用水量对溶胶-凝胶法制备氮掺杂纳米二氧化钛的影响

采用两种用水量的溶胶-凝胶工艺制备了氮掺杂二氧化钛(N-TiO2)纳米颗粒粉末,对样品进行了X射线衍射、透射电子显微镜、X射线光电子能谱及紫外-可见漫反射谱分析,并以甲基橙的光催化降解实验研究了样品的可见光催化性能。结果表明:采用用水多的溶胶-凝胶工艺可获得可见光催化活性高的N-TiO2,且N-TiO2的颗粒粒径较小;由于溶胶中过量的N掺杂剂可在N-TiO2前驱体凝胶离心分离时被去除,可进行较低温度的煅烧,易于获得N掺杂浓度较高的N-TiO2。另外,采用用水多的工艺时,氮掺杂剂对TiO2颗粒的氮化及凝胶化过程也有很大的影响,有些含氮化合物作为掺杂剂可能会明显降低N-TiO2的可见光催化活性。     

掺Ag,Ni对TiO2气相光催化活性的影响

采用溶胶-凝胶法制备了以活性炭为载体的负载型Ag/TiO2及Ni/TiO2光催化剂,以气相中甲苯降解反应考察了两种催化剂的活性随金属离子掺杂量的变化. 用透射电镜、X射线衍射及荧光光谱对掺杂催化剂进行了表征. 结果表明,经Ag, Ni掺杂后,Ag/TiO2和Ni/TiO2两种催化剂的催化活性均有不同程度的提高,且Ni/TiO2优于Ag/TiO2. 两种催化剂的最佳掺杂量均为0.4%. 根据表征及实验结果分析了金属离子不同掺杂量影响TiO2光催化活性的机理.     

纳米Ag-TiO2/ITO光催化膜的制备、表征及光催化活性的研究

用直接光还原法将Ag+沉积到TiO2膜表面制备了纳米Ag TiO2/ITO光催化膜,该光催化膜分别用紫外可见光漫反射、X射线衍射、扫描电镜进行了表征;并以甲酸为模型化合物,研究了Ag TiO2/ITO光催化膜对有机污染物的光催化氧化降解。实验结果表明:沉积于TiO2膜表面的银是以Ag(0)形式存在,且Ag可以作为光生电子载体,对抑制光生电子-空穴的复合有明显的促进作用,但Ag TiO2/ITO膜的光催化活性与Ag的沉积量密切相关,其中以Ag沉积质量分数为1 1%的Ag TiO2/ITO膜的光催化活性最佳,其光催化氧化甲酸的速率常数约为TiO2/ITO膜光催化速率常数的2 2倍。     

Fe3+/Zn2+复合掺杂纳米TiO2的结构及光催化性能

采用溶胶-凝胶工艺,以钛酸丁酯(Ti(C4H9O)4)为前驱体,冰醋酸为螯合剂,制备了Fe3 /Zn2 复合掺杂的改性纳米TiO2粉体材料.运用X射线衍射、透射电镜、X射线光电子能谱、Fourier变换红外光谱和光吸收研究了铁锌元素掺杂对纳米TiO2相变和光催化活性的影响.结果表明:铁及锌的掺杂会降低TiO2由锐铁矿相向金红石相的转变温度;掺铁和锌能提高纳米TiO2的光催化活性;当Fe3 /Ti4 摩尔比为0.2,Fe3 /Zn2 摩尔比为0.5时,经300℃焙烧1 h制备的Fe3 /Zn2 复合掺杂纳米TiO2样品的光催化活性最好;在太阳光照4h时,Fe3 /Zn2 摩尔比为0.5复合掺杂纳米TiO2样品对甲基橙的降解率可达71.43%.     

Ag/TiO_2纳米纤维薄膜与光催化性能研究

采用新型种子诱导方法合成Ag/TiO2纳米纤维异质结构,通过在TiO2纳米纤维,水,乙醇溶液中加入银氨溶液实验方法制备了Ag/TiO2纳米纤维薄膜。用场发射电子显微镜(FESEM),能量色散X射线光谱(EDX),透射电子显微镜(TEM),X射线粉晶衍射(XRD),X射线光电子能谱(XPS)来表征最终产物。结果表明这些TiO2纳米纤维的直径大约80 nm,长度在几百微米之间,而负载在其上面的Ag粒子大小可达300~700 nm。将上述制取的光催化薄膜进行过滤甲胺磷水溶液实验,甲胺磷溶液降解可达87.0%,表明了TiO2纳米薄膜的光催化活性得到了很大提高。该材料将有可能应用于光催化、消毒、杀菌、环境(水、空气)污染处理等方面。     

N-TiO2/Ti3C2复合材料的原位合成及其光催化性能

以钛碳化铝、氢氟酸、氟硼酸钠为原料，以尿素为氮源，通过简单的溶剂热反应，在高导电性的Ti3C2 MXenes（二维过渡金属碳化物）纳米片上原位生长氮元素掺杂的TiO2纳米片，合成了二维N-TiO2/Ti3C2光催化复合材料。采用X射线衍射仪、扫描电子显微镜、透射电子显微镜、X射线光电子能谱仪、紫外-可见漫反射光谱仪、光致发光光谱仪等对催化剂样品进行了结构表征。结果表明，在可见光照射下，N-TiO2/Ti3C2复合材料对罗丹明B（RhB）表现出较好的光催化降解性能，其降解速率是纯TiO2的8.41倍，在150min内，罗丹明B降解率达到96.3%。这主要是由于氮元素的掺杂缩小了TiO2的带隙，将光响应范围扩展到可见光区域。同时，TiO2纳米片的原位生长使其与具有优异电导率的Ti3C2 MXenes纳米片形成了紧密的接触界面，促进了光生载流子的分离和迁移。自由基捕获实验和电子自旋共振测试结果显示，•O2-和•OH是N-TiO2/Ti3C2光催化体系降解罗丹明B的主要活性物种。此外，N-TiO2/Ti3C2复合材料具有良好的稳定性和可重复利用性。     

Fe,N共掺杂TiO_2/SiO_2复合材料的制备及光催化性能

采用溶胶—凝胶法制备了掺杂不同量Fe,N的TiO2/SiO2复合纳米粒子。通过红外光谱、X射线衍射、透射电子显微镜等对制备的样品的结构和形貌进行表征。以甲基橙水溶液的光催化降解为模拟反应,在紫外光照射下评价了样品的光催化活性。结果表明:Fe,N共掺杂TiO2/SiO2为核壳结构,SiO2核与TiO2壳间形成了Ti—O—Si键。由于金属Fe3+离子抑制光生载流子的复合,非金属N降低了TiO2/SiO2的带隙能,Fe,N共掺杂的协同作用使复合TiO2/SiO2具有更好的光催化性能。共掺杂0.05%Fe及0.05%N的TiO2/SiO2复合光催化粒子的催化活性最高,光照1h后对甲基橙的降解率提高到52%。     

基于DEA络合剂的Ag负载纳米TiO2制备及性能研究

以二乙醇胺(DEA)作为络合剂,采用溶胶-凝胶法在低温条件下合成了Ag负载纳米TiO2,用XRD、TEM、XPS等测试手段进行表征,分析了DEA对Ag负载的作用机理,并测试了Ag/TiO2的光催化活性和抗菌性能.结果表明:采用DEA作为络合剂和还原剂,可在低温条件下将银单质均匀负载于纳米TiO2表面,银以多晶团簇形式存在.降解亚甲基蓝的光催化活性测试显示,适量的银负载可显著提高纳米TiO2的光催化活性.同时,光触媒和银的协同作用赋予Ag/TiO2更加优异的抗菌性能.     

N-TiO2/g-C3N4复合光催化剂的制备及其光催化性能

采用水热法制备N掺杂TiO2,将其与二氰二胺混合进行高温焙烧合成N-TiO2/g-C3N4复合光催化剂。采用XRD、UV-Vis、N2吸附-脱附和SEM等对催化剂进行微观结构表征,以200W氙灯模拟光源并过滤掉420nm以下的紫外光,对比研究TiO2、g-C3N4、N-TiO2和复合光催化剂对罗丹明B的可见光降解性能。结果表明,N掺杂后TiO2的禁带宽度降低,催化活性提高;而复合光催化剂可见光吸收边距相对N-TiO2进一步红移,禁带宽度为2.75eV,降解罗丹明B的一级动力学常数k可达0.12158min-1,是g-C3N4、N-TiO2的2倍;复合催化剂重复使用4次后,对罗丹明B的降解率仍达92%以上,表明催化剂具有较好的光催化活性和稳定性。     

钌掺杂二氧化钛纳米粉体的制备及光催化性能

以钛酸四丁酯为原料,利用溶胶-凝胶法制各了纯TiO2和Ru掺杂的TiO2纳米粉体.利用热重-差热分析、X射线衍射、X射线光电子能谱和紫外-可见分光光度计对粉体进行了表征.在模拟太阳光下,利用含酚水溶液中苯酚的光催化降解反应,考察了TiO2纳米粉体的光催化活性和Ru的掺杂量对光催化活性的影响.结果表明:Ru的掺杂延缓了T...     

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。