粉煤灰制备沸石分子筛的研究进展

本文综述了利用工业废弃物-粉煤灰合成沸石分子筛的最新进展,包括水热法、两步法、碱熔融法等合成工艺,评价了各种合成方法的特点及存在的问题,并对粉煤灰合成沸石分子筛在化工行业、水处理、废气治理以及放射性废物处理等领域的最新应用进展进行了介绍,展望了粉煤灰合成沸石分子筛的研究及应用前景.     

粉煤灰基X型沸石分子筛的合成制备及其去除氨性能研究

粉煤灰是燃煤电站的主要副产物,是全球性的重大环境问题,对公众健康和环境污染构成威胁.本研究提出了一种利用工业废弃物粉煤灰合成制备X型沸石分子筛的有效工艺,系统分析了不同条件下,固体碱预处理和引入晶种对合成X型沸石分子筛性能的影响,探讨了X型沸石分子筛对铵离子去除率的影响.结果表明:OH-浓度、Si/Al比、固液比、陈化时间和晶化时间对合成X型沸石分子筛的最化条件分别为0.75 mol/L、2.8、9 mL/g、0.5 h和10 h,实现了对NH+4的高效去除.有效降低了分子筛制备成本,实现了粉煤灰的资源化、高值化利用,实现"以废治废"双赢目标.     

粉煤灰基沸石分子筛的合成及应用进展

煤炭在燃烧利用过程中产生大量的粉煤灰。我国粉煤灰产量高居世界第1位,由于综合利用率只有70%,仍有大量粉煤灰露天堆存,造成严重的环境污染和资源浪费。消除粉煤灰的环境污染、提高其资源化利用率对我国循环经济的发展具有重要的现实意义。我国粉煤灰的利用由早期的粗放型规模化利用逐渐向精细型高值化利用转变。由于粉煤灰中富含硅铝元素,以粉煤灰为原料合成沸石分子筛是近年来粉煤灰高值化利用的研究热点。从4个方面对粉煤灰基沸石分子筛的合成及应用展开论述。首先,介绍了粉煤灰的形成、物化性质及其危害和治理利用现状。粉煤灰是一些矿物组成不同、形态不同的颗粒的机械混合物,其性质与原煤的成分、产地和燃烧方式有关。而粉煤灰的特性是决定其综合利用方式的关键。其次,论述了粉煤灰的3种主要活化方式,包括机械活化、水热活化和碱(盐)融活化。粉煤灰中的硅铝元素主要以非晶矿物玻璃体形式存在,其表面是致密的玻璃质外壳,粉煤灰合成沸石分子筛的关键问题是如何使硅和铝被充分活化,并得到有效利用。相比于机械研磨活化和碱(盐)熔融活化,水热活化有更高的活化效率和较低的能耗。第3部分论述了粉煤灰基沸石分子筛放入水热合成方法,重点介绍了直接水热合成法、碱融-水热合成法、微波/超声波-水热合成法、晶种法和转晶法。粉煤灰合成沸石分子筛一般均基于水热合成过程,多步水热处理可提高产物纯度,辅以超声、微波、碱熔融和添加晶种等方法可提高产率、晶化速率和结晶度。转晶法可极大拓展粉煤灰基沸石的骨架类型和酸性位,是更有利的粉煤灰基沸石分子筛的制备技术。最后,概述了粉煤灰基沸石分子筛的应用。粉煤灰基沸石分子筛的应用尚处于探索阶段,主要用于环境治理领域,包括工业废水中重金属离子的吸附脱除、大气污染物的吸附脱除以及温室气体CO2吸附。     

粉煤灰分步溶出硅铝制备纯沸石分子筛的研究

研究了一种由粉煤灰合成纯沸石分子筛的新工艺,粉煤灰与碳酸钠混合焙烧生成硅酸钠和硅铝酸钠,用少量水浸取其中的硅酸钠,含硅铝酸钠的残余物用碱液浸取.实验发现,在碱溶过程中溶液中的硅铝存在过饱和现象,在过饱和期内实现固液分离,可提取粉煤灰中的硅铝用于合成X型、A型、P型纯沸石产品.1 kg粉煤灰合成310～560 g纯沸石.晶化导向剂和晶种对沸石晶型和晶化时间有很大影响.经仪器和化学分析方法对沸石产品从矿物组成和阳离子交换容量进行表征,制得产品的阳离子交换容量可达3.2～ 4.7meq/g,纯度较高.     

碱熔融粉煤灰合成沸石分子筛的影响因素分析

评述了碱熔融粉煤灰合成沸石的方法;分析了该法合成沸石过程中的影响因素,这些因素主要包括粉煤灰的组成、碱灰比、焙烧温度及时间、晶化温度及时间;探讨了目前研究的情况及未来研究的方向,这些分析为碱熔融法今后的应用提供理论依据.     

粉煤灰沸石合成研究新进展

粉煤灰是一种化学组分和沸石相似的工业固体废弃物,利用粉煤灰合成具有高附加值沸石产品是粉煤灰综合利用的一个发展方向.本文综述了粉煤灰合成沸石的研究进展,包括传统水热法、碱熔融法、盐热法、逐步升温法、渗析-水热法等合成工艺,并且评价了各种合成方法的优缺点,展望了粉煤灰合成沸石的发展研究方向及粉煤灰沸石的应用前景.     

粉煤灰沸石合成机理、方法及改性技术的研究

首先根据人工合成沸石的空间结构,分析了粉煤灰沸石离子交换性和吸附分离性特性;对粉煤灰合成沸石的合成机理--液相转变机理进行了分析;对水热合成法、碱处理法、盐热法、混碱气相合成法等粉煤灰合成沸石工艺进行了综述,并归纳总结了粉煤灰组成、液固比、碱的种类和浓度、反应温度与反应时间等因素对沸石合成的影响;最后,对粉煤灰合成沸石...     

利用粉煤灰制备沸石分子筛及对含铜废水的处理

以粉煤灰为原料,在温和条件下水热合成粉煤灰基沸石分子筛,并通过正交试验研究了碱浓度、晶化时间、晶化温度对粉煤灰吸附重金属Cu2+性能的影响,确定在晶化时间10 h、晶化温度80℃、NaOH的质量浓度为8％的工艺条件下合成的分子筛对Cu2+吸附效果最好.经X射线衍射仪分析表明,合成的产物含有NaP1型微孔沸石分子筛.通过比表面积分析仪分析测定样品的比表面积为45.98 m2/g.用优化工艺合成的分子筛去除含铜废水,1500 mg/L的沸石处理该废水30 min,去除率达到93.9％,结果表明,合成的分子筛具有良好的吸附性能.因此,本实验合成工艺简单,条件温和,降低了能源成本和最小化环境影响,有利于工业大规模生产.     

制备因素对粉煤灰-锰渣制备沸石分子筛钙离子交换能力的影响

以粉煤灰和锰渣为原料,采用碱熔融-水热合成法制备沸石分子筛.研究了煅烧温度、原料组成、硅铝比、碱浓度、水热时间和温度对钙离子吸附能力的影响,并利用XRD、SEM-EDS、FT-IR和TG-DSC等手段表征了产物的晶体形貌、骨架结构和热稳定性.结果表明,制备沸石分子筛的最佳工艺条件为:煅烧温度800 ℃,锰渣掺量40%,硅铝比3.5,碱浓度3 mol· L-1,水热温度90 ℃,水热时间16 h,在此条件下制备的NaX型沸石分子筛结晶度较高,700℃下骨架结构未发生坍塌,具有较好的热稳定性,钙离子交换量高达392.58 mgCaCO3/g.     

粉煤灰碱熔融-水热法合成A型沸石及吸附性能研究

为利用粉煤灰中的铝、硅资源制备高性能吸附材料,本研究以贵州某地粉煤灰为原料,采用“碱熔融-水热合成法”合成A型沸石,并考察了合成沸石对溶液中Cu2的吸附性能.研究运用单因素法考察不同碱灰比、焙烧时间、晶化温度及晶化时间对沸石合成效果的影响,采用扫描电镜(SEM)、X射线衍射仪(XRD)对合成沸石表面形貌和晶体特征进行表征.在此基础上,考察了粉煤灰合成沸石对模拟料液中Cu2的吸附效果.结果 表明:当粉煤灰原灰中铝硅比约为1∶1,在碱灰比为1.3∶1、焙烧温度650℃、焙烧时间60 min、晶化温度100℃、晶化时间8h条件下,合成了晶型较为理想的A型沸石产品,合成沸石对Cu2吸附效果较好,对溶液中Cu2+的去除率大于95％.     

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.     

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。     

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.