UV/O_3对亚硝基二甲胺降解产物的控制研究

对CUV/O3和UV/H2O2 2种高级氧化工艺降解水中亚硝基二甲胺(NDMA)和控制二甲胺(DMA)生成的能力进行了比较研究.结果表明,UV/H202能够有效降解NDMA,但不能控制NDMA降解产物DMA的生成;UV/O3高级氧化技术不仅能够有效地去除NDMA,同时对DMA的生成量也有很好的控制作用.进一步考察了不同臭氧浓度、溶液pH值以及NDMA初始浓度对UV/O3工艺控制DMA生成量的影响.结果表明,臭氧浓度对UV/O3控制DMA的生成有一定的影响,DMA的生成量随着臭氧浓度的增大而减小,臭氧浓度为6.64 mg·L-1时,降解7.7 mg·L-1 NDMA生成DMA的量为O.98 mg·L-1.溶液pH值对UV/03控制DMA的影响较大,酸性和中性pH条件下,DMA的生成量随着pH的增大略有增加;碱性pH条件下,DMA的生成量明显减小,pH;11.0时降解初始浓度为7.7 mg·L-1的NDMA,DMA的生成量仅为0.3 mg·L-1.NDMA的初始浓度对UV/03控制DMA的生成也有影响,NDMA初始浓度较小时,UV/O3对DMA生成的控制更为明显.     

UV Spectroscopic Monitoring of Vaporized Monoaromatic Hydrocarbons from Petroleum-Contaminated Soils

Fast and simple systems using ultraviolet (UV) absorbance were examined for on-line monitoring of monoaromatic hydrocarbons from petroleum-contaminated soils in this research. Since soil particles hinder the UV light transmittance, the absorbance measurement of vaporized monoaromatic hydrocarbons in soil gas extracted from petroleum-contaminated soils was proposed. In the fixed system that exhibited higher sensitivity than the portable one, the absorbance intensity of benzene, toluene, ethylbenzene, and xylene increased in proportion to the concentration of the contaminants. The portable system, however, was suitable for screening purpose, while it exhibited faster response. There was no interference from water, which helps the applicability of the proposed systems to the actual fields.     

Efficiency and degradation products elucidation of the photodegradation of mefenpyrdiethyl in water interface using TiO2 P-25 and Hombikat UV100

The photodegradation of mefenpyrdiethyl (MFD), an herbicide safener, was investigated in aqueous suspensions by using Degussa P-25 and Hombikat UV100 titanium oxide under simulated sunlight irradiation. The effects of initial concentration of the herbicide, pH, catalysts and hydrogen peroxide doses as well as their combinations were studied and optimized. Accordingly, the kinetic parameters were determined and the effectiveness of the processes was assessed by calculating the rate constants. A pseudo first-order kinetics was observed. Under experimental conditions, the degradation rate constants were strongly influenced using P-25 and no noticeable effect was observed for Hombikat UV100. DFT calculations with B3LYP/6-311+G(2d,p)//B3LYP/6-31+G(d,p) level of theory were performed to check whether significant conformational changes occur when the charge state of the MFD substrate changes and whether these changes could play a role in the dependency of photodegradation rate constant on the studied pH. High resolution mass spectrometry (FT-ICR/MS) was implemented to identify the main degradation products.     

有机硅改性环氧树脂的光固化动力学与性能研究

目的研究紫外光固化有机硅改性环氧树脂的固化行为和性能。方法通过介电分析(DEA)研究光引发剂、热引发剂及有机硅含量对紫外光固化脂环族环氧树脂反应过程的影响,利用热重(TG)、差示扫描热(DSC)和显微硬度仪对有机硅树脂改性环氧树脂性能进行分析。结果发现光引发剂与热引发剂对固化效率可起到协同互补的作用,增加光引发剂和热引发剂的浓度,可缩短引发时间,加快固化速率,提高固化效率。与纯环氧树脂相比,有机硅改性环氧树脂的固化效率和初始分解温度都有所下降,但高温阶段降解速率明显降低,500℃的残炭率也得到提高。当加入质量分数为10%的有机硅时,固化物表现出较好的耐热性能,树脂维氏硬度可达31.75HV。结论紫外光可以很好地固化有机硅改性环氧树脂。     

UV254nm+185nm光照降解气态甲苯的实验研究

研究了波长为254nm+185nm紫外光照射下,甲苯初始浓度、停留时间、相对湿度、O2浓度等因素对甲苯光降解效率的影响.通过定量UV254nm+185nm光照下体系中O3的产生浓度变化,以及降解过程中中间产物苯和苯甲醛的变化趋势,讨论了甲苯在UV254nm+185nm照射下降解机理.结果表明,甲苯去除率随着O2含量、停留时间的增加而升高;随着初始浓度的增加而降低.与湿度的关系为先急剧升高然后缓慢增加,而后降低,最佳相对湿度在40%~50%.当甲苯初始浓度为16.1mg/m3,O2含量为20%,相对湿度为40%时,体系对甲苯的降解效率为82.2%,降解速率为0.44mg/(m3·s),产生的O3浓度为131.13mg/m3,中间产物苯和苯甲醛的浓度分别为0.086,0.135mg/m3.在反应体系中,甲苯可吸收185nm波长紫外光直接降解,但主要被体系中产生的自由基氧化降解.     

Enhancement of UV and chromate mutagenesis by nickel ions in the Chinese hamster HGPRT Assay †

1. The HGPRT (Hypoxanthine‐Guanine‐Phospho‐Ribosyl‐Transferase) assay with Chinese Hamster V79 cells was used to measure the mutagenic effects of UV irradiation, potassium dichromate and nickel chloride. The agents were tested separately and in the combinations of UV plus nickel and dichromate plus nickel.

2. UV, Cr(VI) and Ni(II) were confirmed to be mutagenic in the V79 cell assay. The combination of UV(5J/m²) and Ni(II) (0.5 mM) caused a mutation rate 11.2 times above that corresponding to the sum of the individual mutation rates of these agents. The combined action of Cr(VI) (0.1 mM) and Ni(II) (0.5 mM) produced a mutation rate 2.8 fold above that corresponding to the sum of the individual rates of the separate agents.

3. The enhancing effect of nickel chloride on the mutagenicity of UV or Cr(VI) is interpreted by an interference of Ni(II) with the repair of DNA lesions.     

紫外辐射下的生物降解及微生物群落的变化

分别采用一体式循环床紫外光/生物膜反应器（PCBBR）和气升式内循环的紫外光/生物膜反应器（ILPBR）,用于苯酚、2,4,6-三氯酚（TCP）和抗生素药物磺胺甲恶唑（SMX）的降解.结果表明,苯酚、TCP和SMX在紫外光解与生物降解的共同作用下,其去除速率分别达到0.65、0.11和0.17 mg.（L.min）–1...     

阴阳极成对耦合紫外光辅助电催化降解毒死蜱

以空气扩散阴极、纯铂阳极和紫外灯构建了阴阳极成对耦合紫外光辅助电催化的体系,并系统地研究了电流密度、阳极SO42-浓度以及毒死蜱初始浓度对毒死蜱降解效果的影响.结果表明,当阴极/阳极的电流密度为45/450 mA·cm-2,阳极SO42-浓度为1.0 mol-L-1,毒死蜱初始浓度为25 mg·L-1时,反应60 mi...     

Estimation of Similarity in the Qualitative Composition of Humic Substance in Marine Sediments By Means of an Uv-Spectroscopic Library

In this paper a method for the study of the qualitative similarity of extractable humic substance (EHS) in marine sediments based on the realisation of UV spectral library of EHS is described. the spectral library was built including the digitised spectra of humic substance extracted from several marine sediments (46 samples) and two samples of standard materials (lignin sulphonate and humic substance) in a Statistica data file. the data matrix was elaborated by means of different multivariate statistic techniques such as Cluster Analysis (CA), Principal Components Analysis (PCA) and the univariate technique Spectral Correlation Analysis (SCA). This approach allows us to show the contribution of different organic compounds (aromatic, lipid and acid) to the composition of EHS and moreover it evidences also the structural characteristics of EHS in terms of similarities in the qualitative composition of samples such as presence of terrestrial and/or vegetal contributions. the UV library is an objective tool to study the qualitative composition of EHS and it represents a complementary approach to the most common methods based on the application of spectroscopic (IR, ¹³CNMR), potentiometric and chromatographic techniques.     

Electrochemical degradation of Acid Red I dye and its treatment by UV light

Degradation of Acid Red I (ARI) dye by electrochemical treatment and UV light irradiation was studied in this work. The effect of the current density and the concentration of NaCl and dye on the decoloration and degradation efficiency were studied and optimized. The UV irradiation was monitored by UV-Vis spectrophotometry and chemical oxygen demand. The kinetic constants for decoloration and degradation were calculated. Degradation of 86% was achieved in 160?min and the first-order kinetic constant was 0.013?min^?1. Degradation products were identified by gas chromatography/mass spectrometry. The mechanism for the degradation of ARI was proposed.