{001}TiO2纳米片的制备及不同含F量对其光催化活性的影响

以钛酸丁酯为钛源、HF为形貌控制剂,采用简单的水热法合成了具有高催化活性表面的{001｝面纳米TiO2.利用X射线衍射、紫外-可见光漫反射光谱及透射电镜等技术对样品形貌和结构进行表征,并以罗丹明B的光催化降解为模型反应,考察了不同HF量对{001}面TiO2光催化活性的影响.结果表明,{001}面TiO2具有良好的锐钛矿晶型,为纳米片层结构,在紫外光下具有较{ 101｝面TiO2更高的光催化活性,且随着F含量增加,其光催化活性先逐渐增加后减小,F/Ti物质的量比为1.25时其光催化活性最高,紫外光照射20 min后罗丹明B降解率可达80％以上.     

UV/TiO2/Fenton体系催化氧化降解罗丹明B的研究

研究在紫外光照射下,Fenton试剂在纳米级TiO2催化作用下氧化降解罗丹明B的处理效果及机理,分别研究初始反应溶液的pH值、反应时间、FeSO4投加量、H2O2溶液投加量、反应温度、TiO2投加量对处理效果的影响,确定了最优反应条件。对于100 mg/L,500 mL的罗丹明B溶液,当TiO2的投加量为0.03g,18mol/L FeSO4的加入量为5 mL,30%H2O2溶液的加入量为1.7 mL,反应溶液pH值为3时,罗丹明B的去除率随着反应温度的升高而升高,最高去除率达100%。     

Fe_3O_4/TiO_2复合物在光催化降解罗丹明B的应用

以Fe_3O_4/TiO_2为催化材料,分别研究了催化剂在不同催化剂的投加量、不同pH以及不同光照条件下对罗丹明的光催化效果,并用表观速率常数k评价催化剂的光催化活性。研究表明:罗丹明B的光催化反应为一级动力学反应,且在Fe_3O_4/TiO_2复合物投加量在20 g·L~(-1)、pH=6、紫外光照射的条件下降解效率最高。     

基于多因素的光催化降解动力学模型的研究

以纳米TiO2为光催化剂,罗丹明B为降解对象,在KL-1型紫外光实验装置中研究多种因素对光催化降解的影响并建立动力学模型.模型的主要参数有:罗丹明B初始浓度、TiO2投加量、溶液pH以及已知化合物的物理性质(分子的摩尔体积和溶解度).建立的模型表明,反应速率常数与降解物初始浓度呈现线性关系,而与催化剂投加量的关系和单峰...     

含钛炉渣制光催化剂催化降解罗丹明B废水的研究

用含钛炉渣制备了光催化剂GN,通过催化降解罗丹明B废水,分析了催化剂投加量,废水pH值等因素对脱色率的影响.实验结果表明:催化剂GN具有较高的光催化活性,选取适当的催化剂投加量以及合适的废水pH值有助于罗丹明B的降解,GN最佳投加量为0.25g·L-1,适宜的废水pH值为2.当罗丹明B废水浓度为25mg·L-1时,在最佳条件下,光催化反应1h后,罗丹明B废水的降解率达95％以上.     

纳米TiO2/AC光催化降解罗丹明B废水的研究

采用负载型纳米TiO2/AC在流化床反应器中降解罗丹明B染料废水。试验结果表明,罗丹明B的光催化降解率受反应条件的影响较大,其最佳工艺条件：进水罗丹明B质量浓度80mg／L、催化剂为10g／L、pH2．5、H2O2投加量3．5mL／L、反应时间30min,此条件下罗丹明B的光降解率可高达96．1％。     

絮凝法制备TiO2/MCM-41复合光催化剂及其性能的研究

以MCM-41分子筛为介孔材料,采用絮凝法制备复合光催化剂,通过XRD对复合光催化剂的晶型结构和形貌进行了表征,以人工合成染料罗丹明B为降解对象,考察絮凝pH、煅烧时间、煅烧温度、光照时间、催化剂投加量对复合光催化剂活性的影响。实验结果表明：在絮凝pH值为4时所得絮凝污泥,经700℃煅烧2h后的复合光催化剂具有最佳的光催化活性,在紫外光下照射浓度为20mg/L的罗丹明B 40min可获得98%以上的降解效果。     

TiO2/浮石光催化降解活性艳红X-3B的中试研究

采用TiO2/浮石悬浮态光催化剂,对活性艳红X-3B模拟废水进行了光催化降解的中试研究.考察了催化剂投加量、曝气量、溶液pH、投加助剂H2O2、污染物初始浓度对光催化效率的影响.结果表明,TiO2/浮石在中试条件下对活性艳红X-3B有较好的降解效果;催化剂最佳投加质量浓度为45g/L,增大曝气量和pH,适当投加助剂H2O2有利于光催化降解效率的提高;活性艳红X-3B的光催化降解过程符合负一级反应动力学规律,反应速率常数与活性艳红X-3B模拟废水初始浓度之间具有近似负一级的动力学关系.     

超声波降解罗丹明B的研究

报道了用超声波诱导降解模拟水中低浓度罗丹明B染料废水的可行性实验.实验探讨了频率、功率、初始pH、O2、S2O2-8、TiO2光催化对降解速度的影响.实验结果表明:在功率为100%,频率为59 kHz,低pH,充O2饱和条件下,罗丹明B去除效果较好,在紫外光存在下加入S2O28能加快罗丹明B的降解,在TiO2光催化协同作用下,连续反应100 min,2.5 mg/L的罗丹明B 溶液去除率达88.37%.     

化学复合镀法制备多孔光催化材料及其光催化性能

以多孔泡沫镍为载体,采用化学复合镀法制备了性能优良的多孔光催化材料,以产品对水中罗丹明B的降解性能为评价指标,对产品的光催化性能进行评价. 产品对水中罗丹明B的光催化降解反应严格符合零级动力学规律. 化学复合镀制备多孔光催化材料的最佳工艺条件为：镀液中硫酸镍浓度20 g/L,次亚磷酸钠浓度20 g/L,施镀过程中纳米TiO2投加量0.28 g/L,镀液温度90℃,镀液pH值4.6. 各因素影响产品性能的顺序为硫酸镍浓度>次亚磷酸钠浓度>镀液温度>镀液pH值>纳米TiO2投加量. 纳米Bi2O3复合使产品的光催化性能下降,随着纳米Bi2O3复合量增加,产品的光催化性能提高. ZnO复合使产品的光催化性能有明显改善,随着纳米ZnO复合量的增加,产品的光催化性能提高. Ag修饰导致Bi2O3复合光催化材料的光催化性能下降、ZnO复合光催化材料的光催化性能提高.     

悬浮式光催化反应器中催化剂的分离

光催化高级氧化技术在深度水处理方面具有降解无选择性、高效、无二次污染的独特优势,光催化反应器是光催化反应高效进行的关键。在众多反应器中悬浮式反应器体现出传质优良、光源利用率高的特点,但催化剂细微颗粒的分离回收难以实现。本文利用自行设计的无机陶瓷膜分离组件对催化剂进行分离回收,对原生粒径21 nm的二氧化钛催化剂颗粒的分离效率达到99%,在操作压力为0.4 MPa时的膜渗透通量约为200 L.m-2.h-1。     

p-n复合半导体光催化剂研究进展

综述了p-n复合半导体光催化剂的光催化原理及研究现状。根据p-型材料种类,将p-n复合半导体光催化剂分为4类:p-型半导体材料为镍氧化物、p-型半导体材料为钴氧化物、p-型半导体材料铜氧化物及由其它p-型半导体材料组成的"p-n结型"、"二极管"式p-n复合半导体光催化剂,分别对其研究状况进行了介绍。提出了当前p-n复合半导体光催化剂研究中存在的一些问题,并对未来的研究方向进行了探讨。     

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.