在废水深度处理领域具有应用可行性。更多还原

【Abstract】 In recent years,Fenton technology has attracted attention in wastewater treatment,especially in the degradation of refractory organic pollutants.However,the homogeneous Fenton technology is limited by acidic conditions,iron sludge generation,H₂O₂ generation and cumbersome transportation process.Heterogeneous electro-Fenton technology can solve the above problems,but the mass transfer efficiency is lower than the homogeneous reaction,resulting in a lower reaction rate.To solve this problem,a preparation method of microchannel carbon（MC）cathode loaded with FeOCl was established in this work,and a filter electro-Fenton reactor was constructed to research the rate of H₂O₂ production by oxygen reduction,activating H₂O₂ to produce·OH by FeOCl and the degradation of organic pollutants by·OH in microchannels.The reaction mechanism was discussed,and the scale up of the reactor was also studied.The main contents are as follows:Carbonized natural pine was used to prepare microchannel carbon electrode,and its microstructure,chemical composition and electrochemical performance was characterized and analyzed.The long and straight channels were arranged in order with an average diameter of28μm,and FeOCl nanoparticles were evenly distributed on the inner surface of the channels.With the increase of the concentration of progenitor solution Fe Cl₃,the size of FeOCl nanoparticles is increased.When the initial concentration is 3.0 g/L,the size was 50-300 nm,which was suitable and did not block the channels.Cyclic voltammetry showed that the potential of H₂O₂ produced by FeOCl-MC electrode was 0.25 V vs.RHE,and the initial potential of hydrogen evolution reaction was-0.56 V vs.RHE.The potential range of H₂O₂produced was wide,which could effectively avoid side reaction.The FeOCl-MC cathode was used as the core module to construct a filter reactor to study its performance for pollutant degradation.FeOCl-MC was a dual-functional cathode which could produce H₂O₂ and activate H₂O₂ to produce·OH in-situ.The active sites are mesoporous carbon and FeOCl nanoparticles in microchannels,respectively.At p H=3,the optimal voltage and residence time are-2.5 V and 120 s,respectively.Under these conditions,the removal rate of 20 mg/L phenol could reach 98%within 10 min,indicating the good performance of the electro-Fenton reactor.At p H=7,when the voltage and residence time were-2.5 V and450 s,the removal rates of 20 mg/L phenol and TOC was 98%and 50%,respectively,and the removal rates of atrazine and sulfamethoxazole were 79.3%and 76.4%at 10 min.After operating for 8 h,the phenol removal rate can still reach 92%,and the iron dissolution rate is lower than 0.046 mg/L,showing good performance and stability.Radical quenching experiments showed that·OH was the main oxidant.The regeneration mechanism of Fe（II）shows that H₂O₂ and cathodal electrons are involved in Fe（II）regeneration.In order to verify the practicability,the microchannel carbon electrode was enlarged to 5cm×10 cm.For more supply of O₂,the aeration mode was changed from solution aeration to which O₂ was aerated to the electrode channels.A unit reactor with effective volume of 210m L was redesigned,and the processing capacity was improved to 0.3 L/h.The yield of H₂O₂can reach 0.8 mmol/L,and the effect is 4 times that of solution aeration.In order to further improve the yield of H₂O₂,the amount of oxygen-containing functional groups in the electrode was increased by soaking electrode with 30%H₂O₂ for 1 h,and the yield was increased to 1.5 mmol/L.The results indicate that the importance of internal aeration and oxygen-containing functional groups in H₂O₂ reduction.In conclusion,loading FeOCl on microchannel carbon electrode can realize efficient production of H₂O₂ and·OH in-situ,and it can be used for degradation of organic pollutants by electro-Fenton.This method has application feasibility in the field of advanced wastewater treatment.更多还原