Al/H_2O_2体系氧化降解甲基橙

考察了Al/H_2O_2体系对甲基橙(MO)的氧化降解行为,探讨了Al粉、H_2O_2投加量、溶液初始pH以及共存阴离子等因素对MO降解的影响,并利用荧光光谱法通过证实·OH自由基的形成对降解机理进行了初步探讨.结果表明,Al/H_2O_2体系对MO的降解受溶液pH影响较大,在初始pH 3.0,铝粉投加量为4.8 g·L~(-1),H_2O_2投加量为7.2 mmol·L~(-1),对于含MO 20 mg·L~(-1)的染料废水,10 h MO降解率可达95.2%,而当初始pH3.5时,MO的降解被强烈抑制.无机阴离子(Cl~-、SO_4~(2-)、NO_3~-)单独存在时,对Al/H_2O_2体系降解MO影响较小,MO降解率仍可达90.0%以上.无机阴离子(Cl~-、SO_4~(2-)、NO_3~-)共同存在时,对Al/H_2O_2体系降解MO具有叠加效应,MO降解率仅达60.0%左右.Al/H_2O_2体系重复利用性能良好,对MO降解经7个周期后,降解率仍可达92.0%.降解机理研究表明,Al/H_2O_2体系氧化降解MO过程中,·OH发挥了主要作用.     

模拟日光-非均相Fenton光催化降解喹啉

以铝-分子筛(Al-MCM-41)为载体,采用加热回流法制备一种非均相芬顿催化剂还原氧化石墨烯-羟基铁/Al-MCM-41(r GO-Fe OOH/Al-MCM-41).以喹啉模拟有机废水,考察该催化剂在不同氧化体系、不同H_2O_2投加量、不同催化剂投加量和不同水质因素(喹啉初始浓度和p H值)条件下对喹啉降解效能的影响,同时考察了催化剂的重复使用性.结果表明,喹啉的光芬顿降解过程符合准一级反应动力学,降解过程中溶液中的NO-3浓度先升高后下降,表明喹啉的吡啶环被打开.对比芬顿反应,模拟日光芬顿反应中光的引入促进羟基自由基的产生,使得喹啉去除率由45%提高到了99%;喹啉降解速率随着催化剂和H_2O_2投加量的增加而升高,但投加量过多会消耗·OH自由基从而抑制喹啉降解,在光芬顿体系中,该催化剂在p H=3.6—9.6的范围内都表现出了很高的活性;当喹啉初始浓度为20 mg·L~(-1),催化剂投加量为0.5 g·L~(-1),H_2O_2投加量为20 mmol·L~(-1),p H=6.3时,该催化剂对喹啉有很好的矿化效果(TOC去除率为3%).催化剂重复使用性能稳定,重复使用5次喹啉去除率仍高达99%,但TOC去除率略有降低,铁溶出率为0.48%以下.     

UV/H_2O_2技术对上海青草沙水源水砂滤后溴酸根和三卤甲烷的生成控制

针对含溴离子(Br-)的上海某水厂滤后水的高级氧化处理,考察了紫外/过氧化氢(UV/H_2O_2)技术对UV254和总有机碳(TOC)的削减效率、控制消毒副产物溴酸根(Br O-3)和三卤甲烷(THMs)的生成情况,同时研究了水中溴离子(Br-)浓度的改变对UV/H_2O_2处理效果的影响.结果表明,UV/H_2O_2处理工艺不产生Br O-3;500 m J·cm-2的UV剂量和5 mg·L-1H_2O_2投加量下,出水UV254和TOC分别降低了35%和21%;后续氯消毒过程中的THMs生成势随H_2O_2投加量的增加显著降低,500 m J·cm-2的UV剂量下,H_2O_2投加量为5 mg·L-1和10 mg·L-1时,THMs生成势的削减率分别为49.4%和79.9%;水中Br-浓度的改变不影响UV/H_2O_2工艺的运行效果;相比UV,UV/H_2O_2还可使9种农药的降解率提高50%—85%.因此,UV/H_2O_2在含Br-水源水深度处理方面有着较好的应用前景.     

两级Fenton法预处理高浓度高色度铜拉丝乳化液实验研究

金属线材厂拉制线材用的铜拉丝油由基础油(矿物油、植物油和合成油)、乳化剂、抗氧化剂、抗泡剂等物质组成,能与水形成稳定的乳化液,主要起冷却、润滑、清洗、防锈等作用,经冷热交替和微生物降解会导致其变质,需要周期性的更换,产生需要处理的废乳化液。废乳化液量随着线缆行业的快速发展越来越多,该废液呈蓝色且有机物浓度高,若排放将对周围环境产生严重污染,经过处理达标排放成为该类企业的当务之急。Fenton氧化法是一种高级氧化技术,在酸性条件下,H_2O_2被Fe~(2+)催化分解并产生大量具有强氧化性的·OH,通过·OH氧化降解废水中的有机物,达到废水净化的目的。在处理有毒有害难生物降解有机废水方面具有较强的应用优势;本研究采用两级Fenton氧化法对高浓度高色度铜拉丝乳化液进行预处理,通过实验研究了H_2O_2和FeSO_4投加量、初始反应pH值、反应时间等因素对该废水处理效果的影响。结果表明,首级Fenton法处理废水的最佳反应条件为:pH值为2、H_2O_2(质量分数30%)投加量为140 mL·L~(-1)、FeSO_4(质量分数10%)投加量为96mL·L~(-1)和反应时间为40 min;二级Fenton氧化法考察了H_2O_2及FeSO_4投加量、反应时间等因素处理首级Fenton上清液的情况,结果表明:H_2O_2(30%)投加量为144 mL·L~(-1),FeSO_4(10%)投加量为192mL·L~(-1),初始反应pH值为2,反应时间为80min。原水COD约40000mg·L~(-1)降低到2000mg·L~(-1)以下,COD去除率高达95%,颜色从蓝色变成了无色,满足了后续生化处理对进水浓度的要求。为解决同类高浓度铜拉丝乳化液废水预处理提供了技术参考。     

μ-H_2O-桥联均相铁(Ⅲ)催化剂的合成及其对邻苯二甲酸二丁酯的降解性能

合成了μ-水桥联的双核铁(Ⅲ)配合物[Fe_2(μ-H_2O)(TS)_4(H_2O)_2]_2Cl_4·4H_2O](μ-H_2O-Fe(Ⅲ)-TS)(TS=N,N'-triethylentetramine-salicylideimine;即三乙烯四胺水杨醛亚胺),并以其为催化剂、通过类Fenton反应考察了其对邻苯二甲酸二丁酯(DBP)的催化降解性质.结果表明,μ-H_2O-Fe(Ⅲ)-TS在可见光条件下即可对DBP进行高效催化降解.采用UV-vis谱监测了μ-H_2O-Fe(Ⅲ)/DBP/可见光体系在加入H_2O_2前后不同时间的光谱,结果表明催化剂的活性位点可能为Fe(Ⅲ)-H_2O-Fe(Ⅲ)中心,形成了有利于H_2O_2活化的Fe(Ⅲ)-H_2O-Fe(Ⅲ)-H_2O_2过渡态,使得·OH可以在可见光作用下便可产生.降解实验研究表明,在pH值3.0—8.0范围内,μ-H_2O-Fe(Ⅲ)-TS的浓度为1.16—11.56μmol·L-1,H_2O_2的浓度为0.408—40.8 mmol·L-1,μ-H_2O-Fe(Ⅲ)-TS/H_2O_2/可见光体系均能在5 min内对浓度为14.39—143.88μmol·L~(-1)的DBP实现近100%降解,较普通Fenton反应体系有更宽的pH适用范围.μ-H_2O-Fe(Ⅲ)-TS可循环使用,是有优异潜力的水中DBP绿色降解催化剂.     

载铁沸石分子筛催化降解地下水中氯代烃的影响因素及机制研究

氯代烃是工业场地地下水中常见污染物,高效去除氯代烃是目前环境科学研究的热点。以负载铁的沸石分子筛(Fe-ZSM-5)为催化剂,研究Fe-ZSM-5催化降解三氯乙烷(TCE)的影响因素及降解机制。结果表明,在Fe-ZSM-5体系中,加入0.8 g·L~(-1) Fe-ZSM-5、10 mmol·L~(-1) H_2O_2、0.9 mmol·L~(-1) TCE、初始pH值为7.4、25℃条件下,TCE降解率可达88%,且随着催化剂用量和H_2O_2浓度的增大,同一浓度TCE的去除率逐渐升高,降解率最高可以达到99%。此外,改变溶液初始pH值,对TCE的降解无显著影响。与Fe-ZSM-5体系相同条件下,未负载铁的沸石分子筛(ZSM-5)体系催化H_2O_2降解TCE的去除率仅为41%,H_2O_2浓度从6增至14 mmol·L~(-1),TCE去除率反而降低,溶液初始pH对去除率也无显著影响。自由基猝灭试验发现,在Fe-ZSM-5催化体系中,羟基自由基(·OH)对TCE的降解起主导作用,而未负载铁的ZSM-5催化体系中,·OH的作用则不明显。     

氨基比林的臭氧降解和矿化效能分析

以氨基比林(pyramidon,PD)为代表性药物和个人护理品污染物,探讨了实验室条件下臭氧(O_3)氧化对PD的去除效果、动力学和降解机制,考察了反应条件包括温度、p H、阴离子和过氧化氢(H_2O_2)对PD降解过程的影响.结果表明,O_3氧化对PD的降解效果明显,降解过程符合拟一级反应动力学模型.降解动力学常数(k_obs)在反应温度为20℃时最高(1.756×10~(-2)s~(-1));H_2O_2的投加对于k_obs具有低促高抑的效果,在H_2O_2浓度为0.135 mmol·L-1时达到最优效果(k_obs,2.108×10~(-2)s~(-1)).p H的升高和阴离子HCO_3~-、SO_4~(2-)、Cl~-的投加会降低PD降解速率,而NO_3~-离子对PD的降解有明显地促进效果.对PD O_3降解过程的矿化效率和副产物分析可知,O_3氧化无法有效矿化PD,PD的O_3降解机理主要包括亲电加成和取代、吡唑环直链化、羟基化、脱苯基和脱甲基作用.     

新型纳米CeO2催化类Fenton降解盐酸四环素

本研究分别以NaOH和NH_3·H_2O为矿化剂,Ce(NO_3)_3·6H_2O为铈源,采用水热法成功制备两种新型纳米二氧化铈材料(CeO_2-Na与CeO_2-N).XRD、FESEM、Raman和EPR等表征手段以及非均相类Fenton降解盐酸四环素(TCH)性能分析结果表明,与CeO_2-N相比,纳米CeO_2-Na催化剂具有更大的比表面积和更高的表面氧空位浓度,其对TCH的催化性能也优于CeO_2-N.在TCH初始浓度为100 mg·L~(-1),催化剂投加量为0.7 g·L~(-1)和H_2O_2投加量为10 mmol·L~(-1)的条件下,CeO_2-Na/H_2O_2/TCH体系对TCH的去除率达86%,通过简单的热处理可以恢复催化剂的催化活性.TCH的降解机理研究表明,该非均相催化体系中起主要作用的是O~-_2·自由基.本研究为纳米氧化铈催化剂的制备及其非均相类Fenton的应用提供一定的技术和理论参考.     

CoFe_2O_4增强超声/H_2O_2降解环丙沙星

实验合成磁性CoFe_2O_4,采用X射线衍射仪(XRD)、扫描电镜(SEM)和X射线能谱仪(EDS)对其进行表征,研究其催化超声/H_2O_2(US/H_2O_2)降解环丙沙星的效果和机理.实验考察了CoFe_2O_4和H_2O_2添加浓度、初始p H值、不同形态氮、氯离子等因素对环丙沙星降解效果的影响.并以大肠杆菌为指示菌种,分析了CoFe_2O_4催化US/H_2O_2降解环丙沙星过程中抑菌性的变化.结果表明,CoFe_2O_4能够有效增强US/H_2O_2降解环丙沙星,CoFe_2O_4和H_2O_2浓度分别为0.04 g·L~(-1)和1.0 mmol·L~(-1)、p H=3.0、反应60 min环丙沙星的降解率达到85.26%;与NH_4~+相比,NO_3~-促进环丙沙星的降解,NO_2~-和Cl~-不同程度抑制环丙沙星的降解.自由基抑制结果表明,CoFe_2O_4增强US/H_2O_2降解环丙沙星主要在于·OH的生成.CoFe_2O_4稳定性结果表明,5次反复实验后,环丙沙星60 min的降解率仅降低了4%左右,催化剂的重复利用性较高.琼脂扩散实验表明,CoFe_2O_4在催化US/H_2O_2降解环丙沙星的同时,CoFe_2O_4/US/H_2O_2体系能够完全去除其对大肠杆菌的抑菌性.     

ZnFe/BC活化过硫酸盐降解金橙Ⅱ

为了研究ZnFe/BC在常温下活化过硫酸盐(PS)产生硫酸根自由基(SO_4~(·-))降解酸性偶氮染料金橙Ⅱ(AOⅡ)的效能,采用水热合成法制备了ZnFe/BC催化剂,并用X射线衍射(XRD)和扫描电子显微镜-能谱分析(SEM-EDS)对其形貌与负载成分进行了表征,结果显示生物炭上负载的球状颗粒物为ZnFe_2O_4和Fe_3O_4.考察了ZnFe/BC投加量、PS投加量、AOⅡ初始浓度以及初始pH对ZnFe/BC/PS体系降解AOⅡ效果的影响.结果显示,ZnFe/BC和PS投量的增加对AOⅡ的去除率均有提升效果,而随着AOⅡ初始浓度的增加,金橙Ⅱ的去除率逐渐降低,在初始pH值在3—10范围内,ZnFe/BC对PS均有较高的催化活性.ZnFe/BC催化剂投加量为0.5 g·L~(-1),PS投加量为5 mmol·L~(-1),溶液pH为初始值为6,反应90 min后,50 mg·L~(-1)金橙Ⅱ的脱色率可达到93.7%,而且其降解速率符合拟一级反应动力学.延长反应时间至180 min,TOC去除率达到39.7%.通过对催化剂ZnFe/BC稳定性研究,发现经4次连续循环使用后,金橙Ⅱ脱色率仍然可保持在85%以上,说明该催化剂具有良好的循环使用性能.通过投加对苯醌、乙醇和叔丁醇等3种不同种类的猝灭剂,证实了ZnFe/BC/PS体系中具有SO_4~(·-)、·OH和O_2~(·-)活性物种.发芽实验证明,在反应时间为180 min内,金橙Ⅱ降解出水对小麦发芽的抑制率随反应时间的进行而先升高而逐渐降低,最后基本无抑制.     

Sonocatalytic degradation of tetracycline antibiotic in aqueous solution by sonocatalysis

Tetracycline (TC), one of the most common antibiotics, is often poorly bio-degraded in conventional wastewater treatment plants. In this study, the sonocatalytic degradation of TC was investigated using TiO₂ nano-particles as catalyst. The effect of pH, initial TC concentrations, reaction times, and H₂O₂ concentrations were evaluated. The efficacy of ultrasonic irradiation alone in the removal of this pollutant was negligible but removal efficiency increased upon addition of TiO₂ up to 250 mg L^?1; increase of pH and initial TC concentration attenuated TC degradation. Addition of H₂O₂ raised the removal efficiency so that complete removal of TC was achieved within 75 min.     

H_2O_2致大鼠RTE细胞系氧化应激作用及GSH保护作用的体外研究

许多具有氧化作用的空气污染物,均能使细胞产生氧化损伤,使胸腺基质淋巴生成素(thymic stromal lymphopoietin,TSLP)含量上升。而TSLP是一种启动过敏性炎症的重要因子,会导致哮喘等疾病发生率的上升。在本研究中用过氧化氢(H_2O_2)模拟具有氧化作用的空气污染物进行染毒,研究细胞氧化应激水平的变化,并讨论还原型谷胱甘肽(GSH)对细胞受氧化损伤的保护作用。将大鼠支气管上皮细胞(RTE)分组培养,每组设置6个平行实验,分别用低、中、高剂量H_2O_2染毒3 h;高剂量设置1个重复,作为保护组,在染毒前用GSH保护2 h。结果显示,高剂量组H_2O_2(3.2 mmol·L~(~(-1)))染毒的细胞,其细胞活力下降(P0.01),丙二醛(MDA)水平上升(P0.01),TSLP水平上升(P0.05),与之相比,用GSH保护后的同剂量染毒组,上述指标得到全面缓解(P0.01)。这表明高浓度的H_2O_2会损伤细胞活力,并使MDA及TSLP水平上升,而GSH对TSLP及MDA的升高有极显著的抑制作用,即对细胞有一定的保护作用。     

Decolorisation of Acid Blue 74 by ultraviolet/H<Subscript>2</Subscript>O<Subscript>2</Subscript>

The photodegradation of Acid blue 74 in aqueous solution employing a H₂O₂/ultraviolet system in a photochemical reactor was investigated. The kinetics of decolorization were studied by application of a kinetic model. The results show that the reaction of decolorization followed pseudo-first order kinetics. We demonstrate that there is an optimum H₂O₂ concentration, at which the rate of the decolorization reaction is maximum. Irradiation at 253.7 nm of the dye solution in the presence of H₂O₂ results in complete discoloration after ten minutes of treatment.     

Photodegradation of an azo dye by silver-doped nano-particulate titanium dioxide

The synthesis of silver doped nano-particulate titanium dioxide (Ag/TiO₂) using a microemulsion method and an investigation of its photocatalytic activity for the degradation of Acid Red 27 in distilled water under UV-irradiation is reported. The prepared Ag/TiO₂ is characterized using transmission electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. The size of the Ag nanoparticles is around 5–15?nm, with almost uniform distribution on the TiO₂ particles. The efficiency of the photocatalytic process is evaluated to establish the optimum conditions, found to be at 2?wt% of Ag loading on TiO₂, catalyst dosage of 400?mg?L^?1, and calcination temperature of 300°C. Complete decolorization of the dye solution on Ag/TiO₂ was observed in 20?min of UV irradiation in the optimum conditions.     

HO ‐ initiated oxidation of acridine and aminacrine in aqueous media: Kinetic model

The photodecomposition of diluted aqueous solutions of acridine and aminacrine in the presence of hydrogen peroxide was studied. Irradiation was carried out with a low pressure mercury vapour lamp. The kinetic model describes the photodegradation rate of the organic compound with respect to the technological parameters of the reactor and provides the reaction rate constants of hydroxyl radicals towards these two molecules. This model was extented to high hydrogen peroxide concentrations ([H₂O₂] > 200 μmol/l) by considering the reactivity of hydroxyl radicals towards hydrogen peroxide. This assumption allows us to define an optimal hydrogen peroxide concentration.     

Hepatic effects of yttrium oxide nanoflowers: in vitro risk evaluation

Yttrium oxide nanoflowers were prepared by a hydrothermal technique, and X-ray diffraction and scanning electron microscopy were used to determine their structures. The cytotoxic and genotoxic potentials of aqueous dispersions of the nanoflowers to cultured primary rat hepatocytes were examined at concentrations up to 500 mg L^?1 for 72 h. Cell viability was determined by monitoring the reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, release of lactate dehydrogenase, and uptake of neutral red. Genotoxicity was assessed by the liver micronucleus assay. Exposure to Y₂O₃ nanoflowers at concentrations lower than 100 mg L^?1 did not lead to any cytotoxicity or genotoxicity. At higher concentrations (200, 400, and 500 mg L^?1), cell viability decreased and induction of micronuclei increased (400 and 500 mg L^?1).     

Hydrogen peroxide (H2O2) requirement for the oxidation of crude oil in contaminated soils by a modified Fenton's reagent

The oxidation of soil organic matter (SOM) and total petroleum hydrocarbon were investigated in two soils at eight different hydrogen peroxide (H₂O₂) concentrations to determine the optimal H₂O₂ dosage for the efficient remediation of soils contaminated by crude oil with minimal SOM removal. In our study, H₂O₂ concentrations up to 1100 mM increased the SOM destruction up to 10%–15% in the two soils while no improvement of the crude oil removal efficiencies was observed. The results indicate that the destruction of SOM significantly limits the oxidation of crude oil because SOM might consume H₂O₂ more effectively than crude oil at H₂O₂ concentrations above 1100 mM. In addition, H₂O₂ concentrations higher than 1100 mM were not expected for both soils because of the extremely rapid H₂O₂ decomposition, and low H₂O₂ utilization, of both soils.     

镉胁迫对脊尾白虾的毒性效应研究

为揭示重金属镉对脊尾白虾的毒性效应,采用急性毒性实验方法,研究了不同浓度镉(Cd~(2+))对脊尾白虾(Exopalaemon carinicauda)血清氧化应激相关生理指标的活性以及肌肉组织中腺苷酸转移酶基因(ANT)和热激蛋白70基因(HSC70)表达水平的影响。共设置4个Cd2+浓度胁迫(0、0.0002、0.001、0.005 mmol·L~(-1)),分别在0、3、6、9、12、24、36、48、72和96 h共10个时间点对相关指标进行测定。结果显示:不同浓度镉胁迫下,脊尾白虾血清中H_2O_2含量、MDA含量和GSH含量均表现为先升高后降低的趋势,H2O2含量在胁迫3 h时即出现明显的升高,而MDA和GSH则均在9 h时出现升高趋势,表现为一定的滞后性。H2O2含量在0.005 mmol·L~(-1)胁迫3 h时出现峰值,MDA含量在0.005 mmol·L~(-1)胁迫9 h时出现峰值,GSH含量在0.001mmol·L~(-1)胁迫48 h时出现峰值,且均与对照组存在显著性差异(P0.05)。HSC70基因的表达量在不同浓度胁迫下均表现为先升高后降低的趋势,且均在24 h时达到峰值,具体表达量水平的顺序为:0.0002 mmol·L~(-1)0.001 mmol·L~(-1)0.005 mmol·L~(-1)。ANT基因的表达量在不同浓度下则均表现为明显的下调趋势。由此可见,急性Cd~(2+)胁迫不仅影响脊尾白虾的氧化应激相关生理指标,还影响机体内组成型HSC70及与能量传递有关的ANT基因的表达水平。     

Nano-titanium dioxide (TiO2)-induced changes affecting Cu2+-mediated alterations in bacterium Bacillus subtilis and α-amylase

Titanium dioxide (TiO₂) nanoparticles possess the potential to coexist with Copper (Cu²⁺) in soil. The individual and combined toxicity of these two chemicals was evaluated using the bacterium Bacillus subtilis, a known soil model bacterium. Cu²⁺ (6.25–50?µg?mL^?1) alone produced toxicity to bacteria as evidenced by the decreased cell viability and deceased α-amylase production. The addition of TiO₂ (50?mg?mL^?1) enhanced the Cu²⁺-induced decrease in cell viability but elevated amylase activity. TiO₂ did not markedly affect the growth rate and lag period. A primary cause of TiO₂ increasing Cu²⁺ toxicity is presumed to be associated with hydroxyl radical formation, while increased amylase activity is considered to arise from Cu²⁺ facilitating TiO₂ degradation ability.     

Effect of silica additive on the thermal stability of catalysts for NOx abatement

The aim of the plesent investigation was to study the effect of SiO₂ addition on the thermal deactivation of V₂O₅/WO₃/TiO₂ catalysts used for NOx pollution abatement. The results suggest that the degradation of the catalytic properties is strongly correlated to the structural ageing which is, in turn, mainly related to the anatase–rutile phase transformation and to the WO₃ phase segregation. The addition of SiO₂ strongly influences the temperature at which these phenomena occur. In fact, it was found that the introduction of this oxide stabilizes the material, retarding the collapse of surface area, and increases the temperature of the anatase to rutile phase transition.