Pervaporation for the Separation of Methyl Ethyl Ketone from Binary Process Mixtures

Abstract

The separation of methyl ethyl ketone (MEK) from binary process mixtures containing water and ethanol has been examined. These studies demonstrate the capability of pervaporation membranes to effectively separate MEK from various process streams in industry. Extensive organic permeation studies were performed using silicone composite membranes to evaluate the effect of temperature, permeate-side pressure, and feed concentration on flux and selectivity. Two organophilic membranes, a high selectivity low flux membrane and a low selectivity high flux membrane, were compared. Dehydration of a MEK-water mixture was also effectively performed with a polyvinyl alcohol composite membrane. MEK was separated only slightly from an ethanol mixture using a silicone membrane.     

A Silicon Microseparator based Pervaporation Process for Separation of Ethanol/Water Mixtures using a Polymer Membrane

Abstract

The selective removal of water from ethanol through pervaporation was demonstrated in a microchannel device using a commercial membrane. Photolithography and dry etching techniques were employed for fabrication of the microseparator with hydraulic diameters of 30 µm to 80 µm. Experiments conducted at 90°C and 2–3 Torr, with Reynolds Numbers ranging from 8 to 91, resulted in an average water and ethanol permeance of 1.2×10^?3 and 8×10^?5 cm³/cm² · s · cmHg respectively. A mass transfer analysis involving Sherwood correlations was used to calculate the theoretical boundary layer resistance. The comparison of overall mass transfer coefficient with the boundary layer coefficients suggests that the membrane was the dominant resistance for this system.     

Aqueous Membranes for the Separation of Gaseous Mixtures

Abstract

Gas mixture separation characteristics of aqueous surfactant films were studied. Permeation constants of carbon dioxide, oxygen, nitrogen, helium, and propane through aqueous films of 2 wt% Ivory Liquid and of 2 wt% Duponol WN were determined. Binary gas mixtures of carbon dioxide-nitrogen and carbon dioxide-propane were enriched in one of the components using a thermally induced driving force.     

Separation of Tetrahydrofuran from Aqueous Mixtures by Pervaporation

Abstract

Studies on the separation of tetrahydrofuran (THF) and water by pervaporation were conducted. A silicalite-filled silicone composite membrane was used for organic permeation and a polyvinyl alcohol composite membrane for dehydration. Effects of feed concentration, feed temperature, permeate-side pressure, and type of membrane were studied. The silicone composite membrane yielded a selectivity of 205 and a THF flux of 1.1 kg/m²·h at benchmark conditions of 50°C feed temperature, 2 torr permeate-side pressure, and a feed concentration of 4.4% w/w THF. An increase in temperature increased the flux exponentially in an Arrhenius-type manner, but had little effect on selectivity. These data show that the trend agrees with an Arrhenius-type relationship. An increase in feed concentration increased the flux, but the selectivity for THF decreased. As the permeate-side pressure increased, the flux decreased in a sigmoidal fashion, but the selectivity for THF increased. Some initial studies on dehydration were also performed. Use of pervaporation in a solvent recovery/reuse system in industry has also been examined.     

溶析结晶法分离提纯对二氯苯的研究

提出了溶析结晶法从邻、对位二氯苯混合物中分离提纯 地二氯苯的新工艺。选用乙醇作为主溶剂,水作为析出剂,测定了物系的溶解度关系。研究了溶剂配比,结晶温度,投料比等工艺操作条件对产品收率和纯度的影响。实验证明,在温度为5－10℃,溶剂体积比（水：乙醇）为0.25-0.35的条件下,采用溶析结晶法可从对二氯苯含量为77％－85％的原料中,分离出纯度为99.7％以上的对二氯苯产品,收率可达75％－90％。     

The Preparation of Rapeseed Lecithin with High Phosphatidylcholine Content

The raw commercial rapeseed lecithin free of erucic acid and glucosinolate (00-type) was purified by deoiling with acetone and extracting with ethanol. The increasing of phosphatidylcholine (PC) content (from 50 to 70–80%) in obtained rapeseed lecithin extract was performed. It was done by column chromatographic fractionation using a low silica gel–lecithin extract ratio about 2:1 and the various temperatures up to 60°C. The fractions were eluted with 95% ethanol. Effect of rapeseed lecithin column fractionation temperatures is significant and the better purification quality in the higher temperatures was observed. Based on performed investigations it could be summarized that the low silica gel–lecithin extract ratio (2:1) allows to obtain rapeseed lecithin with above 80% content of PC and the best results for temperature 60°C were observed.     

用于分离DMF/H2O体系的Me-silicalite-1渗透汽化分子筛膜的制备

采用二次生长法制备了用于渗透汽化分离DMF/H2O体系的杂原子取代Me-silicalite-1/α-Al2O3(Me=Co、Fe)分子筛复合膜,通过X射线衍射(XRD)、扫描电镜(SEM)、傅里叶红外光谱(FT-IR)和紫外漫反射(UV-Vis)等方法对分子筛膜进行表征,结果表明金属离子进入分子筛骨架。渗透汽化实验显示,金属离子掺杂的silicalite-1/α-Al2O3分子筛复合膜,具有较好的分离性能且优先透过有机胺,有利于工业中DMF溶剂的回收和利用。随着操作温度升高,分离因子减小,渗透通量增加。40℃分离质量分数为5%的DMF/H2O混合液时,Co-silicalite-1/α-Al2O3分子筛膜和Fe-silicalite-1/α-Al2O3分子筛膜的分离因子分别为4.4和2.9,渗透通量分别为0.66和0.84 kg·m-2·h-1。     

A Two-Cycle Process for Enhanced Actinide Separation from Radioactive Liquid Wastes

Abstract

A two-cycle process using O°CMPO and HDEHP as extractants to achieve an alpha decontamination factor of HLLW greater than 10³ together with a reduction of the lanthanides/americium weight ratio by a factor of about 200 is considered. Experimentally measured distribution ratios have been employed as input data of a suitable computer code to define operating conditions and M/S stage numbers of a process flow-sheet able to meet the above-mentioned objectives.     

A Separation Factor Method for the Analysis of Ideal Binary Mixtures in Gas-Solid Adsorption

Abstract

A correlation formula based on the separation factor is proposed for the mixture concentration in the adsorbed phase of an ideal binary solution in gas-solid adsorption. This formula is shown to apply to two binary systems (viz., 1,3-butadiene and n-butane on cross-linked polystyrene at 25°C, and acetylene and ethane on activated carbon at 25°C) with similar molecular and thermodynamic properties in the two components for each system. Comparison between the calculated and experimental values of the separation factor showed that the assumption of an ideal mixture is justified for each of these two binary systems. Mixture isotherms for the two ideal binary systems are calculated by the proposed correlation formula from the corresponding single-component isotherms. Good agreement between the calculated and experimental mixture isotherm data confirms that a binary system of two components with similar molecular properties (viz., molecular weight, normal boiling point, vapor pressure, number of carbon atoms in molecules, etc.) tends to form an ideal mixture (i.e., one with a constant separation factor).     

Membrane Pervaporation: Separation of Organic/aqueous Mixtures

Abstract

The recovery of water-laden solvents by membrane pervaporation has become an industrially-accepted practice. A review of the technology is presented, along with discussion of the potential for removal of organics from water.     

微米与亚微米级的液固与气固混合物的一种新型分离技术

微米与亚微米级的液固与气固混合物的高效分离非常困难。目前工业生产上普遍使用的各种传统分离技术,其分离效率均不高。本文给出一种新的分离技术——高分子烧结精密微孔过滤技术(由烧结微孔过滤介质、精密微孔过滤机、辅助装置及不同的应用方法组成)能对这些混合物进行高效分离,能得到干的滤饼。除了过滤效率高外,其操作还非常简便,占地面积较小,动力消耗较少,操作成本与投资费均较低。该技术已在国内许多工业生产与废水处理中获得广泛应用。     

Thermal Diffusion Factor for Carbon Tetrachloride-Cyclohexane and Benzene-n-Heptane Mixtures from Thermogravitational Column Separation

Abstract

Measurements of the separation of liquid mixtures of n-heptane/benzene and carbon tetrachloride/cyclohexane in a thermogravitational column are reported. The results show that thermal diffusion columns of little mechanical precision can furnish suitable thermal diffusion factors when the diffusion coefficient, viscosity, density, and compressibility factor for the mixture are known.     

烯丙基蔗糖的制备

以蔗糖为原料,NaOH为活化剂对蔗糖进行活化预处理,烯丙基氯为醚化试剂,制备了烯丙基蔗糖(AS)。研究了活化碱剂,预处理和反应温度及时间对产品收率和取代度的影响。结果表明:在n(烯丙基氯)∶n(蔗糖)∶n(NaOH)=10∶1∶10,前处理温度60℃,前处理时间7 h,反应温度50℃,反应6 h条件下,所制备的AS的取代度为6.65,收率为91%,用FTIR、MS对其结构进行了表征,合成成本大大降低。     

乙醇提取鸭蛋黄卵磷脂的工艺研究

采用正交实验和单因素实验方法,考察了提取温度、乙醇浓度、提取时间、料液比对鸭蛋卵磷脂提取率的影响。结果表明：在提取温度30℃、乙醇浓度92%、提取时间60min且料液比为1：5的条件下,从鸭蛋黄中提取卵磷脂的得率达9.92%。     

乙撑亚胺法合成牛磺酸的工艺研究

研究了乙撑亚胺法合成牛磺酸的方法：以乙醇胺碱性条件合成乙撑亚胺。乙醇胺硫酸酯与氢氧化钠配比化学计量比为1：1．20最佳,反应温度110℃～120℃;起始的乙醇胺硫酸酯与亚硫酸氢铵配比为1：1．15,乙撑亚胺与亚硫酸氢铵开环反应控制温度在40℃以下,时间为1～1．5h,pH为8左右。     

The Separative Bioreactor: A Continuous Separation Process for the Simultaneous Production and Direct Capture of Organic Acids

Abstract

The replacement of petrochemicals with biobased chemicals requires efficient bioprocesses, biocatalysis, and product recovery. Biocatalysis (e.g., enzyme conversion and fermentation) offers an attractive alternative to chemical processing because biocatalysts utilize renewable feedstocks under benign reaction conditions. One class of chemical products that could be produced in large volumes by biocatalysis is organic acids. However, biocatalytic reactions to produce organic acids typically result in only dilute concentrations of the product because of product inhibition and acidification that drives the reaction pH outside of the optimal range for the biocatalyst. Buffering or neutralization results in formation of the acid salt rather than the acid, which requires further processing to recover the free acid product.

To address these barriers to biocatalytic organic acid production, we developed the “separative bioreactor” based on resin wafer electrodeionization, which is an electrodeionization platform that uses resin wafers fabricated from ion exchange resins. The separative bioreactor simultaneously separates the organic acid from the biocatalyst as it is produced, thus it avoids product inhibition enhancing reaction rates. In addition, the separative bioreactor recovers the product in its acid form to avoid neutralization. The instantaneous separation of acid upon formation in the separative bioreactor is one of the first truly one‐step systems for producing organic acids.

The separative bioreactor was demonstrated with two systems. In the first demonstration, the enzyme glucose fructose oxidoreductase (GFOR) was immobilized in the reactor and later regenerated in situ. GFOR produced gluconic acid (in its acid form) continuously for 7 days with production rates up to 1000 mg/L/hr at >99% product recovery and GFOR reactivity >30 mg gluconic acid/mg GFOR/hour. In the second demonstration, the E. coli strain CSM1 produced lactic acid for up to 24 hours with a productivity of >200 mg/L/hr and almost 100% product recovery.     

A Dip-Coating Process for the Preparation of PZT Microtubes

PZT microtubes have been fabricated by dip coating of aqueous PZT powder slurry on vermicelli, followed by burnout of the vermicelli and sintering. The water-absorbing character of the vermicelli made a thin layer of PZT slurry to gel on its surface during dip coating. Thickness of the gel on the surface of the vermicelli depends on the dipping time. The green PZT layer thickness in the range of 140–190 μm could be achieved for a dipping time of 30–120 s. Microtubes having an inner diameter of nearly 500 μm with wall thickness in the range of 120–160 μm could be prepared by this process.     

吸附法脱除烷烃中少量芳烃工业可行性分析

在实验研究烷烃中少量芳烃的吸附动态过程的基础上,确定该吸附净化过程的吸附一再生条件,探讨该过程实现的可行性,得到如下结论：从技术性能和技术经济这两个指标出发,对脱除循环烷烃中的少量芳烃的吸附分离过程,用固定床吸附过程来实现比用模拟移动床吸附过程来实现更具可行性,吸附法脱除循环烷烃中的少量芳烃具有设备投资少,能耗低的特点,有可能成为一种替代现行脱除少量芳烃的工艺方法,这些结果为在直链烷基苯的生产过程中,降低循环烷烃中芳构化物的含量,实现延长脱氢催化剂的寿命,提高烷基苯的产量提供了技术基础。     

盐效分离过程中选择盐的方法

从盐在纯溶剂中的溶解度、单个盐与溶剂分子间相互作用强度两方面进行考虑,提出盐对溶剂的总作用的概念,并用盐对二溶剂总作用的差作为选择盐效分离用盐的标准,针对某一物系,对各种盐进行比较筛选。通过实例证实该法为工业选盐的好方法。