真空膜蒸馏过程膜参数模拟计算

为了研究膜材料对透过通量的影响,文章建立了真空膜蒸馏过程的微观传热传质模型,并利用该模型对文献中的实验数据进行了模拟,得到了比较满意的结果。进而对不同条件下膜的长度、厚度、内径以及曲折因子、传质系数进行了模拟计算,并讨论了不同膜参数对膜透过通量的影响,为真空膜蒸馏过程中膜材料的选取及合理利用提供一定的理论依据。     

复合中空纤维超滤膜的研制

本文就复合中空纤维超滤膜的制备工艺和成膜条件对膜性能影响进行了系统的研究，实验表明，对外压式中空纤维膜，内凝固液条件的改变，主要影响复合膜的内致密层，进而影响膜的透过通量，但对膜的截留孔径无影响，随空中行走距离增大，膜的透过通量减小，截留孔径增大。另外，通过基膜的选定与内凝固液的调节，复合中空纤维膜的分离孔径主要取决于复合层膜，即在适宜的条件下，基膜不影响复合膜的分离孔径，同时也不决定复合中空纤维     

富氮膜分离过程的理论分析和实验研究

本文对用中空纤维膜从空气中富集氮气的过程进行研究,较好地揭示了过程中各参数及膜性能与分离结果的关系.改变实验条件可得到浓度为85%～99.6%的富氮气体,回收率为78%～23%.实验对理论模型进行了验证,结果表明,在实验浓度范围内采用柱塞流逆流模型和全混柱塞流模型的计算值与实验值基本吻合,模型可以满足工业模拟和设计要求.     

中空纤维膜萃取苯酚的传质及流动特性

以体积分数为30％的磷酸三丁酯＋煤油－水为实验体系，研究了中、高装填密度的中空纤维膜萃取处理苯酚衡溶液的传质效果和传质特性以及膜器壳程流动状况。实验结果表明，中空纤维膜萃取可以高效去除水中的苯酚，萃取率最高可达到99．9％。比较了总传质系数的实验值与多个传质系数关联式的预测值之间的偏差，发现从中、高装填密度膜器得到的传质关联式偏差较小，而从低装填密度膜器得到的传质关联式偏差较大。通过测量膜器壳程流动的停留时间分布曲线，证实了偏差是由于中、高装填密度的膜器壳程流动的复杂性造成的。     

聚丙烯酰胺固体凝胶膜中甲醇透过性能研究

采用膜扩散法，由示差折光仪在线测试了聚丙烯酰胺(PAAM)固体凝胶膜室温下甲醇透过系数。实验结果表明，随凝胶浓度的增加，PAAM固体凝胶膜的甲醇透过系数呈下降趋势；但在凝胶浓度一定的情况下，随凝胶中文链度的增加，PAAM固体凝胶膜的甲醇透过系数出现极小值。因此，PAAM固体凝胶膜在掺杂导电成分后可于直接甲醇燃料电池(DMFC)中作为阻醇电解质膜使用。     

聚吡咙膜的气体透过性能及应用

论述新型芳族含氮杂环聚吡咙膜的气体透过性能和应用，并与聚酰亚胺(PI)膜的气体分离性能进行比较。揭示出聚吡咙膜的扩散系数与气体分子有效直径之间及溶解系数和临界温度之间呈直线关系，指出气体在聚吡咙膜中的透过主要受扩散因素控制。与类似结构的PI膜相比，聚吡咙膜具有更优异的氧氮分离性能、CO2/CH4分离性能和氢氮分离性能，其透过系数和选择分离系数均高于PI膜，是一类很有发展潜力的聚合物膜材料。     

炭膜制备及其气体透过性

以炭粉为原料，加粘结剂成型制备炭膜并对其气体透过性进行了研究，考察了粘结剂用量，炭化等因素对炭膜的气体透过速率和气体组份理想分离系数的影响，气体透过膜孔的扩散为粘性流和努森扩散。     

膜蒸馏跨膜传质过程的新模型--TPKPT

以纯水为介质,用直接接触式膜蒸馏测定了材料或性能参数不同的三种孔疏水膜在不同温度下的渗透通量。根据测量结果计算出了各种膜在不同温度下的渗透系数,发现渗透系数均随着温度的升高而升高;这一结果说明Poiseuille流动在跨膜传质中起着非常重要的作用。据此提出了Knudsen扩散－Poiseuille流动两参数跨膜传质模型,即TPKPT模型。用此模型拟合实验数据,得到了三种实验用膜的模型参数。用这些模型参数计算膜在不同温度下的渗透系数,其值与实验测量值吻合较好,说明TPKPT模型能较好地描述膜蒸馏的跨膜传质过程。     

阳离子交换膜对氯离子透过率的研究

在电渗析过程中，离子交换膜隔绝反离子并使同离子通过，但实际使用过程中并非完全隔离，在电渗析过程中仍有部分反离子透过膜，限制了离子交换膜的应用效果，尤其是在氯离子环境中阳离子交换膜在实际使用过程中会有氯离子透过阳膜到达产物与阳极，产生的氯气污染环境、加剧膜的氧化，降低了膜的透过性，形成了恶性循环，为探究电渗析过程中离子交换膜对氯离子的截留效果，本文开展了阳离子交换膜对氯离子透过率的相关研究，研究表明，阳离子交换膜的种类对阳离子交换膜对氯离子的透过率有重要影响；电流密度和原料初始浓度的增加会导致阳离子交换膜对氯离子的透过率增加，实际生产中为减少产物中氯离子的含量，同时保证较高的生产效率，需要综合考量各方面的影响因素以确定最佳的工艺条件。     

稳定膜透水率的新方法—恒流控制

本文从理论上分析了减轻膜污染、提高膜产水量的有效方法之一是降低的平均操作压力,并在此基础上提出了恒流控制的操作方式,即保证在一个周期内膜组件的透过液流量恒定,以及实现恒流控制的三种方法。本研究还通过实验在分置式膜生物反应器中比较了相同条件下恒流控制与传统的恒压控制时膜的产水量,结果表明前者比后者提高了12．6％。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.     

Highly moisture-proof polysilsesquioxane coating prepared via facile sol-gel process

A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by ¹H MAS NMR. For direct comparison purposes, an SiO₂ coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N₂ absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.