Properties of Dispersion of Multiwalled Carbon Nanotubes as Cutting Fluid

This article presents the results of experiments performed to evaluate properties of dispersion of multiwalled carbon nanotubes (MWCNT) in water with sodium dodecyl sulfate (SDS) as a dispersant. Different samples of varying concentrations of MWCNTs were prepared for the analysis and properties including thermal conductivity, pH value, viscosity, wettability, etc., were evaluated. These properties were compared with the properties of conventional cutting fluid, which was taken as a mix of water and mineral oil. It was found that the thermal conductivity of the MWCNT dispersion was higher than the conventional cutting fluid by about 42%. There was a decrease in contact angle by about 70%. Thus, dispersing MWCNTs in water with SDS increases the thermal conductivity and wettability of fluid. The pH value of fluid with 0.2 vol% MWCNTs was found to be 8.4. It thus reduced the corrosive nature of water. Nanoparticles of MWCNTs did not have much influence on the viscosity of the base fluid. Thus, the use of MWCNTs in water with SDS appeared to result in a better cutting fluid for machining than conventional cutting fluid.     

5-Br-PADAT分光光度法测定痕量钴

本文提出了测定微量钴的新方法,研究了在SDS存在下,5-Br-PADAT与钴的显色反应条件,在pH4的缓冲溶液中,钴与5-Br-PADAT生成深红色络合物。其络合物组成为1:3,摩尔吸光系数为6.6×10~4,0～15μgCo(Ⅱ)/25ml符合比尔定律。拟定的方法甩于伟晶岩、含铜硅卡岩中钴的测定,结果满意。     

Extraction of erythromycin‐A using colloidal liquid aphrons: I. Equilibrium partitioning

Colloidal liquid aphrons (CLAs) are surfactant‐stabilised solvent droplets which have recently been explored for use in pre‐dispersed solvent extraction (PDSE). In this work, the equilibrium partitioning of a microbial secondary metabolite, erythromycin, has been studied using both CLAs (formulated from 1% (w/v) Softanol 120 in decanol and 0.5% (w/v) SDS in water) and surfactant‐containing, two‐phase systems. The equilibrium partitioning of erythromycin was found to be strongly influenced by the extraction pH, and exhibited a marked change either side of the pK_a of the molecule. A modified form of the Henderson–Hasselbach equation could be used as a simple design equation to predict the equilibrium partition coefficient (m_eryt = C_org /C_aq) as a function of pH. For extraction experiments with dispersed CLAs where pH > pK_a, m_eryt values as high as 150 could be obtained and the erythromycin could be concentrated by factors of up to 100. Experiments were also carried out in surfactant‐containing, two‐phase systems to determine the effect of individual surfactants used for aphron formulation on erythromycin partitioning. For extraction at pH 10 neither the Softanol (a non‐ionic surfactant) nor SDS (an anionic surfactant) had any influence on the equilibrium erythromycin partition coefficients. For stripping at pH 7, however, it was found that recovery of erythromycin from the organic phase decreased with increasing concentration of SDS, although again the Softanol had no influence on the equilibrium. The effect of SDS was attributed to a specific electrostatic interaction between individual erythromycin and SDS molecules under stripping conditions. The m_eryt values and concentration factors achievable in the two‐phase systems were considerably less than those for the PDSE experiments. The physical properties of the two‐phase systems, ie density, viscosity, interfacial tension, etc, and the equilibrium distribution of the surfactants were also determined in relation to subsequent studies on the kinetics of erythromycin extraction. © 2000 Society of Chemical Industry     

水性聚氨酯-SiO2/TiO2复合涂料的制备与研究

本文采用溶胶-凝胶法,用钛酸四丁酯与正硅酸乙酯制备了纳米级SiO2／TiO2复合微粒,将其分散在聚醚型水性聚氨酯中,制备了新型水性聚氨酯-SiO2／TiO2复合涂料。傅立叶变换红外光谱及透射电镜测试表明纳米TiO2颗粒表面成功地包覆上SiO2,在聚氨酯乳液中复合微粒粒径为60nm左右;分光光度法测试表明TiO2质量分数为20％的复合微粒在聚氨酯水乳液中具有良好的分散性能,而加入质量分数为1％的十二烷基磺酸钠后,对SiO2／TiO2纳米粉末的分散性能改善最大;力学性能测试表明加入SiO2／TiO2纳米复合微粒能有效提高水性聚氨酯的力学性能,当复合微粒质量分数为0.6％时,其力学性能达到最佳。     

SDS对香豆素在SB-16胶束增溶行为影响

为了模拟药物香豆素在十二烷基硫酸钠(SDS)和十六烷基磺基甜菜碱(SB-16)复配体系中的分配规律,采用分子动力学的方法模拟了香豆素分子(C-343)在SB-16水溶液中的增溶行为,在上述溶液的基础上又继续添加了表面活性剂SDS,并研究了SDS对香豆素在SB-16胶束增溶行为影响。研究结果表明,在298 K,101.3 kPa下的平衡条件下,C-343可以自发地增溶到SB-16球形胶束中。SDS分子的烷基尾链部分插入到SB-16球形胶束内部,并在SB-16表面形成一层疏水基团在内,亲水基团在外的SDS分子薄层。C-343分子在SDS分子的疏水作用和静电作用下,从SB-16胶束内部逐步迁移至SDS胶束的外层表面上。从理论证实了添加表面活性剂可以对药物分子在胶束溶液中的增溶与释放过程进行有效控制,以期为该类体系的试验研究提供理论依据。     

几种提取转基因木瓜DNA的方法比较

目的 比较CTAB法、SDS法及试剂盒法分别提取木瓜果皮、果肉、种籽DNA的效果, 以提高转基因木瓜的检测准确率。方法 对转基因木瓜内源基因Papain及外源基因NPTII、CP进行普通PCR, 同时对基因表达零件CaMV35S启动子和NOS终止子进行荧光PCR, 以检测提取DNA的质量。结果 分析电泳产物发现, SDS法提取木瓜种籽样品的DNA未能适合普通PCR检测的要求, 其他方法均能满足普通PCR要求。荧光PCR结果显示, 3种方法提取的DNA都满足荧光扩增要求。结论 比较3种提取方法及3种木瓜材料, 发现用CTAB法或SDS法以果皮为材料提取DNA质量最佳。     

十二烷基磺酸钠改性纳米CeO2的研究

采用十二烷基磺酸钠(SDS)对纳米CeO2粉体进行表面改性以提高其在有机材料中的分散性,以活化指数表征改性效果,并用IR、TG-DSC、TEM和LPSA表征了改性纳米CeO2的效果和结构。结果表明,最佳改性工艺条件为:十二烷基磺酸钠用量4%,反应温度70℃,反应时间6h,pH=7。SDS以化学键合的方式吸附在纳米CeO2的表面,并形成了有机包覆层,经SDS改性过的纳米CeO2的分散性明显提高,粒度降低44%。     

表面活性剂（C12）脂肪醇聚氧乙烯（5）醚与十二烷基硫酸钠的复配

进行了非离子表面活性剂(C12)脂肪醇聚氧乙烯(5)醚(简为AE05)与阴离子表面活性剂十二烷基硫酸钠(简为SDS)的复配研究,试图找出它们之间较佳的协同增效配比.     

温度对高浓度SDS水溶液泡沫稳定性及分离的影响

高浓度表面活性物质的分离是泡沫分离过程的难题,也是制约泡沫分离技术应用于工业化生产的瓶颈.为了解决高浓度表面活性物质泡沫分离的难题,以阴离子表面活性剂十二烷基硫酸钠(SDS)水溶液为体系,研究了在其临界胶束浓度(CMC)附近时,温度对SDS水溶液气泡直径、泡沫稳定性、富集比及回收率的影响.结果表明:温度对高浓度表面活性物质的泡沫分离有显著影响.当SDS水溶液浓度分别为1.2、2.3、3.5g·L-1,温度从30℃升高到70℃时,泡沫稳定性先增大后减小,在pH 6.9、表观气速2.4×10-3 m·s-1、装液量200 mL的操作条件下,气泡直径先减小后增大,富集比提高了3～5倍,回收率降低了34％～65％.