Photolysis pathway of nitroaromatic compounds in aqueous solutions in the UV/H2O2 process

IntroductionNitrobenzene (NB) was mainly used in theproduction of aniline, also used as a solvent inpetroleum refining, as well as used in the manufactureof other organic compounds such as dinitrobenzenes,dichloroanilines and acetaminophen (WHO, 2003).Nit…     

Direct photolysis of nitroaromatic compounds in aqueous solutions

The direct photolysis of nitrobenzene and nitrophenols in aqueous solutions irradiated by polychromatic light were investigated. Several aromatic intermediates were identified as three nitrophenol isomers, nitrohydroquinone, nitrosobenzene, nitrocatechol, catechol and phenol. Nitrite and nitrate ions were also detected in the irradiated solution indicating direct photolysis of nitrobenzene or nitrophenols. The degradation of nitrobenzene and nitrophenols and the formation of three nitrophenol isomers were observed to follow zero-order kinetics. The quantum yields for nitrobenzene and nitrophenols removal are about 10^-3 and 10^-3—10^-4 respectively. The mechanism for nitrobenzene degradation was suggested to follow mainly nitro-nitrite intramolecular arrangement.     

UV/H2O2体系光降解邻苯二甲酸二丁酯研究

研究了邻苯二甲酸二丁酯(DBP)在UV/H₂O₂体系中的光降解.结果表明:DBP在UV/H₂O₂体系中能很好地降解,且其光降解速率大于在单一UV辐照下的光降解速率;在pH为中性条件下DBP的光降解速率最快,而在强酸性或碱性条件下DBP的光降解速率均较低;在一定H₂O₂浓度范围内,DBP的光降解速率随c(H₂O₂)的升高而增大,但当c(H₂O₂)过高时,其对·OH自由基的清除作用使DBP的光降解速率减慢.DBP的光降解速率随其初始质量浓度的增大而降低;在实验质量浓度范围内,DBP的光降解速率常数近似与其初始质量浓度成负一级反应动力学关系.      

UV/H2O2光化学氧化降解对氯苯酚废水的反应动力学

研究了UV/H2O2体系降解对氯苯酚废水的过程及动力学结果表明,反应降解速率与双氧水加入量、污染物初始浓度及载气种类有关.在双氧水理论投加量一半的情况下,通入氧气或空气,总酚的降解率可达到96%,CODCr去除率接近50%.反应体系加入载气,显著影响污染物的去除率.在本实验中,总酚降解为拟一级反应.     

UV/H2O2工艺降解水中17α-乙炔基雌二醇

采用UV/H2O2间歇式光氧化反应器去除饮用水中低浓度17α-乙炔基雌二醇(EE2).结果表明,在原水中EE2浓度约为650μg/L、UV光强154μW/cm2、H2O2投加量5mg/L、反应时间30min条件下,EE2的去除效率可达到90%;光降解过程符合拟一级反应动力学模型;EE2的光降解速率常数随着H2O2投加量和光强的增加而增加.较低的反应液pH值有助于EE2的光降解.UV/H2O2联用工艺对EE2的去除具有协同作用.阴离子HCO3-、NO3-、Cl-、SO42-对EE2光降解反应有抑制作用.     

UV/H2Ｏ2/微曝气联用工艺矿化内分泌干扰物BPA试验研究

采用UV/H₂Ｏ₂/微曝气工艺对水中内分泌干扰物双酚A(BPA)的降解与矿化进行了试验研究.该工艺是在UV/H₂Ｏ₂的基础上发展起来的一种新工艺,微曝气在UV光照射下产生了一定量的O₃,提高了·OH的发生率.本试验研究了UV光强、H₂Ｏ₂投加量以及pH值对BPA矿化速率的影响.结果表明,随着UV光强的增大,BPA的矿化速率呈线性增加;当H₂Ｏ₂投加量由5 mg/L增大到20 mg/L时,BPA矿化速率常数k由0.003 2上升到0.025 0;当pH为6.68时,在相同条件下BPA的矿化效果最好.在同一工况条件下,UV/H₂Ｏ₂/微曝气工艺降解BPA的速率远远大于其矿化速率,分析得出在开始反应阶段BPA首先被降解为小分子有机物,随着反应的进一步进行小分子有机物逐步被矿化为无机物.     

UV/H2O2降解水中硝基酚及影响因素

UV H2 O2 氧化对硝基酚实验表明 ,H2 O2 光解产生·OH自由基是对硝基酚降解的直接原因 ,12min内 2 5mg L的对硝基酚去除率达到98%以上。溶液中TOC变化与对硝基酚的去除并不同步 ,说明对硝基酚的降解中生成了一系列的中间产物 ,然后再达到完全矿化的。体系中H2 O2 浓度变化显示产生的中间产物对H2 O2 光解没有明显影响。研究中还对对硝基酚起始质量浓度、H2 O2 浓度及pH影响进行了考察。研究认为UV H2 O2 是对硝基酚脱毒的一种有效方法     

Comparison of degradation reactions of Acid Yellow 61 in both oxidation processes of H2O2/UV and O3

ＩｎｔｒｏｄｕｃｔｉｏｎＣｏｌｏｒｓｕｂｓｔａｎｃｅｓｉｎｄｙｅｉｎｇｅｆｆｌｕｅｎｔｓｎｏｒｍａｌｌｙｃａｕｓｅｃｅｒｔａｉｎｄｉｆｆｉｃｕｌｔｉｅｓｉｎｔｒａｄｉｔｉｏｎａｌｂｉｏｌｏｇｉｃａｌｔｒｅａｔｍｅｎｔｐｒｏｃｅｓｓｅｓｄｕｅｔｏｔｈｅｄｙｅｍｏｌｅｃｕｌｅｓａｒｅｈｉｇｈｌｙｓｔｒｕｃｔｕｒｅｄｐｏｌｙｍｅｒｓａｎｄｔｈｅｉｒｔｏｘｉｃｉｔｙ (Ｈａｍｚａ ,1980 ;Ｇｉｎｏｃｃｈｉｎｉｏ ,1984 ;ＭａＫａｙ ,1980 ) .Ｉｔｉｓｎｅｃｅｓｓａｒｙｔｏｉｍｐｒｏｖｅｔｈｅｔｒｅａｔｍｅｎｔｅ…     

UV/H2O2光化降解水中邻二氯苯的反应机理

通过UV/H2O2光化高级氧化法,对水中邻二氯苯的降解途径及机理,降解反应的影响参数进行了系统的研究.结果表明,光化降解邻二氯苯的反应迅速,弱酸性或中性环境较有利于降解反应的进行,H2O2的投入量在特定的条件下具有一个最佳值.采用离子色谱(IC)、GC/MS等方法鉴定出邻二氯苯降解的中间产物主要为2,3-二氯苯酚、3,4-二氯苯酚、2-氯苯酚、甲酸、乙酸、乙二酸等.依此推导出了邻二氯苯的UV/H2O2光化降解的途径和机理.     

UV/H2O2光催化氧化法处理表面活性剂废水

采用UV/H2O2光催化氧化法处理含表面活性剂废水,考察了反应时间、体系pH值、表面活性剂初始浓度、H2O2投加量、表面活性剂的种类等因素对处理效果的影响,并初步探讨了表面活性剂降解的反应动力学.结果表明,当初始pH值为4、H2O2投加量为1mL/L,反应时间为20min时,表面活性剂DBS的去除率为96%,AOS的去除率为93%,且UV/H2O2体系中,表面活性剂DBS和AOS的降解反应均符合表观拟一级反应动力学特征.     

UV/H2O2/草酸铁络合物光降解水中氯仿的研究

以４００Ｗ高压汞灯为紫外光源，Ｈ２Ｏ２－草酸铁络合物为光氧化剂，对氯仿水溶液进行了光降解反应实验研究．结果表明，ＵＶ／Ｈ２Ｏ２草酸铁络合物体系能有效地使水溶液中氧仿迅速光解脱氯；在等摩尔系列溶液中,Ｆｅ３＋／草酸根的摩尔比为１：３时，氯仿光解效果最好：溶液ｐＨ值对氯仿光解有显著影响，ｐＨ值在３－４时光解速率最快；随着Ｈ２ｏ２浓度的增加，氯仿大解速率提高，但Ｈ２Ｏ２浓度较大时，Ｈ２Ｏ２的有效利用率降低；温度对氯仿光解反应有一定影响，反应的表观活化能为７．６ｋＪ／ｍｏｌ.     

水质对UV/H_2O_2降解2,4-二氯酚的影响

研究了UV/H2O2工艺对2,4-二氯酚(2,4-DCP)的去除效果和水中阴离子、腐殖酸对该工艺降解2,4-DCP的影响。结果表明:UV/H2O2工艺可以有效的去除水中2,4-DCP,光降解过程符合一级反应动力学模型;在H2O2投加量为8mg/L,1个30W低压汞灯照射下,2,4-DCP在蒸馏水和自来水中光降解速率常数分别为0.0232/min和0.0162/min;NO3-、Cl-、HCO3-对2,4-DCP光降解有抑制作用;当3种离子浓度为0.5mmol/L、10mmol/L、20mmol/L时,对2,4-DCP光降解的抑制程度为HCO3->NO3->Cl-;随着离子浓度增大,抑制作用增强;自来水中的光降解速率常数低于蒸馏水中的光降解速率常数是由于水中多种离子影响的结果;腐殖酸在低浓度时,促进光降解反应的进行,在高浓度时,2,4-DCP的光降解氧化受到抑制。     

UV/H2O2法处理焦化废水的试验研究

焦化废水是一种典型的成分复杂的难降解有机废水。实验利用UV／H2O2法对焦化废水的处理进行研究,探讨了不同反应时间、H2O2投加量、pH值等因素对COD去除率及色度降解效果的影响。结果表明．废水起始COD质量浓度为1334mg几时,H2O2投加浓度为45mmol/L,pH值=11,紫外灯照射60min,COD去除率可达70％以上;随着H2O2投加量的增加以及pH值的升高,污水的色度明显降低。     

UV/H_2O_2工艺降解微囊藻毒素-LR

采用UV/H2O2联合工艺,研究了光强、初始浓度、H2O2投加量、pH及阴离子对微囊藻毒素-LR (MC-LR)去除率的影响.结果表明,单独H2O2对MC-LR基本无去除效果;单独UV工艺可以一定程度上降解MC-LR;而UV/H2O2联合工艺由于发生协同作用明显提高降解效率.试验发现,随着光强的增大,MC-LR的去除率不断提高;随着MC-LR初始浓度的增大,其去除率不断降低;随着H2O2投加量的增大,降解速率常数逐渐增大,当H2O2投加量由1 mmol/L增大到3 mmol/L时,降解速率常数由0.0844上升到0.1664;当pH为3.13时,在相同条件下MC-LR的去除效果最好;阴离子的投加不利于MC-LR的降解,其中CO2-3、NO-3影响最大.     

絮凝沉淀-H2O2/UV体系处理发制品废水的研究

研究了发制品废水经絮凝沉淀－H2O2／UV体系处理的可行性。结果表明，废水经处理后，COD去除率可达90％以上，色度去除率达100％，探讨了投药量、反应pH、反应时间等因素对COD去除率的影响，并比较了H2O2／F^2 、H2O2／UV、H2O2／Fe^2 ／UV三种体系的处理效果。     

UV/H2O2液相氧化净化烟气中NO的实验研究

采用UV/H₂O₂液相氧化技术净化气体中的NO,通过正交实验和单因素实验,研究了H₂O₂浓度、温度、初始pH值、NO浓度、光照条件、O₂含量和气体流量等因素对NO去除率的影响.结果表明,UV/H₂O₂液相氧化体系对NO有良好的净化效果,可以获得80%左右的NO去除率, 温度、H₂O₂浓度和初始pH值对NO去除率具有不同程度的影响,温度和H₂O₂浓度对NO去除率影响较大.单因素实验结果表明, 当H₂O₂浓度为0.2 mol/L、初始pH值为6～7时NO去除率较高;溶液中H₂O₂浓度过高或过低、溶液过酸或过碱均会抑制·OH的产生而不利于NO的去除;净化NO的最佳反应温度为40 ℃,低于一般湿法脱硝温度(50 ℃);NO的去除率随紫外光辐射强度和O₂含量的增加而升高;同时,NO的去除也受气液传质面积和气液传质系数的控制.     

UV／H2O2／GAC与GAC处理微污染水的研究

文章进行了UV／H2O2／GAC和GAC系统用于微污染水深度处理的试验研究,结果表明：UV／H2O2／GAC对uV篮;和TOC均有良好的去除效果,当H2O2投量3．0mg／L,UV／H2O2反应器停留时间20min时,系统的COD和UV254去除率为44．6％和72．8％。UV／H2O2主要作用在于改善了GAC对有机物的吸附,产生了羟基自由基,从而提高了去除效果。     

DBP formation from degradation of DEET and ibuprofen by UV/chlorine process and subsequent post-chlorination

The formation of disinfection by-products(DBPs) from the degradation of N,N-diethyl-3-methyl benzoyl amide(DEET) and ibuprofen(IBP) by the ultraviolet irradiation(UV)/chlorine process and subsequent post-chlorination was investigated and compared with the UV/H_2O_2 process.The pseudo first-order rate constants of the degradation of DEET and IBP by the UV/chlorine process were 2 and 3.1 times higher than those by the UV/H_2O_2 process, respectively, under the tested conditions. This was due to the significant contributions of both reactive chlorine species U(RCS) and hydroxyl radicals(HO) in the UV/chlorine process. Trichloromethane, 1,1,1-trichloro-2-propanone and dichloroacetic acid were the major known DBPs formed after 90% of both DEET and IBP that were degraded by the UV/chlorine process. Their yields increased by over 50%after subsequent 1-day post-chlorination. The detected DBPs after the degradation of DEET and IBP comprised 13.5% and 19.8% of total organic chlorine(TOCl), respectively, and the proportions increased to 19.8% and 33.9% after subsequent chlorination, respectively. In comparison to the UV/H_2O_2 process accompanied with post-chlorination, the formation of DBPs and TOCl in the UV/chlorine process together with post-chlorination was 5%–63% higher,Ulikely due to the generation of more DBP precursors from the attack of RCS, in addition to HO.     

Advanced treatment of oil recovery wastewater from polymer flooding by UV/H2O2/O3 and fine filtration

In order to purify oil recovery wastewater from polymer flooding （ORWPF） in tertiary oil recovery in oil fields, advanced treatment of UV/H2O2/O3 and fine filtration were investigated. The experimental results showed that polyacrylamide and oil remaining in ORWPF after the conventional treatment process could be effectively removed by UV/H2O2/O3 process. Fine filtration gave a high performance in eliminating suspended solids. The treated ORWPF can meet the quality requirement of the wastewater-bearing polymer injection in oilfield and be safely re-injected into oil reservoirs for oil recovery.     

O3/H2O2法降解甲基叔丁基醚（MTBE）的试验研究

采用自制鼓泡反应器对臭氧/双氧水(O3/H2O2)降解水中甲基叔丁基醚(MTBE)进行了试验研究,考察了进气(含O3)流量、H2O2 投加量、MTBE初始浓度、pH、温度等因素对MTBE降解的影响.结果表明,在MTBE初始浓度为10 mg·L-1,气体流量为0.5 L·min-1,温度293K, pH=6.5, H2O2 添加量为2.4mg·L1 条件下,反应30 min后, MTBE去除率可达75.5%, COD去除率为68.0%.降解得到的中间产物主要有叔丁基甲酯(TBF)、叔丁醇(TBA)、乙酸甲酯(MA)和丙酮(AC)等,据此探讨了O3/H2O2氧化MTBE的可能反应机理和降解途径.