高效液相色谱-串联质谱法研究氯对水中藻毒素MC-LR的降解作用

选择目前最常用的预氧化剂———氯作为研究对象,利用液相色谱-串联质谱的检测手段,展开了有效氯对MC-LR降解作用的研究。结果表明,HPLC-MS方法可靠、灵敏度高,在5~500μg.L-1范围内,MC-LR浓度与HPLC-MS峰面积呈线性关系,相关系数r为0.999 3;在常规的氧化剂投加量和反应时间条件下,有效氯对MC-LR表现出良好的降解作用,降解反应符合一级动力学模式;通过对质谱图的分析,确定了降解产物的相对分子质量,由此进一步探讨了MC-LR的氯化降解机理。     

Rapid Determination of HAAs Formation Potential of the Reaction of Humic Acid with Chlorine or Chlorine Dioxide

On the basis of gas chromatography(GC) coupled with a short capillary column and an electron capture detector(ECD), a simple and rapid method for the determination of five haloacetic acids(HAAs) in drinking water was developed by the optimization of derivation conditions and the modification of gas chromatographic program. HAAs formation potential(HAAFP) of the reaction of humic acid with chlorine was determined via this method. The major advantages of the method are the simplicity of chromatographic temperature program and the short run time of GC. Dichloroacetic acid(DCAA) and Trichloroacetic acid(TCAA), which were detected in the determination of HAAFP, were rapidly formed in the first 72 h of the reaction of humic acid with chlorine. HAAFP of the reaction of humic acid with chlorine increased with the increase in the concentrations of humic acid and chlorine. The average HAAFP of the reaction of humic acid with chlorine was 39.9 μg/mg TOC under the experimental conditions. When the concentration of humic acid was 4 mg/L, the concentration of HAAs, which were produced in the reaction of humic acid with chorine, may exceed MCL of 60 μg/L HAAs as the water quality standards for urban water supply of China and the first stage of US EPA disinfection/disinfection by-products(D/DBP) rule; when the concentration of humic acid was 2 mg/L, the concentration of HAAs may exceed MCL of 30 μg/L HAAs for the second stage of US EPA D/DBP rule. When humic acid was reacted with chlorine dioxide, only DCAA was detected with a maximum concentration of 3.3 μg/L at a humic acid content of 6 mg/L. It was demonstrated that the substitution of chlorine dioxide for chorine may entirely or partly control the formation of HAAs and effectively reduce the health risk associated with disinfected drinking water.     

Membrane purification of Cl2 gas: I. Permeabilities as a function of temperature for Cl2, O2, N2, H2 in two types of PDMS membranes

Permeability (P) of Cl₂, O₂, N₂ and H₂ was measured in polydimethylsiloxane (PDMS) composite membranes with two different degrees of cross-linking. The permeability was measured in the low pressure range (1–3 bar absolute) over a fairly large temperature range 35–120°C. The functionalities of the membranes were compared on the basis of permeation rate and ability to separate the gases Cl₂–O₂. These results are part of an extensive survey where perfluorinated and carbon membranes are also included (not reported here). The purpose of the project is to develop an industrial membrane with high permselectivity for either O₂ or Cl₂ (depending on the type of membrane) at temperatures preferably above 70°C. Process conditions are set in an industrial project. The PDMS membranes are good candidates for this separation, having a high permeation rate for Cl₂ and a selectivity of Cl₂/O₂ in the range of 8–25 depending on temperature. Durability of the PDMS membranes in this aggressive environment is found to be very dependent on process conditions and on how the material is polymerized and cured. For documentation of durability, various silicones were tested; these results are to be reported separately.     

ClONO2与O(3P)的反应机理

采用密度泛函方法Ｂ３ＬＹＰ／６－３１Ｇ研究了反应Ｏ（~（３）Ｐ）＋ＣＩＯＮＯ_２→ＣＩＯ＋ＮＯ_３和反应Ｏ（~（３）Ｐ）＋ ＣＩＯＮＯ_２→Ｏ_２＋ ＣＩＯＮＯ的反应机理．从动力学角度考察,计算结果表明,由于前一反应的活化势垒较低,因而是主要反应．该结果与大部分实验者的推论是一致的,对于后一反应,其两种反应途径的活化势垒较为相近,表明两种反应途径均是可能的．     

气相氯化氢资源化技术研究进展

氯化氢(HCl)是在各种工业过程中释放的有毒有害气体,但气相HCl中的氯、氢资源可以用于合成许多化工产品,这对副产HCl的资源化利用提供了思路。当前,气相HCl的综合利用主要集中在制氯气和其他含氯产品。通过综述气相HCl资源化的研究进展,分析了相关过程和机理,讨论了影响HCl资源化的因素,并强调了气体成分是影响副产HCl综合利用的主要因素,重点是其他气体成分对反应过程的影响。最后针对目前存在的资源化方式少、系统研究不足等问题,提出未来研究方向包括开发利用方式和模拟多组分气体条件等。     

Epoxidation by sodium chlorite with aldehyde-promoted chlorine dioxide formation

An improved method is described for selective room temperature epoxidation of alkenes by sodium chlorite in a solvent mixture of ethanol, acetonitrile, and water buffered at pH 7. In addition, the use of aldehydes as promoters in chlorite oxidations is described for the first time. The amount of sodium chlorite, the solvent mixture, and the addition of formaldehyde as a practical promoter were optimized. Styrene was used as a test substrate in the optimization studies and the generality of the method was assessed by using a variety of nucleophilic and electrophilic substrates. Yields up to 89% were obtained with styrene and other nucleophilic alkenes are readily converted into epoxides.     

氯气脱除技术研究进展

氯气(Cl₂)是一种对人体健康和大气环境有严重威胁的高毒性污染物,广泛存在氯碱工业的生产过程中,是含氯尾气的主要成分。含氯尾气的高效清洁脱除已成为研究重点与难点。吸附法和吸收法脱氯技术是目前主要的研究方向。本文以Cl₂的高效率脱除为目标、经济性脱除为理念、绿色化脱除为方向,综述了吸附法和吸收法技术的脱氯效果、机理和优缺点,并针对吸附法脱氯效率不足、吸附剂损耗大和吸收法操作条件繁琐、二次污染风险高等问题提出研究与发展方向。     

A novel and selective spectral method for the determination of trace chlorine in water basing on the resonance scattering effect of rhodamine B-I(3) association nanoparticles

In Na₂HPO₄-citric acid buffer solution, Cl₂ can oxidize I⁻ to form I₂ and then it reacts with excess I⁻ to form I₃⁻. The I₃⁻ combines respectively with rhodamine dyes, including rhodamine B (RhB), butyl rhodamine B (b-RhB), rhodamine 6G (RhG) and rhodamine S (RhS), to form association particles which give stronger resonance scattering (RS) effect at 400 nm. The RS intensity of the RhB, b-RhB, RhG and RhS systems is proportional to chlorine concentrations in the range of 0.008-1.74, 0.019-1.33, 0.021-2.11 and 0.019-2.04 μg/mL Cl₂, respectively. The detection limits of the systems were 0.0020, 0.0048, 0.0063 and 0.0017 μg/mL, respectively. In them, the RhB system has good stability and high sensitivity, and has been applied to the analysis of chlorine in drinking water, with satisfactory results which is in agreement with that of the methyl orange (MO) spectrophotometry.     

The adsorption of CCl4 on Ag(1 1 1): Carbene and CC bond formation

The adsorption of CCl₄ on Ag(1 1 1) has been investigated from 100 K to 300 K using absolute sticking probability measurement, temperature programmed desorption, Auger electron spectroscopy, low energy electron diffraction, ultra-violet photoelectron spectroscopy and X-ray photoelectron spectroscopy. At 100 K, CCl₄ adsorbs molecularly with a sticking probability of 1.0, forming a (3 × 3) adsorption structure. At 300 K the following overall reaction occurs,

2CCl_4(g)→4Cl_(chem)+C₂Cl_4(g),