化学发光法测定Fenton反应中的羟自由基及其应用

建立了测定Ｆｅｎｔｏｎ反应中产生的羟自由基的化学发光法,酵母为发光底物,浓度为２４ｍｇ／ｍｌ,Ｈ２Ｏ２浓度为２４ｍｍｏｌ／Ｌ,ＦｅＳＯ４浓度为５．４ｍｍｏｌ／Ｌ,ｐＨ为２．８时,化学发光强度最大,即产生的羟自由基浓度最大。     

Differential anti-lipid peroxidative activity of melatonin

Scavenging activities of melatonin, which is a pineal secretory product and functions in circadian biology, and its related compounds against reactive oxygen species such as superoxide anion radical, hydrogen peroxide, hydroxyl radical and singlet oxygen as well as organic peroxide radical (t-BuOO”) were evaluated chemically by using electron spin resonance-spin trap and chemiluminescence methods. Antioxidative activity of the compounds was estimated by IC₅₀ value (µM), 50% inhibiting concentration of a compound against reactive oxygen species formed in each system, and the second-order rate constants (k₂) for the reactions of the compounds and superoxide anion radical or hydroxyl radical. Because melatonin has exhibited the highest scavenging activity against t-BuOO”, the biochemical anti-lipid peroxide radical scavenging activities of melatonin were examined. We found that melatonin exhibits higher anti-lipid peroxidative activity in the rat brain microsomes than in the rat liver microsomal and liposomal systems, suggesting that melatonin may function as a treatment for reactive oxygen species-related diseases of the brain.     

Self-catalytic degradation of ortho-chlorophenol with Fenton's reagent studied by chemiluminescence

The degradation of ortho-chlorophenol using Fenton's reagent was studied by chemiluminescence (CL). Without a special CL reagent, a weak CL emission from the mixture of ferrous ion and hydrogen peroxide was observed at room temperature. The CL intensity was increased by the addition of ortho-chlorophenol into the mixed solution. When the temperature was raised to 65℃, the CL intensity was enhanced strongly. The CL mechanisms for the system H₂O₂-Fe²⁺ with and without ortho-chlorophenol were studied by examining the CL spectrum, gas chromatography-mass spectrometry and electron spin resonance spectrum. The effects of various free radical scavengers, surfactants and fluorescence compounds on the CL intensity were also investigated. A self-catalytic oxidation mechanism was proposed. The results showed that singlet oxygen was the main emitter for the system H₂O₂-Fe²⁺. The strong CL from the system H₂O₂-Fe²⁺-ortho-chlorophenol was due to singlet oxygen and electronically excited quinone. The benzenediol-like intermediate product formed during the phenol oxidation process greatly promoted the Fenton's reaction and led to higher CL intensity. Chemiluninescence is a novel approach for the investigation of the oxidation of some organic pollutants by Fenton's reagent.     

紫外辐射H2O2与PMS氧化准好氧矿化垃圾床渗滤液尾水

采用紫外（UV）活化双氧水（H₂O₂）和过一硫酸盐（PMS）产生活性氧物种降解准好氧矿化垃圾床渗滤液尾水中有机污染物.结果表明,紫外辐射双氧水（UV-H₂O₂）和紫外辐射过一硫酸盐（UV-PMS）体系对有机污染物的降解相比于单独体系效果显著.初始pH值和氧化剂投加量能够显著影响2种体系的降解效能,增加氧化剂投加量能够一定程度提高2种体系对渗滤液尾水中有机物的去除;2种体系均在酸性条件下效果较好,初始pH值的升高对2种体系过程有机物降解有抑制作用并且对UV-H₂O₂体系的抑制尤为显著.在最优条件下（初始pH值为3,氧化剂投量为0.084mol/L）,UV-H₂O₂与UV-PMS体系处理后出水COD去除率分别达到了72.09%和56.22%.另外,UV-H₂O₂体系中主要活性氧物种是羟基自由基,而UV-PMS体系中主要是由羟基自由基和硫酸根自由基的共同作用.紫外-可见光谱与三维荧光光谱表明两体系中均能降解渗滤液尾水中难降解芳香类有机物质,并且UV-PMS较UV-H₂O₂体系对腐殖质的反应速率更快,但是两种体系对渗滤液尾水中腐殖质的降解途径存在显著差异.研究结果可为光化学氧化处理垃圾渗滤液中难降解有机物提供参考.     

Degradation of benzene derivatives in the CuMgFe-LDO/persulfate system: The role of the interaction between the catalyst and target pollutants

A novel insight on the role of interactions between target pollutants and the catalyst in the copper-containing layered double oxide(LDO)-catalyzed persulfate(PS) system was elucidated in the present study.4-Chlorophenol(4-CP),as a representative benzene derivative with a hydroxyl group,was completely removed within 5 min,which was much faster than the reaction of monochlorobenzene(MCB) without a hydroxyl group,with the degradation efficiency of 31.7% in 240 min.Through the use of radical quenching and surface inhibition experiments,it could be concluded that the interaction between 4-CP and CuMgFe-LDO,rather than free radicals,played a key role in the decomposition of 4-CP,while only the free radicals participated in the MCB degradation process.According to electron paramagnetic resonance and Xray photoelectron spectroscopy data,the formation of a Cu(II)-complex between phenolic hydroxyl groups and surface Cu(II) was primarily responsible for the degradation of phenolic compounds,in which PS accepted one electron from the complex and generated sulfate radicals and chelated radical cations.The chelated radical cations transferred one electron to Cu(Ⅱ) followed by Cu(I) generation and pollutant degradation successively.     

Determination of atmospheric hydroxyl radical by HPLC coupled with electrochemical detection

The hydroxyl radical (·OH) plays a central role in the oxidation and removal of many atmospheric compounds. Measurement of atmospheric·OH is very difficult because of its high reactivity and low atmospheric abundance. In this article, a simple and highly sensitive method, high performance liquid chromatography coupled with coulometric detection (HPLC-CD), was developed to determine·OH indirectly by determining its reaction products with salicylic acid (SAL), 2,3-dihydroxybenzoic acid (2,3-DHBA), and 2,5-dihydroxybenzoic acid (2,5-DHBA). Under the optimum conditions for its determination, 2,3-DHBA and 2,5-DHBA could be well separated and the detection limits for 2,3-DHBA were 3×10~(-10) mol/L and for 2,5-DHBA were 1.5×10~(-10) mol/L, which were lower than most previous reports. This method was also applied to measure atmospheric hydroxyl radical levels and demonstrated the feasibility in clean and polluted air.     

几种重金属对皱纹盘鲍血细活性氧产生的影响

体外条件下利用化学发光法定量地研究了不同种类和不同浓度的重金属:Cr、Cd、Hg、Pb、C和Zn对皱纹盘鲍血细胞吞噬时活性氧产生的影响。结果表明,不同种类和不同浓度的重金属浸泡急性处理皱纹盘鲍血细胞都不同程度地抑制了血细胞吞噬时的化学发光,表明重金属能够抑制皱纹盘鲍血细胞吞噬活动中的活性氧(ROS)的产生,而且这种抑制作用随着重金属浓度的增加而加强。不同的重金属抑制强度不同,从强到弱以次为Hg>Cd>Cu>Pb>Cr>Zn。研究表明六种重金属中,Hg对皱纹盘鲍血细胞的免疫毒性最大。     

One-step preparation of a novel graphitic biochar/Cu0/Fe3O4 composite using CO2-ambiance pyrolysis to activate peroxydisulfate for dye degradation

Herein,a one-step co-pyrolysis protocol was adopted for the first time to prepare a novel pyrogenic carbon-Cu⁰/Fe₃O₄ heteroatoms (FCBC) in CO₂ ambiance to discern the roles of each component in PDS activation.During co-pyrolysis,CO₂ catalyzed formation of reducing gases by biomass which facilitated reductive transformation of Fe³⁺ and Cu²⁺ to Cu⁰ and Fe₃O₄,respectively.According to the a...     

几种光化学体系中羟自由基的产生和测定

在人工光源照射下,以水杨酸为探针性物质,探讨了过氧化氢(H_2O_2)、二氧化钛(TiO_2)、亚硝酸钠(NaNO_2)、硝酸钠(NaNO_3)和杂多酸盐(PW_(12)O_(40)~(3-))等5种光化学体系中羟自由基的产生,并测定了羟自由基的稳态浓度。     

Toxic effects of chlortetracycline on maize growth, reactive oxygen species generation and the antioxidant response

The toxicity of chlortetracycline (CTC) on maize (Zea mays L.) growth and reactive oxygen species (ROS) generation was studied. The root and shoot lengths and fresh weights of maize seedlings were inhibited by CTC treatment (p < 0.05). Root length was more sensitive than other parameters with the EC₁₀ value of 0.064 mg/L. The spin trapping technique followed by electron paramagnetic resonance (EPR) analysis was used to quantify the ROS production. The ROS generated in maize roots after exposure to CTC was identified as hydroxyl radical (.OH). The EPR signal intensity correlated positively with the logarithm of CTC concentrations exposed (p < 0.05). The dynamic changes of malondialdehyde (MDA) contents and the antioxidative enzyme activities in maize roots were also determined. As compared to the control group, CTC was found to significantly increase MDA content. Treatment of maize roots with the.OH scavenger sodium benzoate (SB) reduced the MDA content and enhanced the antioxidative enzyme activities. The results demonstrated the harmfulness of CTC at high dose to maize in the early developmental stage, and clarified that the inducement of.OH is one of the mechanisms of CTC toxicity.     

多相流染料废水的臭氧高级氧化脱色行为研究

以亚甲基蓝(MB)模拟染料废水,研究了多相流中染料的臭氧氧化脱色动力学,考察了活性炭、缓冲条件下的pH值以及羟基自由基(.OH)捕获剂对染料脱色行为的影响。试验结果表明,染料MB的臭氧氧化脱色过程符合伪一级动力学。活性炭的相界面催化作用能够促进染料的脱色,当颗粒状活性炭(GAC)浓度由3 g/L增大至15 g/L时,脱色速率呈现增大的趋势,且粉末状活性炭(PAC)催化脱色能力更强。缓冲条件下的pH增大,脱色速率明显加快,而且添加活性炭(>9 g/L)比自由基较活跃(pH=12.7)时的脱色速率常数k提高了一倍。强碱性(pH=12.7)缓冲条件下加入足够量(0.003 mol/L)羟基自由基捕获剂,结果表明HCO3-捕获自由基的能力强于叔丁醇,但由于捕获剂对自由基反应路径的控制作用依然有限,导致染料的脱色速率仍比酸性(pH=2.5)条件下快。     

秸秆活性炭活化过一硫酸盐降解酸性橙7

将磷酸氢二铵((NH_4)_2HPO_4)作为活化剂制备秸秆活性炭(SAC),并用其活化过一硫酸盐(PMS)产生硫酸根自由基(SO_4~-·)降解偶氮染料酸性橙7(AO7).首先对活化前后的SAC进行FTIR表征,发现(NH_4)_2HPO_4活化后的SAC含氧官能团特征峰强度增强,可能有利于过一硫酸钾的活化.其次研究了活化剂浓度、SAC投加量、PMS浓度、初始pH、抑制剂对AO7降解效果的影响.结果表明,AO7脱色率随着活化剂浓度、SAC投加量、PMS浓度的增加而增加;同时在偏中性条件下,有利于SAC活化PMS脱色AO7;加入相同物质的量比(2000/1)的甲醇、叔丁醇、苯酚,55 min内AO7脱色率分别为88.4%、66.2%、13.4%,苯酚对反应抑制效果最好,表明SAC表面的硫酸根和羟基自由基在AO7脱色中起主要作用.最后通过紫外光谱扫描、气质联用(GC-MS)和TOC分析表明,AO7的偶氮键和萘环结构被破坏,生成含苯环类中间产物,最终矿化为二氧化碳和水,矿化率可达31.7%.     

Determination of photochemically-generated reactive oxygen species (ROS) in natural water

Reactive oxygen species (ROS) can be produced by interactions between sunlight and light-absorbing substances in natural water environment. ROS may participate in the indirect photolysis of trace organic pollutants, therefore resulting in the changing of their environmental fates and ecological risks in natural water system. Bisphenol A (BPA), an endocrine-disrupting chemical, exits widely in natural water. The photodegradation of BPA promoted by ROS (·OH, 1O2, HO2·/O2·-) which were produced on the excitation of ubiquitous constituents (such as nitrate ion, humic substances and Fe(III)-oxalate complexes) in natural water under simulated solar radiation was investigated. Both molecular probe method and electron spin resonance (ESR) test were used for the determine the characterization of generated ROS. It was found that ·OH was photochemically produced with the presence of nitrate ion, humic substances and Fe(III)-oxalate complexes and 1O2 was produced with the presence of humic substances. The steady-state concentrations of ·OH was 1.27×10-14 mol/L in nitrate ion, and the second-order rate constant of BPA with ·OH was 1.01×1010L/( mol·s).     

流动注射化学发光抑制法测定水样中L-甲硫氨酸的含量

在碱性条件下,过氧化氢氧化鲁米诺产生化学发光,本文系统讨论了L-甲硫氨酸对Luminol-H2O2-CTAB化学发光体系的影响,发现在一定条件下,L-甲硫氨酸对Luminol-H2O2-CTAB化学发光体系有较强的抑制作用。据此建立了流动注射化学发光法测定L-甲硫氨酸的分析方法。该法简单、快速、灵敏度高。测定L-甲硫氨酸的线性范围为1.0×10-7～5.0×10-5mol/L,检出限为7.8×10-8mol/L。对1.0×10-5mol/l的L-甲硫氨酸进行9次平行测定,得该法的相对标准偏差为3.2%。成功地用于水样中L-甲硫氨酸的测定,结果满意。     

Comparison of physiological responses to oxidative and .heavymetal stress in seedlings of rice paddy, Oryza sativa L.

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活性氧的化学发光测定法

以作者近年来的研究结果为中心 ,综合地介绍过氧化氢 (H2 O2 )、单线态氧 ( 1O2 )、超氧阴离子自由基 ( .O-2 )以及羟自由基 ( .OH)等活性氧化学发光研究的最新动态 .侧重介绍活性氧的鲁米诺、光泽精、甲壳动物荧光素化学发光测定体系 ,比较了这几种方法的各自特点和应用情况     

超声波/零价铁协同体系作用机理探讨

在超声波/零价铁协同体系中,探讨了OH.的产生途径及其影响因素,并分析了Fe0表面形态变化。结果表明:在超声波/零价铁体系中,羟基自由基的产生途径主要有四种:声空化导致水分子热解、Fenton反应、超声波与类Fenton反应的复合效应、铁粉颗粒效应;pH值过低或过高都不利于羟基自由基产生;当铁粉投加量为2.0g/L时最有利于羟基自由基产生;超声波通过冲刷、碎裂、清洗、气蚀和熔合等多种效应,活化和增强铁粉的表面性能。     

天水大气降尘矿物与水作用产生羟基自由基研究

利用高效液相色谱法测定了甘肃天水市麦积镇降尘与水作用产生羟基自由基(·OH)的能力,并根据降尘中主要矿物的百分含量对降尘与水作用产生·OH进行理论和混合模拟.结果表明,天水降尘中的主要矿物组成为石英,方解石,钠长石,白云母.降尘及组成矿物成分与模拟降尘与水作用产生·OH能力大小顺序为:方解石(1.30×10^-10 mol)>理论模拟降尘(5.47×10^-11 mol)>降尘(5.34×10^-11 mol)>石英(2.90×10^-11 mol)>白云母(1.90×10^-11 mol)>钠长石(1.09×10^-11 mol)>混合模拟降尘(7.16×10^-12 mol).降尘中的矿物成分是降尘与水作用产生·OH的主要贡献者.降尘中矿物的组成和在水溶液中金属离子与有机物的溶出,降尘与水作用时的接触表面积,矿物组分之间水溶液中的相互作用,可能是导致降尘,混合模拟降尘,理论模拟降尘三者与水作用产生·OH量有所差异的原因.     

Interfacial mechanisms of heterogeneous Fenton reactions catalyzed by iron-based materials: A review

The heterogeneous Fenton reaction can generate highly reactive hydroxyl radicals(·OH)from reactions between recyclable solid catalysts and H_2O_2 at acidic or even circumneutral pH.Hence,it can effectively oxidize refractory organics in water or soils and has become a promising environmentally friendly treatment technology.Due to the complex reaction system,the mechanism behind heterogeneous Fenton reactions remains unresolved but fascinating,and is crucial for understanding Fenton chemistry and the development and application of efficient heterogeneous Fenton technologies.Iron-based materials usually possess high catalytic activity,low cost,negligible toxicity and easy recovery,and are a superior type of heterogeneous Fenton catalysts.Therefore,this article reviews the fundamental but important interfacial mechanisms of heterogeneous Fenton reactions catalyzed by iron-based materials..OH,hydroperoxyl radicals/superoxide anions(HO_2./O_2~-.)and high-valent iron are the three main types of reactive oxygen species(ROS),with different oxidation reactivity and selectivity.Based on the mechanisms of ROS generation,the interfacial mechanisms of heterogeneous Fenton systems can be classified as the homogeneous Fenton mechanism induced by surface-leached iron,the heterogeneous catalysis mechanism,and the heterogeneous reaction-induced homogeneous mechanism.Different heterogeneous Fenton systems catalyzed by characteristic iron-based materials are comprehensively reviewed.Finally,related future research directions are also suggested.     

Fe3+或Fe2+均相催化H2O2生成羟基自由基的规律

利用电子自旋共振-自旋捕集技术(ESR)研究了不同条件下Fenton和类Fenton反应中羟基自由基的变化规律.结果表明,Fenton和类Fenton在起始反应阶段羟基自由基的生成速率都随着H₂O₂和Fe³⁺或Fe²⁺浓度的增大而增大,但Fenton反应在起始阶段羟基自由基生成速率显著高于类Fenton反应.Fenton反应pH在2.5～3.5,而类Fenton反应pH在2.8～3.0范围内有较高的自由基生成速率.起始反应完成后,反应过程中Fenton与类Fenton反应自由基的生成速率也存在显著差异.结果表明,两体系在反应起始和反应过程中都存在着机制的差异.