【作者】 杨春维；

【导师】 王栋；

【作者基本信息】 大连理工大学 ， 环境工程， 2012， 博士

【摘要】 传统的生物处理技术对水中的生物难降解有机物去除效率较低时,高级氧化技术处理此类污染物可发挥反应速度快、处理完全、二次污染小、适用范围广等优点,可成为生物难降解有机废水治理的有效方法之一。在高级氧化技术中,Fenton技术相对稳定、简单、具有应用优势,得到了广泛关注。目前其去除特定难降解有机物的过程与机理有待具体深入研究,同时也存在实验室单底物模拟条件与实际水体复杂体系条件相差较大等问题,得到的结果在实际工程应用时应研究其他组分的影响。研究以Fenton与电Fenton方法降解单底物模拟废水作为比较基础,考察了单底物和双底物条件下Fenton与电Fenton降解水中有机污染物的动力学行为,并对多底物条件下Fenton技术降解水中有机物的机理进行了探讨。主要开展如下研究：(1)分别采用甲基橙和刚果红偶氮染料作为模型化合物,考察Fenton技术降解水相中模型化合物的动力学特征。结果表明Fenton技术降解模型化合物的反应过程可以用底物浓度准一级动力学来表征,在30℃-60℃范围内温度对Fenton技术降解目标化合物的影响不明显,说明该过程具有较宽的温度适应范围。通过溶液浸渍法制备出以活性炭为基础的非均相Fenton催化剂,在pH为2.0～5.0范围内均具有较高活性,反应30min降解脱色0.028mmol/L甲基橙溶液脱色率均可达90%以上,反应过程中Fe2+离子浓度稳定在1.5mmol/L以上。(2)通过溶液浸渍法可以将金属Ag单质负载于金属加工废料铁刨花上,制备出双金属阴极电极。实验条件下,Fe基负载金属Ag作为阴极,反应60min后H202生成量比石墨板阴极生成量增加了46.9%,体相中Fe2+浓度分别比石墨板阴极增加了10.6倍,说明通过电极的改性可以改善电Fenton反应的效率。开发设计出内循环塔式阴极电Fenton反应器(ICBR),相对于普通方形电解槽反应器降解脱色甲基橙溶液具有很好的效果,相同条件下,其一级动力学反应常数为方形电解槽反应器的5.39倍,铁刨花作为阴极用于内循环塔式阴极电Fenton反应器具有较好的经济性和实用性。(3)分别采用亚甲基蓝-苯酚和甲基橙-十二烷基硫酸钠(SDS)两类双化合物体系作为多底物模拟环境水相,并对其进行Fenton、电Fenton技术氧化降解实验。结果表明苯酚对亚甲基蓝溶液脱色的抑制效果影响明显,推测苯酚与亚甲基蓝的Fenton反应为并行竞争反应,苯酚占有优势,亚甲基蓝的毓基因为空间位阻的存在,加之苯环结构影响电子云变形,相对于苯酚不容易被氧化。在甲基橙-SDS体系中,当SDS小于临界胶束浓度时,甲基橙降解反应速率常数随SDS浓度的增加而下降,推测SDS与甲基橙在水溶液中发生水合反应,SDS阻碍甲基橙被直接进攻氧化。实验结果表明双底物条件下,目标化合物的降解会受到第二种模型化合物的影响,且影响行为与两种化合物的分子结构及亲电竞争能力有关。(4)考察了Fenton技术与电Fenton技术降解实际糠醛工业废水的效果,在10L反应器中的实验结果表明Fenton技术由于反应条件温和,pH值变化较小,降解效率高,FeSO4、H202和COD的初始质量比为2：1：10时,反应1小时COD从13000mg/L降为1900mg/L,可以作为糠醛废水的预处理手段。采用Fenton-混凝-PACT组合工艺处理糠醛废水,效果稳定,基本达到污水综合排放标准(GB8978-1996)中规定的二级排放标准,药剂费用4.96元/吨糠醛废水,投资费用较低,具有很好的环境效益和经济效益。本研究成果丰富了Fenton高级氧化技术理论,并为Fenton技术在工业废水处理应用中的过程控制提供了科学研究参考。更多还原

【Abstract】 Removal of refractory organics from industry wastewaters was difficult by biological process. Advanced oxidation processes (AOPs) are efficient for its fast reaction speed, high purification efficiency, less secondary pollution and wide application. Fenton process, which uses iron ions as homogeneous catalyst and hydrogen peroxide as oxidizing reagent, has attracted more and more attention for its relatively stable, simplicity, mild condition, and suitability for practical application although the reaction mechanism still need more in-depth studies. The dynamics of multiple organics pollutants degradation should be investigated for the results of laboratory scale studies differ greatly in complex system problems.This paper focused on dynamic behavior studies of Fenton and electro-Fenton process treatment of the single and dual organics pollutants in the aqueous phase to reveal the Fenton reaction characteristics in treating multiple organic pollutant substrates. The main resluts were as followed:(1) To investigate the dynamic behaviors of Fenton process, methyl orange and Congo red were selected as simulation target pollutant respectively. The kinetics modeling indicated the Fenton oxidation reaction of the targeted pollutants followed the pseudo first-order reaction. Variation of the rate constants was not obvious in the temperatures ranging from30℃to60℃. The process has a wide range of temperature adaptation. The heterogeneous Fenton catalyst based on activated carbon were made by solution immersion method. The decoloration efficiency of0.028mmol/L methyl orange solution could reach90%above even pH increased from2.0to5.0. The concentration of Fe2+could maintain1.5mmol/L above during the procedure.(2) Electro-Fenton oxidation simulation using methyl orange as the target pollutant was also studied. The Ag-Fe bimetal wires cathode were fabricated by solution immersion method using the iron scraps of a mechanical processing factory. The concentration of H2O2generated by Ag-Fe bimetal wires cathode was46.9%more than the graphite plate cathode in this research experimental conditions. The concentration of Fe2+by Ag-Fe bimetal wires cathode was10.6times as graphite plate cathode. The Ag-Fe bimetal wires cathode could enhance the efficiency of electro-Fenton reaction. Internal Circulation Batch Electro-Fenton Reactor (ICBR) had been used for these bimetal wires cathodes. In the same conditions the kinetics reaction constant of ICBR was5.39times as the the kinetics reaction constant of ordinary squaree electrolytic cell reactor. This ICBR was stable and efficient in treating the targeted pollutant.(3) Fenton process to treat the dual organics pollutants in the aqueous phase was studied with phenol-methylene blue and sodium dodecyl sulfate (SDS)-methyl orange as model pollutant respectively. The results indicated that the presence of phenol reduced Methylene Blue discoloration rates. The-OH was thought to be more effective towards phenol oxidation instead of methylene blue for the high steric resistance of hydrosulfuryl in methylene blue. The degradation rate decreased with concentration of phenol increased. SDS could reduce the methyl orange degradation rate during the Fenton process. The ion-associate complex compounds of SDS and methyl orange maybe formed in aqueous phase,-OH tended to degraded SDS instead of target pollutant methyl orange. The degradation rates of methyl orange were reduced by SDS during Fenton process when the concentration of SDS was below CMC (Critical Micelle Concentration). The results indicated that degradation process was affected by the second compounds in the system. The characteristic of dual degradation process was related to the molecular structures of compounds.(4) Treatment of furfural industry wastewater by Fenton and Electro-Fenton processes was investigated in this study using the reactor with10L volume. Results indicated that Fenton process was suitable for industrial pretreatment for its high efficiency degradation and mild conditions. On the optimum experiment results, the Fenton-coagulation-PACT process had been established to treat furfural wastewater. The COD of furfural industry wastewater could decrease from13000mg/L to1900mg/L when the initial mass ratio of FeSO4, H2O2and COD reached2:1:10with reaction1hour. The performance was stable during the experiment and effluents reached the second grade standard of GB8978-1996. The drug cost of this process to treat furfural wastewater has reached the Y4.96per ton furfural industry wastewater. This process also showed the advantages of lower capital construction costs and economic benefits.Results of the research had enriched the theory of Fenton advanced oxidation technology. It also provided the science references to process control of Fenton technology in industrial wastewater treatment.更多还原