Fe2+/UV催化臭氧-曝气生物滤池降解腈纶废水研究

腈纶废水是一种难降解的有毒有机废水。本文采用Fe2+/UV催化臭氧-曝气生物滤池降解腈纶废水,探讨了臭氧浓度和紫外光辐射强度等影响因素对腈纶废水的COD去除效果的影响,并考察了紫外催化臭氧氧化单元和曝气生物滤池单元对COD去除的协同作用。结果表明,臭氧浓度对COD的去除率影响较大,臭氧浓度下降25%时,臭氧催化氧化和曝气生物滤池单元处理的COD去除率分别下降了12.53%和15.98%。紫外光强度对臭氧催化氧化单元的COD去除率影响较小,但对曝气生物滤池单元影响较大。臭氧催化氧化单元和曝气生物滤池单元COD去除率之比为1∶2,其协同作用使总出水COD值稳定在较低水平。     

负载型贵金属纳米粒子作为光/超声催化剂在化学合成和降解污染物方面的应用

综述了Au/TiO2、Au/ZrO2、Ag/AgCl等负载型贵金属纳米粒子作为有效的光/超声催化剂在化学合成和降解污染物方面的应用.负载型贵金属纳米粒子能够有效地将太阳能转化为化学能.在紫外光或可见光的辐照下,负载型贵金属纳米粒子能够催化一系列的选择性化学转化,如醇类化合物氧化为醛/酮类化合物、硫醇氧化为二硫化合物、苯氧化为苯酚、硝基苯类化合物还原为偶氮化合物等.在超声波辐射下,负载型贵金属纳米粒子能够有效地催化分解水产氢.此外,在紫外光或可见光的辐照下,负载型贵金属纳米粒子能够有效地催化降解多种污染物,如醛类、醇类、酸类、酚类化合物和染料等.在超声波辐射下,负载型贵金属纳米粒子也能够有效地催化降解包括染料在内的有机污染物.     

超氧化物歧化酶模型化合物的合成, 表征和活性测定

合成了二(2-苯并咪唑亚甲基)胺(N3)及其四种全新的过渡金属的双核配合物。通过元素分析、红外光谱和紫外光谱对配体及配合物进行了结构表征,利用邻苯三酚自氧化法测定了四种模拟化合物催化超氧阴离子自由基歧化反应的活性。     

六钨酸四丁基铵盐和异丙醇体系的催化氧化反应的ESR研究Ⅰ.

本文研究了六钨酸四丁基铵盐在紫外光辐照的条件下催化氧化异丙醇为丙酮的反应。采用自旋捕捉技术与电子自旋共振相结合的方法,在位检测到氧化反应过程中有活泼自由基中间体产生,并观察到光电流产生。文中对六钨酸四丁基铵盐的催化反应机理进行了讨论。     

催化荧光光度法测定痕量亚硝酸根

亚硝酸根广泛存在于环境、水体、食品等物质中,它可与胺类及酰胺类化合物反应生成致癌物亚硝胺,因此,它是水质、环境、食品等检测的重要项目之一。催化动力学光度法测定亚硝酸根已有不少报道,而催化荧光法测定亚硝酸根的报道不多。吡啰红B是一种生物染色剂,在水溶液中发射红色荧光。试验发现,稀磷酸介质中,溴酸钾氧化吡哕比B使荧光猝灭,亚硝酸根对此氧化还原褪色反应具有灵敏催化作用,据此建立了测定亚硝酸根的催化荧光光度法。本法灵敏度较高,选择性好,简便快速,用于水及蔬菜中痕量亚硝酸根的测定,结果满意。     

六钨酸四丁基铵盐和异丙醇体系的催化氧化反应的ESR研究Ⅰ.

本文研究了六钨酸四丁基铵盐在紫外光辐照的条件下催化氧化异丙醇为丙酮的反应。采用自旋捕捉技术与电子自旋共振相结合的方法,在位检测到氧化反应过程中有活泼自由基中间体产生,并观察到光电流产生。文中对六钨酸四丁基铵盐的催化反应机理进行了讨论。     

催化荧光光度法测定痕量亚硝酸根

1　引　　言亚硝酸根广泛存在于环境、水体、食品等物质中 ,它可与胺类及酰胺类化合物反应生成致癌物亚硝胺 ,因此 ,它是水质、环境、食品等检测的重要项目之一。催化动力学光度法测定亚硝酸根已有不少报道 ,而催化荧光法测定亚硝酸根的报道不多。吡红Ｂ是一种生物染色剂 ,在水溶液中发射红色荧光。作者发现 ,稀磷酸介质中 ,溴酸钾氧化吡红Ｂ使荧光猝灭 ,亚硝酸根对此氧化还原褪色反应具有灵敏催化作用 ,据此建立了测定亚硝酸根的催化荧光光度新方法。该法灵敏度较高 ,选择性好 ,简便快速 ,用于水及蔬菜中痕量亚硝酸根的测定 ,结果满意…     

硅胶固载聚4-乙烯吡啶-Cu(Ⅱ)配合物催化分子氧氧化乙苯的性能研究

以固载于微米级硅胶表面的聚4-乙烯吡啶-铜(Ⅱ)配合物(P4VP-Cu(Ⅱ)/SiO2)为催化剂,以分子氧为氧化剂,在常压下实施了将乙苯氧化为苯乙酮的催化氧化反应;用红外光谱、紫外光谱及液相色谱对产物的化学结构进行了表征;重点研究了催化剂的催化性能,以及各种条件(温度、催化剂性质、催化剂用量等)对催化氧化反应的影响;并分析了催化氧化反应的机理.研究结果表明,固载于硅胶表面的聚4-乙烯吡啶-Cu(Ⅱ)配合物能有效地活化分子氧,显著地催化氧化乙苯为苯乙酮的反应过程;该催化剂具有优良的催化活性与选择性,于130℃常压下通氧气反应10h,可使约60%的乙苯转化为苯乙酮,另一氧化产物α-甲基苄醇的含量则极少.另外,该催化剂具有较好的重复使用稳定性.     

难降解有机废水的催化氧化法处理

催化氧化法可通过多种途径来加强传统的化学法处理效果，目前已成为难降解有机废水处理的一项重要新技术。本文介绍了光催化氧化法、均相氧化法、多相氧化法(包括电催化氧化法)以及超临界水氧化技术的国内外研究现状及特点，并对其在有机废水中的应用情况和发展前景作了扼要评述。     

光化学反应在分析化学中应用的研究利用光敏化氧化作用测定铁

利用甲基橙光化学动力学法测定合金及环境样品中的铁,国内外文献已有报道。本文研究了用铁(Ⅲ)对光敏化蒽醌(AQ)氧化邻氨基酚(OAφ)的催化作用来测定实际样品中的铁。在紫外光照射下,敏化了的AQ能氧化OAφ,很多金属离子如Fe(Ⅲ),Cr(Ⅲ),Ni(Ⅱ)、Mn(Ⅱ)、V(Ⅴ)、MO(Ⅵ),Cu(Ⅱ)、CO(Ⅱ)等能催化该反应。苏联Щаээо等人已经建立了钼的测定方法。本文探讨了铁(Ⅲ)催化光敏化AQ氧化OAφ测定铁的可能性。实验结果表明,光敏化     

Developments in electrode materials for wastewater treatment

This review provides a current opinion about the most recent advances in the development of novel materials (i.e., anodes and cathodes), as well as new synthesis methodologies, which have been used in water and wastewater treatment by electrochemically driven oxidation technologies. The first section focuses on the advances to produce novel anodic materials comprising the active anodes — which play a key role in direct and indirect oxidation and the nonactive materials — which attract attention due to their high capacity to generate hydroxyl radicals. The second section describes recent progress on the novel emerging cathodic materials that are directly related to in situ electrogeneration of oxidants and are commonly applied in the electro-Fenton technology. Finally, the perspectives and prospects of these novel electrode materials for environmental applications are given.     

Indirect electrochemical oxidation of reverse osmosis membrane concentrates at boron-doped diamond electrodes

The treatment or disposal of concentrates generated from the filtrative treatment of water is rapidly becoming a factor of major environmental concern. This preliminary study discusses a novel approach in the abatement of reverse osmosis membrane retentate i.e. electrochemical oxidation. The recalcitrant organic constituents as well as the ammonia nitrogen in the retentate could be readily oxidised using boron-doped diamond electrodes. From the model fitted to these data, a constant removal rate and current efficiency was calculated. Analysis of the inorganic chlorinated species revealed that the oxidation mechanism was mainly due to the indirect oxidative action of electrogenerated hypochlorite.     

毛细管电泳用于形态分析

一种元素的生物可给性、环境行为和迁移性在很大程度上取决于它的形态。如不同的键合形式或氧化态，因此，作为元素物种鉴别和含量测定的形态分析变得越来越重要。毛细管电泳作为一种分离分析技术有许多优点可以满足形态分析的要求。本文从样品的预处理、毛细管电泳的修饰、进样方式、分离模式和检测等几个方面评述了毛细管电泳在形态分析中的应用。     

Detection of total microcystin in fish tissues based on lemieux oxidation and recovery of 2-methyl-3-methoxy-4-phenylbutanoic acid (MMPB) by solid-phase microextraction gas chromatography-mass spectrometry (SPME-GC/MS)

Microcystins (MCs) are widespread cyanobacterial toxins in freshwater systems, and have been linked to both acute and chronic health effects. A growing number of studies suggest that MC can bioaccumulate in food webs. Although, several methods (i.e. ELISA, LC-MS) have been developed for analysis of MC in water, extraction (for subsequent analysis) of the toxin from biological matrices (i.e. animal tissues) is impeded owing to covalent binding of toxins and active sites of their cellular targets, i.e. protein phosphatases. As an alternative approach, chromatographic methods for analysis of a unique marker, 2-methyl-3-methoxy-4-phenylbutanoic acid (MMPB), the product of the Lemieux oxidation of MCs, have been previously developed, and shown to measure total (bound and unbound) MC. Application, however, has been limited by poor recovery of the analyte. An improved recovery method is proposed – specifically the use of solid-phase microextraction (SPME). The MMPB analogue, 4-phenylbutanoic acid (4PB), and oxidized MC, were used to develop methods, and we specifically investigated several SPME fibres, and post-oxidation steps. Specifically, a method employing post-oxidation methyl esterification, followed by headspace SPME recovery of MMPB, was developed, and subsequently applied to analysis of environmental samples (i.e. fish tissues) previously shown to contain MCs. The method shows high linearity for both water and tissues spiked with MC, and an improved limit of quantitation of approximately 140?ng?g^?1. Evaluation of field samples by SPME-GC/MS detected considerably higher levels of MC, than detected by conventional methods (i.e. ELISA), and it is proposed that this technique reveals MC (particularly in the bound form) that is not detected by these methods. These results indicate that the developed method provides improved detection capability for MC in biological matrices, and will enhance our ability to understand bioaccumulation in freshwater food webs, as well as monitor exposure.     

New In-situ Sampling and Analysis of the Production of CeO<Subscript>2</Subscript> Powders from Liquid Precursors using a Novel Wet Collection System in a rf Inductively Coupled Thermal Plasma Reactor. Part 1: Reactor System and Sampling Probe

A new reactor and a novel in-situ sampling technique were developed for the study of the synthesis of CeO₂ powders produced from dissolved cerium nitrate salts. The conical reactor minimized particle recirculation and provided a highly symmetrical and undisturbed plasma flow suitable for the analysis of the phenomena affecting the formation of CeO₂ powders. Both a calorimetric study of the reactor and a thermodynamic analysis of CeO₂ formation were conducted. The sampling probe is described and near-isokinetic sampling was achieved. The sampled particles were collected using a miniature wet collection system, i.e. a mist atomizer and a custom-made spray chamber. A numerical simulation of the velocity and temperature fields of the plasma gas in the reactor was done using Fluent. A comprehensive droplet-to-particle formation mechanism presented elsewhere is revisited and expanded based on calorimetry, thermodynamics of CeO₂ formation, numerical simulations and collected particles. No traces of other oxidation states other than CeO₂ were found.     

Solid-phase microextraction in biomedical analysis

Chromatographic methods are preferred in the analysis of organic molecules with lower molecular mass (<500 g/mol) in body fluids, i.e., the assay of drugs, metabolites, endogenous substances and poisons as well as of environmental exposure by gas chromatography (GC) and liquid chromatography (LC), for example. Sample preparation in biomedical analysis is mainly performed by liquid-liquid extraction and solid-phase extraction. However, new methods are investigated with the aim to increase the sample throughput and to improve the quality of analytical methods. Solid-phase microextraction (SPME) was introduced about a decade ago and it was mainly applied to environmental and food analysis. All steps of sample preparation, i.e., extraction, concentration, derivatization and transfer to the chromatograph, are integrated in one step and in one device. This is accomplished by the intelligent combination of an immobilized extraction solvent (a polymer) with a special geometry (a fiber within a syringe). It was a challenge to test this novel principle in biomedical analysis. Thus, an introduction is provided to the theory of SPME in the present paper. A critical review of the first applications to biomedical analyses is presented in the main paragraph. The optimization of SPME as well as advantages and disadvantages are discussed. It is concluded that, because of some unique characteristics, SPME can be introduced with benefit into several areas of biomedical analysis. In particular, the application of headspace SPME-GC-MS in forensic toxicology and environmental medicine appears to be promising. However, it seems that SPME will not become a universal method. Thus, on-line SPE-LC coupling with column-switching technique may be a good alternative if an analytical problem cannot be sufficiently dealt with by SPME.     

Heterogeneous oxidation of the insecticide cypermethrin as thin film and airborne particles by hydroxyl radicals and ozone

Evaluation of pesticides' fate in the atmosphere is important in terms of environmental effects on non-target areas and risk assessments analysis. This evaluation is usually done in the laboratory using analytical grade materials and is then extrapolated to more realistic conditions. To assess the effect of the pesticide purity level (i.e. analytical vs. technical) and state (i.e. sorbed film vs. airborne particles), we have investigated the oxidation rates and products of technical grade cypermethrin as thin film and in its airborne form, and compared it with our former results for analytical grade material. Technical grade thin film kinetics for both ozone and OH radicals revealed reaction rates similar to the analytical material, implying that for these processes, the analytical grade can be used as a good proxy. Oxidation products, however, were slightly different with two additional condensed phase products: formanilide, N-phenyl and 2-biphenyl carboxylic acid, which were seen with the technical grade material only. OH experiments revealed spectral changes that suggest the immediate formation of surface products containing OH functionalities. For the ozonolysis studies of airborne material, a novel set-up was used, which included a long-path FTIR cell in conjugation with a Scanning Mobility Particle Sizer (SMPS) system. This set-up allowed monitoring of real-time reaction kinetics and product formation (gas and condensed phases) together with aerosol size distribution measurements. Similar condensed phase products were observed for airborne and thin film technical grade cypermethrin after ozonolysis. Additionally, CO, CO(2) and possibly acetaldehyde were identified as gaseous oxidation products in the aerosols experiments only. A kinetic model fitted to our experimental system enabled the identification of both primary and secondary products as well as extraction of a formation rate constant. Kinetic calculations (based on gaseous products formation rate) have revealed values similar to that of the thin film experiments. Interestingly, heterogeneous oxidation of cypermethrin was also found to generate ultra fine secondary organic aerosols. Again, no significant difference was observed between analytical and technical grade materials. However, particle size distribution was much broader when films were exposed to OH and ozone than to ozone alone.     

Serial ligand catalysis: a highly selective allylic C-H oxidation

We are reporting a mild, chemo-, and highly regioselective Pd(II)-catalyzed allylic oxidation of alpha-olefins to furnish branched allylic esters that proceeds via a novel serial ligand catalysis mechanism in which two different ligands (i.e., vinyl sulfoxide 2 and BQ) interact sequentially with the metal to promote distinct steps of the catalytic cycle (i.e., C-H cleavage and pi-allyl functionalization, respectively).     

Analysis of the oxidation process of powders and sinters of the austenitic stainless steel

Nowadays, austenitic stainless steels due to its properties are widely used in various applications. In powder metallurgy technology, one of the key factors, affecting the pressing process, the sintering phenomena and the final properties of sintered parts, is the shape and particle size of the powders. The article presents the results focused on analysis of the oxidation process of austenitic stainless steel. Powders of the same chemical composition, however of different shapes, depending on the manufacturing technique, i.e. spherical after inert gas atomization and sponge after water atomization, were investigated. Moreover, the influence of particles’ size from different ranges 40–56 and 80–100 µm on the oxidation behaviour was analysed. Thermal measurements, differential scanning calorimetry and thermogravimetry, were performed by the STA 409 CD (Netzsch) advanced coupling techniques. Moreover, dilatometry technique has been used for the analysis of the influence of the size and shape of particles on the sintering process. Sinters oxidation phenomena have also been determined. Based on the obtained results, it was found that both shape and size of powders have a significant influence on the oxidation processes of powders as well as sinters of the austenitic stainless steel.     

Charge transfer events in semiconducting single-wall carbon nanotubes

Electron-donating ferrocene units have been attached to SWNTs, with different degrees of functionalization. By means of a complementary series of novel spectroscopic techniques (i.e., steady-state and time-resolved), we have documented that mutual interactions between semiconducting SWNT and the covalently attached electron donor (i.e., ferrocene) lead, in the event of photoexcitation, to the formation of radical ion pairs. In the accordingly formed radical ion pairs, oxidation of ferrocene and reduction of SWNT were confirmed by spectroelectrochemistry. It is, however, shown that only a few semiconducting SWNTs [i.e., (9,4), (8,6), (8,7), and (9,7)] are susceptible to photoinduced electron transfer processes. These results are of relevant importance for the development of SWNT-based photovoltaics.