极性大孔树脂XDA-8在提取工业咖啡因上的应用研究

以纯咖啡因的水溶液进行了静态吸附与解析实验,并以新华制药厂提供的咖啡因甲基化母液为原料进行了动态实验,考察了极性大孔树脂XDA-8对咖啡因的吸附性能,探讨了其实际应用的可行性。静态实验结果表明,在pH 6～7的水溶液中,树脂对咖啡因的吸附量达到最大,293 K下,树脂的最大理论吸附量可达432.9 mg/g干树脂;温度升高,树脂对咖啡因的吸附能力下降;动力学分析表明,树脂对咖啡因的吸附过程为液膜扩散控制。动态实验结果显示,XDA-8树脂能完全吸附4 BV(BV-树脂体积)甲基化母液中的咖啡因,对6 BV甲基化母液中咖啡因的吸附率达到97.5%以上,负载柱可用60%乙醇完全洗脱。     

离子交换树脂对咖啡因溶液提浓性能的研究

选用不同型号阳离子交换树脂和洗脱剂,对1%咖啡因溶液交换、洗脱过程进行研究。结果表明:相比于724、D-113、D-151树脂,732树脂交换处理量达10BV,洗脱速度快,单次洗脱浓度可达3.82%;80℃水更适合作为洗脱剂;经过3次叠加交换、洗脱后,1%咖啡因溶液提浓到7.39%,可为工业生产中结晶母液回收咖啡因过程提供参考。     

ADC发泡剂缩合母液综合利用新工艺

探讨了从ADC发泡剂缩合母液中提取联二脲、硫酸钠、氯化铵的工艺路线,反应条件及各种影响因素,小试结果表明:改进工艺后可从缩合母液中提取无水硫酸钠(平均质量分数为96.1%)、氯化铵(平均质量分数为95.6%);1 L缩合母液可回收联二脲1.61 g、硫酸钠133.4 g,氯化铵42.3 g.     

从茶叶中提取咖啡因

从茶叶中提取咖啡因研究的是从绿茶中提取咖啡因的一种可行性方案。用乙醇为溶剂,采用索氏提取器提取茶叶中的咖啡因,通过蒸馏回收乙醇后,再用升华法获取纯净的咖啡因晶体。     

茶碱钠盐甲基化反应的工艺研究

以1,3-二甲基黄嘌呤钠盐(茶碱钠盐)为原料,以碳酸二甲酯(DMC)作为甲基化试剂合成咖啡因。使用~1HNMR、~(13)CNMR和LC-MS等对咖啡因的结构进行了表征。考察了催化剂种类和用量、物料比[n(茶碱钠盐)∶n(DMC)]、反应温度、反应时间、母液循环次数对咖啡因收率的影响。结果表明,最佳的合成工艺条件为:以水为主的乳化液[m(水)∶m(乙二醇)∶m(OP-10)=14∶1∶1]为溶剂,茶碱钠盐的浓度为1.25 mol/L,催化剂Na Y用量为茶碱钠盐质量的5%,土耳其红油为乳化剂,其用量为茶碱钠盐质量的5%,n(茶碱钠盐)∶n(DMC)=1.00∶1.30,反应温度130℃,反应时间3 h。在此条件下,咖啡因的收率为97.8%。母液循环使用7次后,咖啡因的收率仍可达96.0%。     

茶叶中咖啡因的提取

本文对茶叶中咖啡因提取方式进行了比较,并通过单因素实验对茶叶中咖啡因的提取条件进行比较和优化,得出微波加热法提取茶叶中咖啡因的最佳提取条件。此法操作简单,安全环保,过程简捷,结果合理。     

茶叶中咖啡因的提取方法

咖啡因是从茶叶中提取出来的一种物质,属于生物碱类化合物。味苦,具有兴奋中枢神经的作用,现代医学研究表明咖啡因是一种中枢神经系统兴奋剂,它具有能促进新陈代谢,增强大脑皮层的兴奋,消除疲劳,并对心脏和肾脏的功能有影响,对人类的健康发挥着积极作用。目前,一般高校医用化学茶叶中咖啡因的提取方法为升华法,但据报道不同提取方法对咖啡因的提取率和产品纯度存在较大的差异。针对于此本人对目前茶叶中咖啡因提取方法进行相关综述。     

茶叶中咖啡因的提取研究

以黄山毛峰为原料,采用浸提法从茶叶中提取咖啡因。探讨了提取剂的种类、提取剂的加入量、提取时间、升华条件对咖啡因产品的收率的影响。研究结果表明,从茶叶中提取咖啡因最佳条件为:10g黄山毛峰,加入100mL乙醇提取2h,并用7g CaO的中和丹宁酸在184-186℃升华,最高收率为1.433%。     

药学专业实践教学“茶叶中咖啡因的提取与含量测定”的设计

"茶叶中咖啡因的提取"是药学专业有机化学课程实践教学中的一个很经典的实验,"茶叶中咖啡因的含量测定"在仪器分析课程实践教学中可设计成多种分析方法与手段进行,并且学生学以致用,创造性地应用到创新性实践项目中,使教学效果得以升华。本文具体介绍"茶叶中咖啡因的提取与含量测定"在药学专业实践教学中的设计,以及大学生创新项目设计的实践方案,旨在说明教师良好的实践教学能为学生自主学习和探索创造良好的科学氛围。     

从茶叶中提取咖啡因的实验研究进展

通过比较从茶叶中提取咖啡因的实验方法(浸提-升华法,微波提取-升华法,索氏提取-升华法和超声波提取-升华法)、提取溶剂(无水乙醇、乙醇水溶液、水、碳酸钙水溶液和有机溶剂)、茶叶和提取液的质量体积比、提取时间和茶叶种类总结了该实验的研究进展。广西龙州产的绿茶,采用索氏提取-升华并加入碳酸钠的提取方法,得到的咖啡因产率最大,为3.6%。咖啡因产率最低的是对碧螺春采用超声-升华法,咖啡因产率仅为0.28%。     

乙烯酮(双乙烯酮)下游产品废水的治理技术

乙烯酮(双乙烯酮)是十分重要的化工中间体,其下游产品较多。江苏某化工厂开发生产乙烯酮(双乙烯酮)下游产品三十多个,年生产规模三万多吨,是国内以乙烯酮(双乙烯酮)为中间体生产精细化学品的综合骨干企业。针对乙烯酮(双乙烯酮)下游产品废水特点,该厂结合企业实际,开展了产品优化,结构调整,清洁生产,资源循环利用,节水降耗等工作,从源头削减了污染物的生产。同时投资二千多万元新建预处理装置三套,6000m3/d废水生化处理装置一套,使全厂乙烯酮(双乙烯酮)下游产品的废水得到了有效的治理。     

几种乙炔加压设备性能的比较

阐述并比较了几种加压设备在乙炔加压清净过程中的性能和特点。     

三种煤样燃烧热的测定

本文通过三个厂家提供的三种煤样燃烧热的测定,由测定结果综合得出3号煤样燃烧最完全、燃烧热也最大,是三个煤样中最好的一种。     

Semi-empirical equation of state of metals. Equation of state of aluminum

A semi-empirical equation of state for metals is described. Its capabilities are demonstrated by the example of the equation of state for aluminum. New experimental data are presented on the location of the isentrope of aluminum for unloading from the state at p = 229.71 GPa on the shock adiabat to an aerogel (SiO₂) of density 0.08 g/cm³. __________ Translated from Fizika Goreniya i Vzryva, Vol. 44, No. 2, pp. 61–75, March–April, 2008.     

小议汽车涂装工艺设计对涂装成本的影响

论述了涂装工艺设计对涂装设备投资、涂装生产成本的影响。     

水泥水化热测定方法综述

水泥水化热是中、低热水泥和核电工程用水泥的一项关键的技术指标。全球范围内测定水泥水化热的方法有溶解法、直接法/半绝热法、等温传导量热法三种。本文总结了中、美、欧相关方法标准,对其测试原理、仪器设备、试验过程等方面进行了比对,并对其在领域的应用做了简单的概括。     

Measurement of the gradient of viscosity with composition of mixtures of non-ideal gases

A perturbation viscometer is a differential capillary viscometer that measures the logarithmic viscosity gradient of the viscosity-composition curve for gas mixtures. Measurements are made at different gas mixture compositions. Integration of the logarithmic viscosity gradients measured over the full composition range gives the mixture viscosity relative to the viscosity of one of the pure components of the gas mixture. This method is attractive because, for measurements of equal precision, integration of the gradients is potentially an order of magnitude more precise than measurement of the viscosities directly. It can also work at high and low temperatures and perhaps high pressures.The perturbation viscometer has been used to make measurements on ideal gas mixtures at ambient and elevated temperatures. The situation is more complicated when the gas mixtures are non-ideal. Extra effects due to density differences, molar volume change on mixing and differential thermal expansion may be measured in addition to the desired viscosity change producing systematic errors in the results. Thus, a more sophisticated apparatus is required. The standard perturbation viscometer has been modified to separate out the extra effects to permit measurement of the true change in viscosity. In addition, the theoretical operation of the modified apparatus has been revised to account for the design changes to permit calculation of the viscosity-composition profiles from the results.The apparatus has been tested using helium-HFC-125 mixtures and two new viscosity-composition profiles are presented for these mixtures at 23 and . Internal consistency tests have been used to confirm that the data produced are of high quality with an estimated uncertainty in the viscosity ratio data at of 0.9% and at of 1.5%.     

塔设备改造选型的分析

就当前扩产增容中塔设备设计和改造时板式塔和填料塔的选型问题加以分析。在评述目前国内常用的几种塔板和新型填料之后，着重介绍一种新型塔板（导向梯形浮阀塔板）和一种新型填料（波环填料——乾隆帕克）。     

Calorimetric and Computational Study of Enthalpy of Formation of Diperoxide of Cyclohexanone

A thermochemical rather simple experimental technique is applied to determine the enthalpy of formation of Diperoxide of ciclohexanone. The study is complemented with suitable theoretical calculations at the semiempirical and ab initio levels. A particular satisfactory agreement between both ways is found for the ab initio calculation at the 6–311G basis This set level. Some possible extensions of the present procedure are pointed out.     

Effect of degree of deacetylation of chitin on the properties of chitin crystallites

In the present article, chitin from crab shell was systematically deacetylated using a NaOH treatment with control of the reaction time. The degree of deacetylation, monitored using solid-state NMR, revealed that the reaction was pseudo-first order. Based on this, swollen and NaOH-saturated particles are proposed as the reaction system. The weight loss of the partially saponified and neutralized samples after HCl hydrolysis increased linearly with the degree of deacetylation. The crystallinity of the samples was found to increase after acid hydrolysis. According to conductimetric titration, the surface charge density of the crystallites, after acid hydrolysis, was found to increase with base treatment time. The effect of surface charge on the formation of a chiral nematic phase, due to the rodlike nature of the crystallites, was explored. These results show that because the contribution of charged particles to the ionic strength was significant the double layer compression was affected, especially since the surface charge density was close to the Manning limit. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:373–380, 1997