排序方式: 共有27条查询结果,搜索用时 115 毫秒
11.
采用甲基异丁基甲酮溶解松香,用0.1mol/L盐酸作为水相反萃取其中的重金属,用火焰原子吸收光谱法对铁、镍、铜、铅、锌的含量进行测定。并且探讨了该方法搅拌时间对测定结果的影响及多次测定的重现性。该方法铁、镍、铜、铅、锌的平均回收率为90.9%—95.5%,RSD为1.8%—5.3%,检出限为0.01—0.25mg/L。 相似文献
12.
13.
14.
15.
Determination of resin acid composition in rosin samples using cyclodextrin‐modified capillary electrophoresis 下载免费PDF全文
Louise Mckeon Fiona Regan Barry Burns Ray Leonard 《Journal of separation science》2014,37(19):2791-2796
Rosins are used in a wide variety of industries in varnishes, adhesives, drug coatings, etc. In this project a novel capillary electrophoresis method was developed to investigate the resin acid composition of rosins. The acids were separated and the concentrations of individual acids present in gum rosin samples determined in order to investigate any links between the presence and concentration of these acids and the tendency of rosins to crystallize. The capillary electrophoresis method successfully separated nine resin acids in various rosin samples where previously they could not all be separated. Calibration curves were created to determine acid concentration. Abietic, dehydroabietic, neoabietic, pimaric, isopimaric, levopimaric, sandaracopimaric, palustric, and 7‐oxo‐dehydroabietic acids were separated using a 20 mM tris buffer at pH 9 containing 15% methanol 5 mM (2‐hydroxypropyl)‐γ‐cyclodextrin 10 mM sulfobutylether‐β‐cyclodextrin. Their concentrations in a crystallizing and a noncrystallizing rosin sample were determined. 相似文献
16.
17.
Sourav Sarkar Achintya Mukhopadhyay Swarnendu Sen 《Combustion Theory and Modelling》2019,23(4):626-650
Water, sprayed in the form of tiny droplets, has emerged as a potential fire suppressant after the halon compounds such as trifluorobromomethane (CF3Br, Halon 1301) were banned by the Montreal protocol. The size distribution of the water droplet plays a crucial role in the effectiveness of the water spray in fire suppression. A numerical investigation of the influence of size distribution of a polydisperse water spray on extinction of counterflow diffusion flames is presented in this paper. This study uses laminar finite rate model with reduced CHEMKIN chemistry for numerical simulations. The discrete phase, namely the water spray, is simulated using Lagrangian Discrete Phase Modelling approach. In this work, the polydispersity of water spray is taken into account in the numerical simulation by a suitable Rosin–Rammler distribution. Results obtained from numerical simulation are validated with the experimental results reported in the literature. This study demonstrates that the representation of the polydisperse spray by a monodisperse spray (with droplet diameter same as the SMD of the polydisperse spray) in numerical simulations is not always justified and it leads to deviation from the experimental results. The effects of number mean diameter and spread parameter on the efficacy of flame suppression are investigated for polydisperse sprays. A comprehensive comparison is done between the effectiveness of monodisperse and polydisperse water sprays. An optimum droplet diameter is obtained for monodisperse sprays for which the effectiveness of the spray is maximum. The effects of evaporation Damköhler number and Stokes number of water droplets on flame suppression have also been explained. 相似文献
18.
19.
Woo-il BaekR. Nirmala Nasser A.M. BarakatMohamed H. El-Newehy Salem S. Al-DeyabHak Yong Kim 《Applied Surface Science》2011,258(4):1385-1389
In this study, we describe the first reported preparation of rosin in fiber form through use of an electrospinning technique utilizing various solvent systems. The polymer concentration of the formed fiber was studied by using various solvents such as chloroform, ethanol, N-N dimethylformamide (DMF), tetrahydrofuran (THF), acetone, and methylene chloride (MC). An electrospray of the solution resulted in the beaded form of the rosin. By varying the polymer concentration with MC, we were then able to obtain uniform fibers. However, the fibers exhibited large diameter. We believe that it is possible to reduce the diameter of the rosin fibers through appropriate selection of electrospinning parameters. In addition, the morphological transitions from beads, to beaded fiber, to fiber were studied at different polymer concentrations. We propose a possible physical cross linking mechanism for the formation of rosin fibers during the electrospinning process. Our results demonstrate the feasibility of producing fiber nanostructures of rosin by using an electrospinning technique. 相似文献
20.
枞酸和松香在紫外光辐照下的氧化反应动力学 总被引:1,自引:0,他引:1
设计了紫外光辐照下枞酸和松香的氧化反应装置,采用紫外分光光度法实时测定它们的氧化反应过程,计算氧化反应动力学常数(kb)和反应活化能(Ea),考察光量子产率(Φ)和光强度(I)对氧化反应动力学的影响.结果表明,枞酸和松香的光氧化反应均呈表观一级反应,它们的速率常数的对数与光强度的对数均呈线性关系.枞酸在20,25和35℃下的关系式分别为:lnkb=0.9911lnI-8.860,lnkb=0.8786lnI-8.069和lnkb=0.8364lnI-7.690.松香于20℃下的关系式为:lnkb=1.204lnI-10.49.枞酸初始反应的光量子产率Φ为0.471.且枞酸在不同光强度下的活化能与光强度的对数成线性关系,线性方程为:Ea=-7.549lnI+60.02. 相似文献