芳烃/脂肪烃混合物分离渗透汽化膜的研究进展

芳烃/脂肪烃混合物的分离是化学工业中的重要过程,但是由于其物理和化学性质非常相似,采用传统方法分离困难。与传统的分离技术(萃取、蒸馏)相比,渗透汽化技术在经济、节能和环保方面具有很大的发展前景。本文综述了用于芳烃/脂肪烃混合物渗透汽化分离的渗透汽化膜的研究进展,对渗透汽化技术用于芳烃/脂肪烃混合物的研究前景进行了展望。     

芳烃/脂肪烃混合物分离渗透汽化膜的研究进展

芳烃/脂肪烃混合物的分离是化学工业中的重要过程,但是由于其物理和化学性质非常相似,采用传统方法分离困难。与传统的分离技术(萃取、蒸馏)相比,渗透汽化技术在经济、节能和环保方面具有很大的发展前景。本文综述了用于芳烃/脂肪烃混合物渗透汽化分离的渗透汽化膜的研究进展,对渗透汽化技术用于芳烃/脂肪烃混合物的研究前景进行了展望。     

芳烃优先透过的渗透汽化复合膜的制备及分离性能研究

采用紫外光接枝填充聚合技术,以非对称聚丙烯腈(PAN)超滤膜为底膜,聚乙二醇甲醚甲基丙烯酸酯(MePEO300MA)为大分子单体,制备了芳烃优先透过的渗透汽化复合膜。考察了单体浓度和紫外光照射反应时间对复合膜甲苯/正庚烷渗透汽化分离性能的影响,并对复合膜降低石脑油芳烃含量,优化乙烯裂解原料进行了初步探索。研究结果表明,复合膜对甲苯质量分数为20%的甲苯/正庚烷混合物(80℃)的分离系数达到5.6,渗透通量为2.47 kg/(m2.h);当切割比为20%时,石脑油的芳烃质量分数由7.52%降至4.11%,降低了45%,初步说明渗透汽化复合膜在降低石脑油的芳烃含量,优化乙烯裂解原料方面的应用前景。     

渗透汽化膜技术及其在溶剂分离领域的应用

渗透汽化膜技术是一种高效节能、绿色环保的新型膜分离技术,与传统分离技术相比优势显著,使该技术成为溶剂分离领域研究的焦点。简述了渗透汽化膜技术的基本原理和工艺流程,介绍了渗透汽化膜技术在有机溶剂/水体系、有机溶剂/有机溶剂体系分离的研究应用现状,展望了渗透汽化膜分离技术的研究应用前景。     

渗透汽化分离乙酸的研究进展

渗透汽化作为一种新型的膜分离技术应用于乙酸的分离,可以优先透水或乙酸。特别是应用在发酵法制备乙酸等低酸含量溶液的分离中,可以优先透酸制备高纯度的乙酸,具有显著的优势。本文综述了渗透汽化技术在分离纯化乙酸中所涉及的膜材料、耦合工艺及其应用现状,并展望了其发展趋势。     

渗透汽化膜分离技术最新研究进展

综述了渗透汽化膜材料的制备以及其应用于有机物脱水,有机物回收,有机物/有机物的分离的最新研究进展,由于渗透汽化具有操作简单、占地面积小、能力消耗低等特点,所以,渗透汽化技术在石油、化工、食品等行业中应用广泛,但是,渗透汽化技术也存在着膜污染、寿命短等缺点,所以,开发具有通量大、分离性能好以及寿命长的膜材料将是未来研究的重点。     

渗透汽化在醇/水分离中的应用

一种新型的膜分离技术即渗透汽化技术逐渐在食品工业中得到应用.该文简要介绍了渗透汽化原理和渗透汽化分离膜,着重论述了渗透汽化技术在食品工业中醇/水分离方面的应用研究.     

神府煤石油醚萃取物组成及萃取过程分析

采用自行研制的萃取系统对神府煤进行了石油醚溶剂萃取,并结合GC/MS技术对萃取物进行了定性和定量分析,讨论了萃取物的化学组成及其萃取过程.结果显示,神府煤石油醚萃取物的GC/MS可测组分主要由脂肪烃、芳烃及含氧杂原子化合物组成,其中含氧化合物相对含量达到72%;各次循环萃取量经历了从低到高、再从高到低的过程;各分子化合物在溶剂中的溶解析出规律有较大差异.     

丁醇发酵耦合渗透气化分离技术研究进展

对国内外丁醇发酵过程中常用的发酵技术、渗透汽化膜材料的选择、发酵耦合渗透汽化分离技术的研究进展进行了综述,并分析了渗透汽化技术目前存在的问题及今后的发展前景。     

离子液体液液萃取分离正辛烷/邻二甲苯

将直馏石脑油分离为脂肪烃和芳烃有助于实现石脑油资源的优化利用,溶剂萃取是芳烃/脂肪烃分离的重要途径,萃取剂的设计与优选对萃取过程至关重要。实验探究了多种离子液体对正辛烷/邻二甲苯混合物萃取分离的效果,以萃取选择性、分配系数和萃取性能指数作为评价指标优选出1-丁基-2,3-二甲基咪唑四氯化铁([Bm₂im][FeCl₄])萃取剂。对于中低浓度芳烃体系(<33%),在30℃、溶剂质量比为4时,邻二甲苯萃取选择性在45以上,分配系数在0.38~0.40,萃取性能指数在18以上,单次萃取脱芳率可达60%以上。相比传统的环丁砜萃取剂,[Bm₂im][FeCl₄]萃取剂可以使体系具有更大的两相区,易于正辛烷/邻二甲苯的分离。利用量子化学软件探究[Bm₂im][FeCl₄]与正辛烷/邻二甲苯的弱相互作用,并计算其结合能,解释离子液体高选择性萃取邻二甲苯的原因。     

Membrane materials in the pervaporation separation of aromatic/aliphatic hydrocarbon mixtures—A review

The separation of aromatic/aliphatic hydrocarbon mixtures is a significant process in chemical industry,but challenged in some cases.Compared with conventional separation technologies,pervaporation is quite promising in terms of its economical,energy-saving,and eco-ffiendly advantages.However,this technique has not been used in industry for separating aromatic/aliphatic mixtures yet.One of the main reasons is that the separation performance of existed pervaporation membranes is unsatisfactory.Membrane material is an important factor that affects the separation performance.This review provides an overview on the advances in studying membrane materials for the pervaporation separation of aromatic/aliphatic mixtures over the past decade.Explored pristine polymers and their hybrid materials (as hybrid membranes) are summarized to highlight their nature and separation performance.We anticipate that this review could provide some guidance in the development of new materials for the aromatic/aliphatic pervaporation separation.     

Poly(Vinyl Alcohol)/Graphene Oxide Mixed Matrix Membranes for Pervaporation of Toluene and Isooctane

Poly(vinyl alcohol)/graphene oxide mixed matrix membranes have been prepared and applied for the pervaporation of isooctane (aliphatic) and toluene (aromatic) mixtures. Characteristics of the membranes such as crystallinity, morphology, and swelling have been investigated, and the results have been used to describe pervaporation performance. Experimental tests evidenced that incorporation of low content of graphene oxide nanoplates (0.5?wt%) in poly(vinyl alcohol) increases affinity of the membrane to aromatics by S and π bonds and selectivity increase to about four times. Moreover, interaction of graphene oxide with toluene results in increasing of swelling and decreasing of permeation flux.     

Pervaporation of Water/Ethanol Mixtures by an Aromatic Polyetherimide Membrane

Abstract

The pervaporation of water/ethanol mixtures through an aromatic polyetherimide membrane was attempted. The membrane was laboratory prepared using the solution casting technique. The sorption characteristics in relation to pervaporation were also studied. It was found that the preferential sorption was altered when the liquid composition was changed, whereas the water component permeated through the membrane preferentially over the whole range of feed mixture compositions. The experimental results were analyzed in terms of sorption ratio and permeation ratio to characterize nonideality of sorption and pervaporation. The effects of some operating parameters, including temperature, feed concentration, and permeate pressure, on the pervaporation performance were also investigated.     

Permselectivities of 2,2′‐dimethyl‐4,4′‐bis(aminophenoxyl)biphenyl diphenyl methane–based aromatic polyamide membranes for aqueous alcohol mixtures in pervaporation and evapomeation

The separation of aqueous alcohol mixtures was carried out by use of a series of novel aromatic polyamide membranes. The aromatic polyamides were prepared by the direct polycondensation of 2,2′‐dimethyl‐4,4′‐bis(aminophenoxyl)biphenyl (DBAPB) with various aromatic diacids, such as terephthalic acid (TPAc), 5‐tert‐butylisophthalic acid (TBPAc), and 4,4′‐hexafluoroisopropylidenedibenzoic acid (FDAc). The pervaporation and evapomeation performance of these novel aromatic polyamide membranes for dehydrating aqueous alcohol solution were investigated. The solubility of ethanol in the aromatic polyamide membranes is higher than that of water, but the diffusivity of water through the membrane is higher than that of ethanol. The effect of diffusion selectivity on the membrane separation performances plays an important role in the evapomeation process. Compared with pervaporation, evapomeation effectively increases the permselectivity of water. Moreover, the effect of aromatic diacids on the polymer chain packing density, pervaporation, and evapomeation performance were investigated. It was found that the permeation rate could be increased by introduction of a bulky group into the polymer backbone. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2688–2697, 2003     

Poly(Trimethylsilylpropyne) Utility as a Polymeric Absorbent for Removal of Trace Organics from Air and Water Sources

Abstract

Poly(trimethylsilylpropyne), PTMSP, is well known to exhibit the highest permeability for gas and vapors of all dense polymeric systems. The high free volume observed yields extremely high diffusion coefficients for penetrating species. These properties have yielded interest for various gas and pervaporation membrane separation processes. It has been found that PTMSP also exhibits unique characteristics as a polymeric absorbent for removal of trace organics from air and water sources. The distribution coefficient for organics between the PTMSP phase and the water phase is extremely high for aliphatic, aromatic, and chlorinated hydrocarbons. In fact, PTMSP approaches activated carbon adsorbents in efficiency (much closer than other polymeric species). The removal of organics from PTMSP proceeds easier than activated carbon, and applications involving simple regeneration of a fixed bed may indeed be possible.     

Concentration by pervaporation of aroma compounds from Fucus serratus

The aromatic compositions of a marine alga (Fucus serratus) and its maceration were determined. Sixteen major volatile compounds were selected as being representative of algal aroma components. Pervaporation performance was investigated using a model multicomponent solution and low aroma compound fluxes were obtained. Interesting selectivities were calculated showing the concentration potential of pervaporation. Comparison with maceration pervaporation was made and showed similar selectivity values. Finally, the sensorial quality of the maceration pervaporate was evaluated regarding the operating parameters of pervaporation. The permeate pressure had a statistically significant effect upon aromatic quality. © 2000 Society of Chemical Industry     

Effect of aromatic and aliphatic amines as curing agents in sulfone epoxy monomer curing process

The kinetics of the curing of sulfone epoxy (SEP) monomers using aromatic and aliphatic amine curing agents was studied via differential scanning calorimetry (DSC). SEP curing is a two-stage process involving SEP/electron donation and electron donation to either aliphatic or aromatic curing agents. The SEP/electron donation curing process occurred readily since semi-electron-withdrawing curing agents are induced by nucleophilic substitution in the first stage. In the second stage, SEP is cured by the semi-electron-withdrawing curing agents. The kinetic parameters of the curing process were determined using a conversional method derived from Ozawa’s and Kissinger’s methods, which are typically used for kinetic analysis of data for thermal treatments. The higher melting points and steric bulk of the aromatic curing agents resulted in higher curing activation energies than for the aliphatic curing agents. The aliphatic curing agents also increased the activation energy of the curing process due to their electron-withdrawing and cross-linking properties as well as the viscosity of the epoxy/amine curing system. Cured SEP/aromatic curing agent materials possessed higher glass transition temperatures than cured SEP/aliphatic curing agent materials.     

Effect of functionalization on dispersion of POSS‐silicone rubber nanocomposites

The nanocomposite of PDMS using functionalized fumed silica and nonreactive POSS as fillers were prepared by blend method in a planetary mixer. Fumed silica was functionalized by aliphatic and aromatic groups to study the filler–filler interactions with the aliphatic and aromatic POSS fillers and consequently their influence on the properties in the PDMS matrix. Transmission electron microscope (TEM) showed a good dispersion in the systems having the silica and POSS fillers with similar modifications. However, aliphatic and aromatic filler combinations showed more aggregated structures. Moreover, aliphatic POSS despite of good dispersion at higher loadings, act as lubricant, which is attributed to the disturbance in the PDMS‐ silica filler interaction and also the filler–filler interaction within fumed silica. There is a decrease in complex viscosity with the functionalization of fumed silica and with the aromatic/aliphatic POSS fillers. The thermal stability of aromatic functionalized fillers improves owing to the thermally stable phenyl groups. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Maintaining hydrostatic conditions during solidification of polymers in a high-pressure dilatometer

Amorphous polyarylates derived from 12–50 mol % of a t-butyl-substituted diacid, e.g., 5-t-butylisophthalic acid, exhibit miscibility with the amorphous phase of polyamides having aromatic and aliphatic character. Equally critical to blend miscibility is the aliphatic/aromatic carbon atom ratio (exclusive of the amide functionality) of the polyamide. An aliphatic/aromatic carbon atom ratio (α) greater than 1.4 but less than 2.5 is necessary. © 1992 John Wiley & Sons, Inc.