氧化亚铜和氢氧化铜对苦草抗氧化酶活性和叶绿素含量的影响

研究了不同浓度氧化亚铜和氢氧化铜可湿性粉剂染毒对苦草叶片抗氧化酶〔超氧化物歧化酶(SOD)、抗坏血酸过氧化物酶(APX)和过氧化物酶(POD)〕比活力、丙二醛(MDA)含量和叶绿素含量的影响。结果表明,以0.15～1.5 mg.L-1氧化亚铜可湿性粉剂对苦草染毒7 d,其叶片SOD、APX和POD活性明显升高,1.5 mg.L-1处理组3种抗氧化酶比活力分别比助剂对照组升高49.0%、77.0%和39.0%,MDA含量极显著上升46.9%,总叶绿素含量显著下降42.6%。染毒14 d后3种抗氧化酶比活力均有不同程度回落,MDA含量恢复至正常水平,总叶绿素含量也有所回升。以0.1～1.0 mg.L-1氢氧化铜对苦草染毒7 d,1.0 mg.L-1处理组3种抗氧化酶比活力和MDA含量也呈显著上升趋势,总叶绿素含量显著下降。染毒14 d时3种抗氧化酶比活力和MDA含量恢复到正常水平,总叶绿素含量回升。上述结果显示,在氧化亚铜和氢氧化铜引起的铜胁迫早期,苦草叶片抗氧化酶因过氧化应激响应而上升,膜脂出现一定程度过氧化损伤,叶绿素含量下降,但随着暴露时间的延长,苦草对铜胁迫产生适应性,过氧化损伤得以缓解,叶绿素含量回升。     

Fe(VI)/Fenton联合体系氧化降解菲的路径及机理

Fe（VI）/Fenton联合体系降解多环芳烃的效果良好,但其机理及降解路径仍需进一步被探究.采用荧光及GC-MS技术,考察弱酸条件下Fe（VI）降解菲的效果,并对比中性及碱性条件研究其氧化机理,进而分析Fe（VI）/Fenton联合体系对菲的作用机理及菲的降解路径.结果表明,弱酸条件下Fe（VI）氧化菲时,·OH参与反应较少,起氧化作用的可能为中间高价态铁.在该条件下,Fe（VI）对菲的降解效果稍差于中性及碱性,但此时Fe（VI）的高氧化性能可提高菲的矿化效果.联合氧化体系中,菲逐步被氧化、羟基化、脱碳、加氢而最终转化为CO₂和H₂O,主要的中间产物为邻苯二甲酸酯衍生物和9-芴甲醛衍生物.联合氧化体系可合理利用Fe（VI）氧化过程中产生的Fe（II）,并发挥高价态铁与·OH在氧化性能上的优势,实现对菲及产物的降解与矿化.     

Removal of hexavalent chromium from contaminated waters by ultrasound-assisted aqueous solution ball milling

Batch mode experiments were conducted to study the removal of hexavalent chromium(Cr(Ⅵ)) from aqueous solutions using ultrasound-assisted aqueous solution ball milling.The results show that the reduction rate of Cr(Ⅵ) by ultrasound-assisted aqueous solution ball milling was significantly faster than that by ball milling or ultrasound treatment alone,and an initial Cr(Ⅵ) concentration of 166 mg/L could be decreased to 0.35 mg/L at 120 min.The decisive factors, including initial concentration of Cr(Ⅵ), p H value, ultrasonic frequency and filling gas, were studied. It was found that the optimal ultrasonic frequency for ultrasound-assisted aqueous solution ball milling device was 20 k Hz, and the rate of Cr(Ⅵ)reduction as a function of filling gas followed the order: Ar air N_2 O_2. Samples were characterized by X-ray diffraction, fluorescence measurements, atomic absorption and the diphenylcarbazide colorimetric method. The Cr(Ⅵ) transformed into a precipitate that could be removed from the contaminated water, after which the water could be reused.     

可控合成La（OH）3纳米球光催化去除NO及其催化性能机制研究

以KOH和La(NO3)3·6H2O为前驱体,柠檬酸为保护剂,采用一步水热法合成三维La(OH)3纳米球光催化剂.通过XRD、SEM、PL和UV-vis DRS等对样品进行结构表征.结果表明,柠檬酸的加入量对La(OH)3的形貌均匀性和催化活性均有较大影响.柠檬酸和La(NO3)3·6H2O的物质的量的比为2∶1时,得到的样品为形貌均匀的纳米球,光催化活性最佳且稳定性好.这是因为三维的纳米球结构更容易促进光生载流子的分离;此外,形貌均匀无团聚,增加了催化剂表面的活性位点,使反应过程中反应物和中间产物迅速扩散,从而光催化活性最高.在光催化过程中,羟基自由基(·OH)和超氧自由基(·O-2)是最主要的氧化物种.NO可以和产生的·OH和·O-2反应生成HNO2和HNO3,从而去除NO.本文研究结果充实了La(OH)3光催化材料的合成基础理论,探讨了La(OH)3光催化活性机理,为La(OH)3应用打开了新的视野.     

Intrinsic chemiluminescence production from the degradation of haloaromatic pollutants during environmentally-friendly advanced oxidation processes: Mechanism, structure–activity relationship and potential applications

The ubiquitous distribution of halogenated aromatic compounds(XAr) coupled with their carcinogenicity has raised public concerns on their potential risks to both human health and the ecosystem. Recently, advanced oxidation processes(AOPs) have been considered as an"environmentally-friendly" technology for the remediation and destruction of such recalcitrant and highly toxic XAr. During our study on the mechanism of metal-independent production of hydroxyl radicals(UOH) by halogenated quinones and H_2O_2, we found, unexpectedly, that an unprecedented UOH-dependent two-step intrinsic chemiluminescene(CL) can be produced by H_2O_2 and tetrachloro-p-benzoquinone, the major carcinogenic metabolite of the widely used wood preservative pentachlorophenol. Further investigations showed that, in all UOH-generating systems, CL can also be produced not only by pentachlorophenol and all other halogenated phenols, but also by all XAr tested. A systematic structure–activity relationship study for all 19 chlorophenolic congeners showed that the CL increased with an increasing number of Cl-substitution in general. More importantly, a relatively good correlation was observed between the formation of quinoid/semiquinone radical intermediates and CL generation. Based on these results, we propose that UOH-dependent formation of quinoid intermediates and electronically excited carbonyl species is responsible for this unusual CL production; and a rapid, sensitive,simple, and effective CL method was developed not only to detect and quantify trace amount of XAr, but also to provide useful information for predicting the toxicity or monitoring real-time degradation kinetics of XAr. These findings may have broad chemical, environmental and biological implications for future studies on halogenated aromatic persistent organic pollutants.     

微生物菌粉与菌液矿化固结Zn~(2+)的研究与对比

利用碳酸盐矿化菌在底物诱导下的酶化作用,分解产生碳酸根离子,矿化固结环境(土壤水体)当中的游离重金属离子,减少其危险。文章以Zn2+溶液模拟重金属离子污染体系,研究过程中发现,生产的矿化产物主要是ZnO.5(OH)62(CO)3。分别用菌粉和菌液进行微生物矿化试验,对矿化产物进行底物分解率,SEM,XRD,矿化粒径的对比研究。从对比研究结果看,菌粉复活后,可以达到与菌液基本相同的矿化效果。而菌粉相对于菌液而言,其主要优势在于能长时间储存,产品体积小,运输起来更方便,因此,菌粉具有更广泛的应用性。     

Reaction mechanism of dicofol removal by cellulase

It remains unclear whether dicofol should be defined as a persistent organic pollutant. Its environmental persistence has gained attention. This study focused on its degradation by cellulase. Cellulase was separated using a gel chromatogram, and its degradation activity towards dicofol involved its endoglucanase activity. By analyzing the kinetic parameters of cellulase reacting with mixed substrates, it was shown that cellulase reacted on dicofol and carboxyl methyl cellulose through two different active centers. Thus, the degradation of dicofol was shown to be an oxidative process by cellulase. Next, by comparing the impacts of tert-butyl alcohol (a typical OH free-radical inhibitor) on the removal efficiencies of dicofol under both cellulase and Fenton reagent systems, it was shown that the removal of dicofol was initiated by OH free radicals produced by cellulase. Finally, 4,4′-dichloro-dibenzophenone and chloride were detected using gas chromatography mass spectrometry and ion chromatography analysis, which supported our hypothesis. The reaction mechanism was analyzed and involved an attack by OH free radicals at the orthocarbon of dicofol, resulting in the degradation product 4,4′-dichloro-dibenzophenone.     

真空紫外光降解瓦斯反应动力学规律

为了研究真空紫外光降解瓦斯过程的反应动力学规律,在自制的真空石英光化学反应器中以含甲烷标准气体模拟矿井瓦斯,运用Langmuir-Hinshelwood(L-H)拟一级反应动力学模型对不同光照强度、氧气体积分数、甲烷初始体积分数和水分子体积分数下瓦斯(甲烷)的降解过程进行拟合.结果表明:真空紫外光降解瓦斯反应动力学规律符合一级反应动力学特性;光照强度、甲烷初始体积分数、氧气体积分数和水分子体积分数是影响真空紫外光降解瓦斯的主要因素;瓦斯(甲烷)降解的反应速率随光照强度和氧气体积分数增大而增大,随甲烷初始体积分数增大而减小,随水分子体积分数增大而先增大后减小.     

Luminescence in the oxidation of isoproterenol by the superoxide anion radical in dimethyl sulfoxide

Chemiluminescence appearing during oxidation of isoproterenol using chemical system involving superoxide anion radical has been studied. Chemiluminescence and fluorescence spectra were measured. The chemiluminescence spectrum was measured with cut‐off filters and revealed bands with maximum at 440, 480, 550, 640 and 700 nm. The bands at 480, 640 and 700 nm were similar to those observed for singlet oxygen. The fluorescence spectrum exhibited maximum at 560 nm.

The inhibitory effect of several biologically important compounds known as O₂ ^?‐ HO^? and ¹O₂ scavengers on the light emission was studied.

The obtained results indicate that oxidation of isoproterenol by O₂ ^?‐ involves products in the electronically excited states. The data also seem to indicate the protective effect of isoproterenol on the deoxyribose degradation.     

Do aerosols act as catalysts in the OH radical initiated atmospheric oxidation of volatile organic compounds?

Smog chamber/FTIR techniques were used to study the relative reactivity of OH radicals with methanol, ethanol, phenol, C₂H₄, C₂H₂, and p-xylene in 750 Torr of air diluent at 296±2 K. Experiments were performed with, and without, 500–8000 μg m⁻³ (4000–50 000 μm² cm⁻³ surface area per volume) of NaCl, (NH₄)₂SO₄ or NH₄NO₃ aerosol. In contrast to the recent findings of Oh and Andino (Atmospheric Environment 34 (2000) 2901, 36 (2002) 149; International Journal of Chemical Kinetics 33 (2001) 422) there was no discernable effect of aerosol on the rate of loss of the organic compounds via reaction with OH radicals. Gas kinetic theory arguments cast doubt upon the findings of Oh and Andino. The available data suggest that the answer to the title question is “No”. As part of this work the rate constants for reactions of OH radicals with methanol, ethanol, and phenol in 750 Torr of air at 296 K were determined to be: k_OH+CH3OH=(8.12±0.54)×10⁻¹³, k_OH+C2H5OH=(3.47±0.32)×10⁻¹² and k_OH+phenol=(3.27±0.31)×10⁻¹¹ cm³ molecule⁻¹ s⁻¹.