PDMS/PEI膜渗透汽化分离正丁醇/乙醇/水的性能及渗透通量关联模型研究

采用聚二甲基硅氧烷/聚醚酰亚胺(PDMS/PEI)膜渗透汽化分离正丁醇/乙醇/水体系,考察进料温度、进料组成等条件对膜渗透汽化分离性能的影响;采用Arrhenius型半经验渗透通量关联模型描述PDMS-PEI膜分离正丁醇/乙醇/水体系膜通量变化。结果表明,当原料液中正丁醇质量分数分别为4.0%、4.5%和5.0%时,正丁醇/乙醇/水三元体系中正丁醇渗透通量分别至少提高14.2%、17.7%和23.4%。渗透通量关联模型能较好地描述PDMS-PEI膜分离正丁醇/乙醇/水体系膜渗透通量变化。     

水热合成高性能丝光沸石膜及其在四氢呋喃脱水中的应用

在不添加模板剂的情况下,通过二次生长合成法在多孔α-Al_2O_3载体外表面制备丝光沸石膜。当结晶温度为160℃,结晶时间为24 h时,丝光沸石膜的渗透通量和分离因子同时达到最大值,分别为0.125 kg/(m~2·h)和840。在水/异丙醇混合物中测试了沸石膜的渗透汽化能力;通过扫描电子显微镜和X射线衍射表征膜的晶体结构和形貌。将得到的丝光沸石膜用于四氢呋喃脱水,通过研究渗透汽化温度和进料浓度对脱水过程的影响,发现丝光沸石膜具有良好的分离性能。     

两步变温水热合成制备纯硅分子筛膜及其渗透性能

采用两步变温水热法在多孔不锈钢载体管上合成了Silicalite-1沸石膜,对合成的Silicalite-1膜进行了X射线衍射和扫描电镜及单成分气体渗透表征,并将其应用于渗透脱除水中乙醇,考察了晶化温度、合成液组成及合成次数对渗透性能的影响. 结果表明,用两步变温合成法可得到高性能的纯硅沸石膜,水/硅(摩尔比)为80且第二步晶化温度为165℃的条件下,只需经一次合成,可获得对乙醇水溶液具有高分离性能的膜,在60℃、乙醇浓度为4.8%(w)时,膜的通量为1.25 kg/(m2×h),分离系数为36.2,但经再次合成后,通量和分离系数均劣化. 水/硅(摩尔比)为225且第二步晶化温度为150℃条件下,经过再次合成,通量和分离系数均得到大大提高,在60℃和乙醇浓度为4.52%(w)时,通量和分离系数分别高达2.8 kg/(m2×h)和34.3,在如此高的分离系数下该通量达到了国内外报道的最高值.     

有机硅烷改性PDMS/Silicalite渗透汽化杂化膜制备及其分离性能

采用硅烷偶联剂对全硅沸石Silicalite-1进行表面改性,以聚二甲基硅氧烷(PDMS)为基体,制备了渗透汽化PDMS/Silicalite杂化膜. 用FT-IR, TGA等对改性的效果和杂化膜的热稳定性能进行了表征,并以低浓度乙醇/水体系为研究对象,以渗透通量和分离因子为评价指标,考察了料液组成、进料温度、循环流速、膜下游侧真空度等因素对改性杂化膜分离性能的影响. 结果表明,硅烷改性沸石所制杂化膜对低浓度乙醇/水体系的分离因子比空白膜和未改性杂化膜分别提高136%和45%. 随料液中乙醇浓度从5%增加到69%,膜分离因子从22降低到7,而其他因素对膜的选择性影响较小.     

ZSM-5沸石膜用于生物油的脱水分离及其再生过程研究

在水热条件下通过无模板剂法合成了连续的ZSM-5沸石膜,并将其用于生物油的渗透汽化以进行高效脱水分离。ZSM-5沸石膜在强酸性、多组分的生物油体系中保持了很好的化学稳定性和优异的分离选择性,但在分离过程中面临着较强的膜污染问题,导致了膜通量的大幅下降。ZSM-5沸石膜的再生研究表明,膜的渗透通量随着再生温度的升高而逐渐提高。当再生温度为220℃时,ZSM-5沸石膜的渗透通量可以恢复至初始的88%。再生的机理研究表明,ZSM-5沸石膜中大量的晶内孔在生物油体系中极易被污染,从而导致渗透通量迅速下降;而相对较大的晶间孔却难以被完全堵塞,水分子在被污染的ZSM-5沸石膜中主要通过晶间孔进行渗透。上述结果表明,通过合理调控ZSM-5沸石膜的晶间孔的数量和尺寸大小可有效提升ZSM-5沸石膜在生物油中的渗透汽化脱水分离性能。     

氯硅烷改性ZSM-5填充PDMS复合膜渗透汽化透醇性能

采用十二烷基三氯硅烷对ZSM-5型沸石进行表面修饰改性,并用FT-IR,CA和BET等对改性前后的沸石特征进行分析表征,改性后的沸石表面憎水性增强,比表面积有所下降.将改性后的沸石填充到硅橡胶中制备出了PDMS/ZSM-5杂化膜,并将其用于乙醇/水稀溶液的分离,在40℃下,进料乙醇浓度为5%(质量分数)时,其分离因子最高可达15.8,渗透通量为202.95g/(m~2·h).     

分离有机水溶液的聚离子复合膜（Ⅰ）

进行了ＰＡＮ多孔膜的表面水解改性及聚离子复合改性，探讨了水解反应温度、碱液浓度、水解时间等对膜的渗透汽化分离性能的影响。结果表明，ＰＡＮ超滤膜经水解和聚离子复合改性后，可制成性能优良的渗透汽化膜。用于对乙醇水溶液进行渗透汽化分离，当进料浓度为９０％（ｗｔ），进料温度为６４℃时，渗透通量为１２００ｇ／ｍ２．ｈ左右，分离因子为２４０。     

分离有机水溶液的聚离子复合膜（I）

进行了ＰＡＮ多孔膜的表面水解改性及聚离子复合改性，探讨了水解反应温度、碱液浓度１水解时间等对膜的渗透汽化分离性能的影响。结果表明，ＰＡＮ超滤膜经水解和聚离了复合改性后，可制成性能优良的渗透汽化膜，用于对乙醇水溶液进行渗透汽化分离，当进料浓度为９０％（ｗｔ），进料温度为６４℃时，渗透通量为１２００ｇ／ｍ＾２，ｈ左右，分离因子为２４０。     

有机硅烷改性ZSM-5/BPPO非对称膜制备及其渗透汽化性能

以硅烷改性ZSM-5分子筛为填充剂,采用沉浸凝胶相转化法制备了ZSM-5/BPPO非对称膜. 结果表明,分子筛在BPPO膜中分散均匀,填充分子筛后膜表面粗糙度增大、疏水性增强. 以低浓度乙醇-水体系为研究对象,考察了分子筛填充量、进料液浓度及进料液温度对ZSM-5/BPPO膜渗透汽化分离性能的影响. 结果表明,随乙醇浓度增大,ZSM-5/BPPO膜的分离因子减小,渗透通量增大;随进料液温度升高,ZSM-5/BPPO膜的分离因子及渗透通量均增大;在60℃、分子筛填充量为0.3%(w)时,ZSM-5/BPPO膜对5%(w)乙醇-水体系的分离因子高达18.49,渗透通量为529.69 g/(m2×h). ZSM-5/BPPO膜对不同醇-水体系的分离结果表明,醇类分子量越大,膜分离性能越好.     

沸石分子筛膜的合成与应用

综述了沸石分子筛膜的合成方法和应用。介绍了制备沸石分子筛膜最常州的水热合成法，包括晶种法和原位合成法，以及沸石分子筛膜在气体分离、渗透汽化和膜反应器中的应用。重点阐述了被除数广泛研究的MFI型分子筛膜的制备方法与应用。详细讨沦了多孔支撑体、晶体、水热合成条件以及合成液组成等因素对晶体生长和膜的形态以及对MFI型分子筛膜分离性能的影响，     

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.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.