饮用水中挥发性有机物(VOCs)检测技术的研究进展

本文对饮用水中挥发性有机物(VOCs)的前处理方法和检测方法进行了综述。介绍了吹扫捕集技术、静态顶空技术、固相微萃取技术的原理及饮用水中VOCs检测中的研究进展。同时对气相色谱法、气质联用法的条件参数、应用状况进行了讨论。     

高锰酸钾与氯联用消毒控制饮用水中三卤甲烷生成量

主要考察了高锰酸钾与氯联用消毒工艺的化学安全性。研究了氯投量、高锰酸钾投量、Br^-浓度和pH值等因素对高锰酸钾与氯联用消毒工艺三卤甲烷(THMs)生成量及生成形态的影响。结果表明：氯投量对THMs生成量及生成形态有显著影响。随着氯投量的增大,THMs生成量显著升高,且溴代三卤甲烷(Br-THMs)占主要部分。高锰酸钾投量对THMs生成影响较小。THMs与Br-THMs的生成量随着Br^-浓度及pH值的升高而增加。与单独氯消毒工艺比较,高锰酸钾与氯联用消毒减少了氯投量,降低了THMs的生成量。高锰酸钾与氯联用消毒工艺在保障饮用水的化学安全性上优于单独氯消毒工艺。     

吹扫捕集-气相色谱法测定水中挥发性有机物

本文采用吹扫捕集进样,DB-624毛细管柱分离,FID检测器,外标法定量测定水中部分挥发性有机物,利用标准物质得到相应检出限,相对标准偏差,加标回收率。探讨实验中的一些问题并提出建议。     

探讨吹扫捕集气相色谱法测定饮用水中苯系物

吹扫捕集气相色谱法测定饮用水中的苯系物无需进行萃取等繁琐的样品前处理,操作简单灵敏。本文在设定的色谱和吹扫条件下,苯系物各组分线性方程的相关系数均大于0.9990,方法检出限在0.10～0.21μg·L-1,加标回收率在97～102%之间,适用于饮用水低浓度挥发性苯系物的测定。     

全自动吹扫捕集-气相色谱质谱联用仪测定饮用水源水中特定挥发性有机物的研究

将全自动吹扫捕集用于水中挥发性有机物的前处理,结合气相色谱质谱联用仪的优化条件,可达到25组分挥发性有机物的有效分离、定性和定量分析。在全扫描模式下,13组分挥发性有机物在2.5-25μg/L的范围内,工作曲线相关系数均大于0.990,检出限为0.5-1.7μg/L、测定下限为2.0-6.8μg/L;精密度RSD值范围为3.4%-11.6%;加标回收率范围为95.4%-114.1%,可实现水中挥发有机物大量样品的快速、高效、准确测定。     

水中二氯甲烷等五种挥发性有机物的测定

本文采用吹扫捕集/气相色谱/质谱法测定水中挥发性有机物,具有简便、快速、灵敏、准确等优点,适用于饮用水分析     

浅谈吹扫--GC／MS联用技术测定水中挥发性有机物

本文根据《地表水环境质量标准》（GB3838—2002）中的表3一集中式生活饮用水地表水源地中所列氯乙烯、三氯甲烷、四氯化碳等26个挥发性有机物的分析特点,将其加以归并,建立了采用吹扫捕集-气相色谱,质谱联用技术进行分析的方法,分析结果表明本方法所分析的26种目标化合物的回收率范围为88．5％～117％,精密度RSD％范围为0．71％-8．50％,检测限范围为O．10—0．61ug,L之间,均满足地表水中挥发性有机物的分析要求。     

吹扫捕集与气相色谱—质谱联用测定水中挥发性卤代烃

研究建立了吹扫捕集/气相色谱/质谱法测定水中挥发性卤代烃的分析方法,并利用该方法对不同水体中的该类物质进行了测定。11种挥发性卤代烃的最低检出限在0.08～0.33μg/L之间,水样的加标回收率为90％～105％,10μg/L的挥发性卤代烃标准溶液经6次重复测定后其相对标准偏差小于4％。     

吹扫捕集/气相色谱质谱联用法测定水中多种挥发性有机物的探讨

随着工业的不断发展,工业产生的有机污染越来越严重,尤其是人们赖以生存的水资源之中出现了多种挥发性有机物,严重的影响着饮用水的质量,威胁着人们的健康。为了进一步测定水中挥发性有机物含量,决定采用吹扫捕集,气相色谱质谱联用法,这种方法操作简单,灵敏度高、精确性强,线性范围较宽,可以检出限低,受到的干扰较小,可以用于水中多种挥发性有机物的测定工作。     

饮用水中主要消毒副产物及其检测方法的研究

本文简单介绍了饮用水中消毒副产物的产生及其危害,三卤甲烷作为主要消毒副产物对人体的危害。用气相色谱法对三卤甲烷进行检测,及其检测方法的研究。     

AAS、ICP-AES和HG-AFS在水质检测中的比较

对水质检测中测定金属元素经常使用的三种分析方法:原子吸收法(火焰法和石墨炉法)、电感耦合等离子体发射光谱法和氢化物发生-原子荧光光谱法。光谱的主要优缺点进行了比较。重点比较的内容有:水样的预处理步骤、干扰因素(包括光谱干扰、化学干扰、电离干扰)、各元素的检出限、线性范围、精密度和同时测定多元素能力的比较。     

聚芳醚腈砜的研究进展

介绍了聚芳醚腈砚的合成方法，并对其结构和性能进行了评述。     

荧光法同时测定环境水中的As(Ⅲ)和As(V)

研究了一种快速、灵敏的同时测定水中的As(Ⅲ)和As(V)的荧光新方法。在pH=6.5~7.5的缓冲介质中,利用2’,7’-二氯荧光素(DCF)作为荧光试剂,激发波长λex=510nm,发射波长λem=528nm下,As(Ⅲ)和DCF竞争碘,引起荧光强度的增强,从而测定痕量As(Ⅲ)。同时利用L一半胱氨酸还原剂将水中的As(V)还原成As(Ⅲ),从而测定As(Ⅲ)和As(v)的总量,差减间接测定As(V)。As(Ⅲ)浓度在4~180ng/mL范围内,相对荧光强度差值与As(Ⅲ)浓度呈线性关系,线性方程△F=7.82C+0.76,相关系数为o.9991,本法快速、简便、灵敏度高,已用于检测自来水和池塘水中痕量的As(Ⅲ)和As(V),回收率在96%~105%,结果令人满意。     

Equilibrium on line method (ELM) for imposition of Neumann boundary conditions in the finite point method (FPM)

Equilibrium on line method (ELM) for imposition of Neumann boundary conditions in the finite point method (FPM) is presented. In contrary to weak‐form‐based methods, strong‐form‐based methods such as the FPM are often unstable and less accurate, especially for problems governed by partial differential equations with Neumann (derivative) boundary conditions. In this paper, a truly meshless approach for imposition of Neumann boundary conditions in the FPM is proposed and adopted for 2D elasticity analyses. In the proposed method, equilibrium on lines on the Neumann boundary conditions is satisfied as Neumann boundary condition equations. Numerical studies show that this method for imposition of Neumann boundary is simple to implement and computationally efficient and also leads to more stable and accurate results. Copyright © 2006 John Wiley & Sons, Ltd.     

Wet oxidative method for removal of 2,4,6-trichlorophenol in water using Fe(III), Co(II), Ni(II) supported MCM41 catalysts

Chlorophenols in water are resistant to biological oxidation and they have to be destroyed by chemical oxidation. In the present work, Fe(III), Co(II) and Ni(II) incorporated MCM41 mesoporous solids were used as catalysts for oxidation of 2,4,6-trichlorophenol in water with or without the oxidant, H₂O₂. The catalysts were prepared by impregnation and were characterized by XRD and FTIR measurements. The parent MCM41, Fe(III), Co(II) and Ni(II) impregnated MCM41 had cation exchange capacity of 20.5, 25.5, 24.2, 26.0 mequiv./100 g, respectively. The catalysts were used after calcination at 773–873 K for 5 h. The reactions were carried out in a high pressure stirred reactor at 0.2 MPa (autogenous) and 353 K under various reaction conditions. The conversion achieved with Fe(III), Co(II) and Ni(II) incorporated MCM41 in 5 h is respectively 59.4, 50.0 and 65.6% with 2,4,6-TCP:H₂O₂ molar ratio of 1:1, and 60.2, 60.9 and 68.8% in absence of H₂O₂. The oxidation has a first order rate coefficient of (1.2–4.8) × 10⁻³ min⁻¹. The results show that introduction of Fe(III), Co(II) and Ni(II) into MCM-41 through impregnation produces very effective catalysts for wet oxidation of 2,4,6-trichlorophenol.     

Mg(Y,Gd)_4Si_3O_(13)∶Eu,Bi 的溶胶-凝胶法合成、结构和发光性能

采用溶胶-凝胶法首次合成出 MgY_(4-x-y-z)Si_3O_(13)∶Eu_z~(3+),Bi_y~(3+),Gd_x~(3+)系列发光体.其结构与ASTM 卡片记载的 MgY_4Si_3O_(13)的结构相同,属于六方晶系.在每 mol 基质中,Eu~(3+)、Bi~(3+)和 Gd~(3+)的最佳掺杂量分别为0.07,0.025和0.2mol.在发光体由非晶态向晶态的转变过程中,Eu~(3+)的发光强度和所处位置对称性都发生了显著变化.当基质以 Eu~(3+)、Bi~(3+)共掺杂时,Bi~(3+)的兰色发光和 Eu~(3+)的橙红色发光都很强,但 Bi~(3+)向 Eu~(3+)的能量传递效率很低,适量的 Gd~(3+)的加入可增强 Bi~(3+)对Eu~(3+)发光的敏化效果.     

厚膜电阻材料的物化特性对钌系厚膜电阻应变系数的影响

通过对厚膜电阻导电相、玻璃相的粒径控制、粒径比搭配以及在导电相、玻璃相中掺杂,研制成一种厚膜力敏电阻浆料,其应变系数GF可达15～17、工作温度可达150℃.介绍了厚膜力敏应变系数的测量方法,研究了厚膜电阻材料的物化特性对钌系厚膜电阻应变系数的影响,探讨了提高应变系数的技术途径,同时,对其导电机理作了简要的阐述.     

Theoretical aspects of the smoothed finite element method (SFEM)

This paper examines the theoretical bases for the smoothed finite element method (SFEM), which was formulated by incorporating cell‐wise strain smoothing operation into standard compatible finite element method (FEM). The weak form of SFEM can be derived from the Hu–Washizu three‐field variational principle. For elastic problems, it is proved that 1D linear element and 2D linear triangle element in SFEM are identical to their counterparts in FEM, while 2D bilinear quadrilateral elements in SFEM are different from that of FEM: when the number of smoothing cells (SCs) of the elements equals 1, the SFEM solution is proved to be ‘variationally consistent’ and has the same properties with those of FEM using reduced integration; when SC approaches infinity, the SFEM solution will approach the solution of the standard displacement compatible FEM model; when SC is a finite number larger than 1, the SFEM solutions are not ‘variationally consistent’ but ‘energy consistent’, and will change monotonously from the solution of SFEM (SC = 1) to that of SFEM (SC → ∞). It is suggested that there exists an optimal number of SC such that the SFEM solution is closest to the exact solution. The properties of SFEM are confirmed by numerical examples. Copyright © 2006 John Wiley & Sons, Ltd.     

低温共熔盐法制备LiNi_(0.8)Co_(0.2)O_2的结构与电化学性能

低温共熔盐0.434LiNO3-0.266LiOH·H2O-0.3CH3COOLi·2H2O在80～90℃范围实现很好的熔融态。采用这种低温共熔盐制备出了锂离子电池正极材料LiNi0.8Co0.2O2,XRD检测显示材料结晶度高,具有规整的层状α-NaFeO2结构,SEM扫描显示样品形貌均一,颗粒大小均匀。充放电测试表明,材料具有良好的电化学性能,在2.8～4.3V电压范围0.2C首次放电比容量为174.1mAh/g,循环20次后容量保留95%。