加碱萃取精馏制取无水乙醇

乙醇-水体系存在共沸点,难以通过普通精馏方法制取高纯度乙醇,萃取精馏是分离共沸体系的有效途径。目前常用的萃取溶剂是乙二醇。在分离乙醇-水体系的过程中,将适当的盐类(醋酸钾)溶于乙二醇形成溶盐萃取剂,会有效提高溶剂的选择性。本文用萃取精馏方法并加入乙二醇分离效果更明显。     

Gaussian与Aspen Plus在化工原理课程设计中的应用*

在化工原理课程设计中将某药厂委托的科研项目“二甲硫醚、甲醇和水分离设计项目”转化为典型教学案例,结合现代计算机辅助技术,引入量化计算软件Gaussian和化工模拟软件Aspen Plus分别从微观和宏观上进行萃取精馏分离共沸物的设计。通过Gaussian软件,基于密度泛函理论证实了待分离体系中已有的组分水可改变二甲硫醚与甲醇二元共沸物的相对挥发度,消除2者之间的共沸。继而采用Aspen Plus软件对待分离混合液进行萃取精馏工艺模拟与优化,最后开展工业设计与设备选型。上述实际案例的设计过程,创造性地使用了混合液已有的组分作为萃取剂,通过萃取精馏工艺实现共沸物的分离,弥补了传统萃取精馏因引入萃取剂导致产品携带少量第三组分的缺点,极大地激发了学生学习的兴趣,丰富了课程教学内容,将复杂的萃取精馏过程讲解透彻,促进教学质量的提升,增强学生的工程设计能力,学生多次参加全国大学生化工设计竞赛并取得了优异成绩。     

乙酸乙酯-乙醇-水-甘油体系中部分组分之间汽液平衡数据的测定及关联

生产乙酸乙酯的产物乙醛、乙醚采用精馏容易脱除,乙酸乙酯、乙醇、水形成二元、三元共沸物,则难以分离,共沸法和萃取精制乙酸乙酯,工艺较复杂,能耗大;复合萃取一次可得99％以上乙酸乙酯,同时可得95％以上乙醇,用水量仅为原料量的2倍,工艺简单,能耗低。本文测定乙酸乙酯、乙醇、水在甘油中的γ^∝及二元体系的VLE数据,由三对二元体系模型参数计算乙酸乙酯-水-甘油及乙酸乙酯一乙醇一甘油的VLE数据,为萃取模拟计算及试验提供基础数据。     

萃取精馏过程的非平衡态热力学分析

对萃取精馏过程进行了非平衡热力学分析,提出了分离过程得以进行的判据.推导出了熵产生的数学表达式,并可将其用于萃取精馏过程的节能分析.此项研究结果只适用于萃取精馏板式塔,且在非平衡热力学的线性区域内     

Aspen plus在“物理化学”课程精馏分离中的教学应用

将Aspen Plus化工流程模拟软件运用到工科“物理化学”课程精馏分离过程教学中,结合二甲醚(DME)-甲醇-水三元体系精馏分离的科研成果案例,探讨了Aspen Plus软件在精馏分离过程教学中的应用。实践表明,采用流程模拟软件辅助精馏分离的教学方法,不仅有助于加深学生对精馏分离理论知识点的理解,提高课程教学质量,而且有助于培养学生利用流程模拟技术解决工程实际问题的能力,提升了学生的综合素质。     

水产品中邻苯二甲酸酯类增塑剂存在状态研究及其双水相提取测定

利用荧光猝灭法与GC-MS研究了邻苯二甲酸酯类(PAEs)在以蛋白质为主要基质的水产品中的存在状态,探讨了蛋白质对PAEs萃取率的影响。结果表明,PAEs可通过氢键和范德华力与蛋白质牢固结合;体积分数为80%的异丙醇水溶液可引起蛋白质缓慢变性、使结合的PAEs充分离解,通过异丙醇-无机盐-水双水相体系实现PAEs的高效萃取。由于80%的异丙醇水溶液极性较强,与PAEs共同进入双水相上相的脂溶性杂质较少,萃取液净化步骤大大简化。在双水相上相中加入无水MgSO4、N-丙基乙二胺(PSA)去除水分与杂质后直接进样进行GC-MS检测。该方法用于水产品中五种PAEs的测定,回收率为81.9%～92.7%,相对标准偏差为1.2%～4.8%。     

饲料中克伦特罗和沙丁胺醇分离方法的研究

研究了用液-液萃取和固相萃取两种方法同时分离饲料中克伦特罗和沙丁胺醇．液．液萃取法中，采用乙酸乙酯 正己烷 异丙醇混合溶剂，克伦特罗和沙丁胺醇萃取率分别可达85．20％、83．00％：固相萃取法中，采用Amberlite XAD-2大孔吸附树脂，效果较液．液萃取更好。萃取率为91．25%和86．10％．两种分离方法用于饲料中克伦特罗和沙丁胺醇的测定。结果满意．     

氯仿萃取分离N,N-二甲基甲酰胺工艺

针对某制药企业生产过程中产生的高浓度含N,N-二甲基甲酰胺(DMF)料液，在折流板萃取塔内进行连续萃取分离，结合精馏工艺，实现了DMF的分离与回收。对于DMF初始质量分数为38.46%的料液，以氯仿作为萃取剂，采用脉冲折流板萃取塔对料液中的DMF进行萃取，研究了不同油水相比、流量和脉冲条件下在折流板萃取塔中DMF的萃取效果。结果表明，DMF的萃取效率随着脉冲的加入、油水相比的升高和两相流速的增大而增大，在优化的条件下DMF的萃取率最高为99.94%，分离后的萃余相DMF质量分数达到0.5%以下。进一步，对于负载了DMF的氯仿溶液，分别进行了间歇精馏实验和模拟计算，结果显示通过精馏可以实现氯仿和DMF的有效分离回收。     

乙醇水溶液与二乙氧基甲烷的萃取分离

目前DEM与乙醇水溶液的分离均采用精密精馏法[1],由于DEM的沸点与乙醇水溶液的共沸点接近,很难得到98%以上的DEM,本文以二甘醇为萃取剂,以UNIQUAC方程为模型[6],采用微机模拟逆流萃取分离结果,并进行逆流萃取试验。1　逆流萃取模拟计算以UNIQUAC方程为模型,采用二甘醇为逆流图1　液液萃取工艺流程Fig.1　liquid liquidextractiontechnicalchart萃取剂模拟计算DEM与乙醇水溶液的分离结果,工艺流程如图1所示,塔顶为萃余相③,含高纯度的DEM,塔底为富含乙醇和水的萃取相②,萃取相送精馏塔分离,精馏塔底溶剂循环使用,塔顶可得到…     

一种丁醇和乙酸丁酯的分离方法

本发明公开了一种丁醇和乙酸丁酯的分离方法,通过加入萃取剂,采用萃取精馏方法对丁醇和乙酸丁酯混合物进行分离,萃取剂能改变丁醇和乙酸丁酯的相对挥发度,发生较大的变化,从而使丁醇和乙酸丁酯更容易分离开,得到纯度较高的乙酸丁酯和丁醇,同时加入的萃取剂也可以有效的回收,实现循环利用。     

Enantiomeric enrichment of partially resolved N-methyl-amphetamine

The enantiomeric enrichment of N-methyl-amphetamine (MA) was tried by eight different preparative separation methods. The enrichment process was also studied by thermoanalitical methods (DSC,TG). There is no enantiomeric enrichment during fractional distillation and selective extraction of the liquid base. The enantiomeric mixture of MA·HCl can be enriched by crystallization or by sublimation. The most effective enrichment can be achieved by fractional crystallization or distillation of the reaction mixture after partial salt formation with hydrochloric acid. The separation is less effective in case of fractional steam distillation and selective extraction when the enantiomer and the racemate are distributed between two liquid phases. This supports the general experience that having a solid phase in the system makes enantiomer separation more efficient.This revised version was published online in November 2005 with corrections to the Cover Date.     

Purification of 3-hydroxypropionitrile by wiped molecular distillation

3-hydroxypropionitrile (HPN) is widely used asmaterials in many organic reactions such as synthe-sizing medicine, pesticide and polymeric compound.Since the 1970s, HPN has mostly been synthesizedwith the reaction of acrylonitrile and H2O catalyzed byNaOH aqueous solution, and the mole yield of HPN isabove 85%. However, the HPN must be separatedfrom the acrylonitrile hydration mixture and get rid ofwater, salt and other side products. The traditional separation method is evapora-tion…     

Prediction of Separation Factors Using Group Contribution Methods a Review

For separation process design calculations such as distillation, absorption and extraction it is unconditionally necessary to have quantitative information on the mixtures in consideration, i.e. knowledge about phase equilibrium compositions, heats of mixing etc.     

Ionic liquids in separations of azeotropic systems – A review

Efforts to make existing separation methods more efficient and eco-friendly may get a boost from the use of a relatively new class of compounds known as ionic liquids (ILs). The separation of azeotropic mixtures has conventionally been one of the most challenging tasks in industrial processes due to the fact that their separation by simple distillation is basically impossible.This paper provides a critical review of methods using ILs as azeotrope breakers. Three separation processes were addressed: liquid–liquid extraction, extractive distillation, and supported liquid membranes. We examine the azeotrope breaking potential of ILs and compare their performance to that of conventional solvents. A systematic analysis of the influence of the structure of ILs on their azeotrope breaking capacity contributes to the establishment of guidelines for selecting the most suitable ILs for the separation of specific azeotropic mixtures.     

Separation with Supercritical Gases: Practical Applications

Extraction with supercritical gases combines, to a certain extent, the characteristics of both distillation and extraction; the term “destraction” is therefore proposed for this method of separation. The principles of the method are illustrated in this article by a series of color photographs comparing extraction and destraction. Of the practical uses of this new method may be mentioned the separation of cod-liver oil into 50 fractions, each differing in saponification value and iodine number, by means of supercritical ethane and, in particular, the decaffeination of raw coffee with supercritical carbon dioxide.     

Recovery of Vanillin and Syringaldehyde from Lignin Oxidation: A Review of Separation and Purification Processes

Lignin is an underexploited side-stream of pulp and paper industry and biorefineries, being used for energy production at mill site or as low value material for dispersants or binding applications. However, an integrated process of reaction and separation can be implemented for the production of high added-value monomeric phenolic chemicals such as vanillin and syringaldehyde. In this review, the main research advances in the recovery of vanillin and syringaldehyde resulting from oxidation of lignin are addressed, covering various separation methodologies namely liquid-liquid extraction, supercritical fluid extraction, distillation, crystallization, membrane separation, and adsorption. Studies in this area started in the early years of the 20^th century, but in the last decades several processes have been suggested, mainly for vanillin separation. Finding the ultimate industrially feasible process is still a necessary task and this review points out the most promising technologies and sequence of processes.     

Using Diaminomethanal as an Entrainer for the Separation of Isopropanol + Water Mixture

Journal of Solution Chemistry - Diaminomethanal (an organic compound), was examined as entrainer for dehydration of isopropanol?water system by extractive distillation. Isobaric...     

Analysis of ochratoxins from buffered rumen fluid by reversed-phase high-performance liquid chromatography (HPLC)

Summary An efficient procedure for the extraction and analysis of ochratoxins A, B, C and α from buffered rumen fluid has been developed. The samples have been cleaned up byliquid-liquid extraction and the separation of chratoxins was by isocratic elution on a 5μm C₁₈ ODS-column which 0.083 M phosphoric acid/acetonitrile/isopropanol (55/35/10).     

Membrane Distillation and Related Operations—A Review

Abstract

Membrane contactors represent an emerging technology in which the membrane is used as a tool for inter phase mass transfer operations: the membrane does not act as a selective barrier, but the separation is based on the phase equilibrium. In principle, all traditional stripping, scrubbing, absorption, evaporation, distillation, crystallization, emulsification, liquid‐liquid extraction, and mass transfer catalysis processes can be carried out according to this configuration. This review, specifically addressed to membrane distillation (MD), osmotic distillation (OD), and membrane crystallization (MCr), illustrates the fundamental concepts related to heat and mass transport phenomena through microporous membranes, appropriate membrane properties, and module design criteria. The most significant applications of these novel membrane operations, concerning pure/fresh water production, wastewater treatment, concentration of agro food solutions, and concentration/crystallization of organic and biological solutions, are also presented and discussed.     

RP-HPTLC densitometric determination and validation of vanillin and related phenolic compounds in accelerated solvent extract of Vanilla planifolia*

A simple, fast and sensitive RP-HPTLC method is developed for simultaneous quantitative determination of vanillin and related phenolic compounds in ethanolic extracts of Vanilla planifolia pods. In addition to this, the applicability of accelerated solvent extraction (ASE) as an alternative to microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE) and Soxhlet extraction was also explored for the rapid extraction of phenolic compounds in vanilla pods. Good separation was achieved on aluminium plates precoated with silica gel RP-18 F(254S) in the mobile phase of methanol/water/isopropanol/acetic acid (30:65:2:3, by volume). The method showed good linearity, high precision and good recovery of compounds of interest. ASE showed good extraction efficiency in less time as compared to other techniques for all the phenolic compounds. The present method would be useful for analytical research and for routine analysis of vanilla extracts for their quality control.