醋酸甲酯-甲醇-水体系的盐效应

在20℃的条件下研究了加入氯化钙对醋酸甲酯-甲醇-水体系产生的盐效应。实验结果表明,随着初始水相中氯化钙质量分数的增加,两相区逐渐扩大,醋酸甲酯在水相的溶解度和水在有机相中的溶解度均有所降低。在有机相中甲醇质量分数一定的条件下,随着初始水相中氯化钙质量分数的增加,甲醇在有机相和水相间的分配系数减小,甲醇的选择性系数而增大。这些结论表明,采用加盐萃取对醋酸甲酯和甲醇进行分离十分有利。对该含盐体系的液—液平衡数据采用Eisen-Joffe方程进行了关联,关联值与实验值的平均相对偏差为4 08%。     

定标粒子理论在加盐萃取分离醋酸甲酯的应用

采用选择性溶剂化模型和定标粒子理论计算了8种盐类萃取剂在醋酸甲酯-甲醇-水三元体系中的标准摩尔溶剂化自由能,引入盐的溶解参数进行修正,并结合萃取分离实验进行验证,结果表明,随着盐的标准摩尔溶剂化自由能绝对值的增大,有机相中酯的质量分数呈线性增大,而有机相中水的质量分数则呈线性降低。静电相互作用力是影响加盐萃取效果的主要原因,盐与水(或醇)分子之间的静电自由能绝对值越大,盐对酯的萃取效果越好。采用标准摩尔溶剂化自由能的计算值可从理论上定量选择适宜的盐类作为萃取剂。     

定标粒子理论在加盐萃取分离醋酸丙酯-丙醇-水中的应用

采用选择性溶剂化模型和定标粒子理论计算了七种盐类萃取剂在醋酸正丙酯-正丙醇-水三元体系中的标准摩尔溶剂化自由能,结合萃取分离实验进行验证,结果表明,随着盐的标准摩尔溶剂化自由能绝对值的增大,有机相中酯的质量分数呈线性增大,而有机相中水的质量分数则呈线性降低.静电相互作用力是影响加盐萃取效果的主要原因,盐与水(或醇)分子之间的静电自由能绝对值越大,盐对酯的萃取效果越好,采用标准摩尔溶剂化自由能的计算值可从理论上定性选择适宜的盐类作为萃取剂.     

多级错流萃取分离丙酸甲酯-甲醇-水体系的模拟及实验研究

设计了丙酸甲酯-甲醇-水体系错流萃取分离工艺,通过实验选择了丙三醇-水的复合溶剂作为分离丙酸甲酯-甲醇-水体系的最佳萃取剂。以UNIQUAC方程为计算活度系数模型,采用色谱法测定了甲醇在丙三醇中的无限稀释活度系数,并运用单参数法计算了UNIQUAC方程中的相互作用参数。采用相分配系数和物料平衡方程对整个错流萃取过程进行了模拟计算。实验及模拟结果表明:当静置时间为20min,萃取剂中水与丙三醇的体积比为1.0,溶剂比为1.5时,经过三级错流萃取,丙酸甲酯的质量分数达到99.5%以上,收率达98%,且实验值和模拟值之间基本一致。     

采用K2CO3分离丙烯腈-水恒沸体系的研究

测定了丙烯腈-水-碳酸钾体系在25℃时的液-液相平衡数据,相平衡结果表明当水相中K_2CO_3浓度为52．50%时,有机相中丙烯腈的浓度高达98．85%。采用K_2CO_3浓盐水为盐析剂分离丙烯腈-水体系,当60．0%K_2CO_3水溶液与88%丙烯腈/12%水的丙烯腈-水恒沸物的质量比为0．25时,有机相中丙烯腈的浓度高达98．39%,将有机相精馏可得到99．5%丙烯腈产品。     

醋酸正丙酯萃取提纯工艺研究

针对醋酸正丙酯生产过程中分离提纯困难,生产能耗高的现状,研究了由盐类组成复合萃取剂在醋酸正丙酯分离中的应用。该萃取剂在常温下可改变醋酸正丙酯-正丙醇-水体系的互溶度,大幅度提高组分在二相中的分配系数和选择性系数。研究了工艺参数对醋酸正丙酯提纯效果的影响,萃取比为0.8,经三级错流萃取后,有机相中酯的质量分数从93.87%提高到98.44%,比传统工艺可以节能35.2%,萃取剂回收容易,同时能增大原设备的生产能力。     

醋酸甲酯和甲醇热集成变压精馏分离工艺模拟与优化

基于对醋酸甲酯与甲醇二元共沸特性的分析,提出热集成变压精馏分离醋酸甲酯和甲醇的工艺. 利用Aspen Plus软件对该分离过程进行模拟,以NRTL活度系数方程为物性计算方法,其二元相互作用参数由气液相平衡数据回归,分析了加压塔和常压塔的理论板数、进料位置及回流比对分离效果的影响,并进行了能耗比较. 结果表明,该工艺能很好地分离醋酸甲酯和甲醇,较佳的工艺条件为：加压塔操作压力909 kPa,理论板数32,第21块板进料,回流比4.2,塔釜醋酸甲酯纯度99.8%;常压塔操作压力101 kPa,理论板数30,第20块板进料,回流比4.6,塔釜甲醇纯度99.0%. 与常规变压精馏相比,热集成变压精馏可节能达45.8%;与以水为萃取剂的萃取精馏分离工艺相比,热集成变压精馏分离工艺更适合醋酸甲酯与甲醇体系的分离.     

醋酸甲酯-甲醇-水的分离方法比较及展望

综述了醋酸甲酯-甲醇-水的分离方法,对反应精馏、萃取精馏、加盐萃取精馏等方法进行了概括和总结,比较醋酸甲酯提取工艺、条件、纯度及得率等因素,得出采用液液萃取法,具有工艺简单、能耗低等特点,有较好应用前景.     

加盐萃取-精馏耦合分离苯-环己烷共沸物

采用N,N-二甲基甲酰胺(DMF)+硫氰酸钾(KSCN)萃取分离苯-环己烷共沸物,并用常规间歇精馏处理富含苯的萃取液。考察了不同溶剂与原料液的体积比、盐质量分数对该体系分配系数及选择系数的影响,并进行了多级错、逆流萃取实验及精馏实验。实验结果表明:7级错流萃取可得摩尔分数大于97%(脱溶剂摩尔分数)的环己烷;5级逆流可得摩尔分数大于75%(脱溶剂摩尔分数)的环己烷;精馏后的萃取液,苯摩尔分数可达98%以上,DMF+KSCN摩尔分数可达96%以上。加盐萃取-精馏耦合分离苯-环己烷共沸物可得到令人满意的分离效果,是一种绿色节能的新方法。     

加盐萃取精馏分离苯-环己烷

测定不同萃取剂和盐对苯-环己烷共沸物相对挥发度的影响,研究不同质量分数的盐和萃取剂与原料液体积比对苯-环己烷体系相对挥发度的影响以及萃取剂加入速率和回流比对加盐萃取精馏的影响,按实验确定的最佳工艺条件进行重复实验。结果表明:采用N,N-二甲基甲酰胺(DMF)作为萃取剂,加入质量分数为15%的KAc,萃取剂与原料液体积比为0.75,萃取剂加入速率为6 mL/min,回流比为3,可得到纯度大于98%的环己烷。与常规萃取精馏相比,加盐萃取精馏所需萃取剂与原料液体积比小,所得环己烷的纯度较高。塔底釜液经减压精馏,可得质量分数大于99.5%的苯和苯质量分数小于0.15%的加盐萃取剂。     

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.     

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.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。