疏水改性MCM-41材料对邻苯二甲酸二丁酯的吸附

基于介孔分子筛亲水性强、对疏水性有机污染物吸附效果不佳的问题,采用3,3,3-三氟丙基三甲氧基硅烷作为改性剂对MCM-41分子筛进行表面修饰,制得疏水性的MCM-41。利用XRD、FT-IR等表征方法对材料进行表征,以邻苯二甲酸二丁酯为目标污染物,考察材料的吸附性能。结果表明,所制备的改性MCM-41材料结构性能良好,改性基团成功接枝到分子筛表面;3,3,3-三氟丙基接枝的TFP-MCM-41材料疏水性强于丙基接枝的P-MCM-41和未改性的MCM-41,相应地,其对邻苯二甲酸二丁酯的吸附效果也高于后两者。中性及酸性条件下p H的变化对DBP吸附影响很小,碱性条件不利于DBP吸附。     

MCM-41表面基团对α-生育酚/MCM-41/LDPE薄膜性能的影响

先采用3-氨丙基三乙氧基硅烷、三甲基氯硅烷、N-辛基三甲氧基硅烷等硅烷偶联剂对MCM-41介孔材料进行氨基和不同长度的烷基链后嫁接处理,然后将天然抗氧化剂α-生育酚负载于表面修饰前后的MCM-41,再与低密度聚乙烯(LDPE)熔融共混制备抗氧化活性食品包装膜。对α-生育酚/MCM-41组装体及活性膜的性能进行表征分析,研究表面修饰前后不同表面基团对活性膜微观形貌、结晶性的影响;此外,通过迁移试验研究MCM-41表面修饰对薄膜控释性能的影响,开发具有不同控释行为的抗氧化活性薄膜。结果表明,疏水性基团的嫁接提高了组装体在非极性聚合物基质中分布的均一性;由于MCM-41表面嫁接了有机官能团,聚合物的结晶度得到提高;烷基链长度增加,α-生育酚在活性膜中的释放速率减缓,嫁接氨丙基的MCM-41对α-生育酚的缓释效果最明显,释放速率相较于未嫁接以前降低了约71%。     

介孔分子筛MCM-41在废水处理中的应用

介孔分子筛MCM-41具有高度有序排列的孔道结构、孔径均匀且尺寸可调、高比表面积、较大的孔体积及吸附容量,孔道表面具有易于修饰的硅羟基,在废水处理中吸附重金属离子、有机污染物等方面具有很大的应用价值。对近几年介孔分子筛MCM-41用于处理废水中污染物的应用情况进行了综述。     

有机氯硅烷修饰的介孔SBA-15及其疏水性

在非极性溶剂(甲苯)中,用三甲基氯硅烷和苯基二甲基氯硅烷对全硅介孔分子筛SBA-15进行了表面修饰.利用傅里叶变换红外光谱(FT IR)、X射线粉末衍射(XRD)和低温N2吸附-脱附等手段对样品进行了结构分析;并通过测定样品在水或正己烷饱和蒸汽中的吸附量,研究了它们的疏水性.结果表明,表面改性后的SBA-15仍保持完好...     

疏水性MCM-41分子模板剂对水中U(VI)的吸附性能试验研究

采用水热合成法制备了疏水性介孔二氧化硅材料(MCM-41-dry)并经煅烧制得亲水性介孔二氧化硅材料(MCM-41-cal).试验探讨了pH值、吸附时间、投加量以及U(VI)初始浓度等因素对MCM-41材料煅烧前后吸附U(VI)效果的影响,利用SEM、EDS、BET和FTIR分析其吸附机理.试验结果表明, MCM-41-dry材料因具有有机模板剂,其吸附效果远高于MCM-41-cal的吸附效果;当pH值为5,吸附时间为180 min,温度为30 ℃,MCM-41-dry投加量为0.2 g/L,U(VI)初始浓度为10 mg/L时,其对U(VI)的吸附率可达99.2%;Langmuir吸附等温模型和准二级动力学方程能较好的拟合其吸附过程,当T=303 K时,理论饱和吸附量为241.935 mg/g,吸附为单分子层吸附,以化学吸附为主.通过BET、FTIR表征则说明MCM-41-dry具有六方形介孔结构能吸附U(VI),官能团羟基和氨基发挥了很大的作用.     

疏水性MCM-41分子模板剂对水中U(Ⅵ)的吸附性能试验研究

采用水热合成法制备了疏水性介孔二氧化硅材料(MCM-41-dry)并经煅烧制得亲水性介孔二氧化硅材料(MCM-41-cal)。试验探讨了pH值、吸附时间、投加量以及U(Ⅵ)初始浓度等因素对MCM-41材料煅烧前后吸附U(Ⅵ)效果的影响,利用SEM、EDS、BET和FTIR分析其吸附机理。试验结果表明,MCM-41-dry材料因具有有机模板剂,其吸附效果远高于MCM-41-cal的吸附效果;当pH值为5,吸附时间为180 min,温度为30℃,MCM-41-dry投加量为0.2 g/L,U(Ⅵ)初始浓度为10 mg/L时,其对U(Ⅵ)的吸附率可达99.2%;Langmuir吸附等温模型和准二级动力学方程能较好的拟合其吸附过程,当T=303 K时,理论饱和吸附量为241.935 mg/g,吸附为单分子层吸附,以化学吸附为主。通过BET、FTIR表征则说明MCM-41-dry具有六方形介孔结构能吸附U(Ⅵ),官能团羟基和氨基发挥了很大的作用。     

双功能硅烷化修饰MCM-41固载Cosalen催化环己烷氧化

采用双功能硅烷化试剂γ-氨丙基甲基二乙氧基硅烷(AMS),对(MCM-41)全硅介孔分子筛一步进行氨基官能团化和甲基疏水性修饰,然后将双水杨醛缩乙二胺合钴(Cosalen)通过氨基的轴向配位固载在修饰后的载体MCM-41上。X射线衍射和N2物理吸附/脱附的结果表明:经过AMS双功能硅烷化修饰以及固载Cosalen后载体的孔道结构保持良好。考察了硅烷试剂用量对硅烷化效率的影响,结果表明:当AMS的加入量为4.00mmol/g时,甲基修饰量达到1.95mmol/g;水和环己烷的静态吸附结果表明硅烷化修饰后,催化剂载体的疏水性明显增强。制得的催化剂应用于环己烷的分子氧氧化反应,130℃反应2h,环己烷转化率达到7.2%,环己醇和环己酮总选择性达到70.5%,较未经AMS修饰的催化剂Cosalen/MCM-41获得的醇酮总选择性提高了13%。     

MCM-41介孔材料的合成条件和特性对吸附镉离子的影响

以气相氧化硅为硅源,十六烷基三甲基溴化铵(cetyl trimethyl ammonium bromide,CTAB)为模板剂,分别在碱性[氢氧化钠(NaOH),四乙基氢氧化铵,tetraethyl ammonium hydroxide,(C2Hs)4NOH(TEAOH)]和酸性介质条件[盐酸(HCl)]T水热合成了MCM-41有序介孔材料MCM-41-N,MCM-41-T和MCM-41-H.用X射线衍射、氮气吸附-脱附等手段对比分析了合成的3种MCM-41介孔材料的物相、比表面积、孔径、孔体积等,发现酸性介质中合成的介孔材料的孔径最大.在此基础上,利用MCM-41介孔材料对比研究了处理含镉离子(Cd2 )废水的效果和机理,确定了不同介孔材料用量、不同初始pH值条件下MCM-41介孔材料对水中Cd2 的吸附率和吸附量.结果表明:介孔材料用量相同时,溶液pH值的增大有利于提高3种MCM-41介孔材料对水中Cd2 的处理效果.在pH值从7.0到8.0的过程中,其吸附率有1个突变,MCM-41-T的Cd2 吸附率从35.65%提高到62.15%;MCM-41-N的从38.80%提高到69.40%;MCM-41-H的从50.22%提高到73.47%.孔径最大的MCM-41-H对Cd2 的吸附效果最佳,最大吸附率为89.56%,最大吸附容量为8.57 mg/g.吸附溶液pH值的大小和介孔材料的孔径尺寸是决定吸附量大小的关键因素,因此,重点应通过优化合成工艺提高介孔材料的孔径.     

硅基纳米材料用于阿司匹林长效缓释的研究

表面活性剂采用十六烷基三甲基溴化铵为活性成分,硅源采用正硅酸乙酯,利用低温水热法合成了MCM-4l介孔分子筛,采用动态吸附法将阿司匹林药物吸附到分子筛MCM-41的孔道中,吸附前后的介孔分子筛分别利用傅里叶红外光谱(IR)、紫外光谱(UV)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)等对吸附前后的分子筛进行了表征;借助紫外-可见吸收光谱(UV)研究了分子筛的最大吸附量、吸附时间、体外释放等。结果显示,所合成的分子筛MCM-41有序的介孔材料;MCM-4l用于药物阿司匹林的载体最大载药量为:45mg·g-1(m(药物)/m(载体))和良好的缓释效果。     

金属掺杂介孔分子筛MCM-41的合成及结构表征

采用水热法合成了不同金属原子(M=Ce,Y,Nd)掺杂的MCM-41介孔分子筛M-MCM-41,采用X射线衍射(XRD)、N2吸附-脱附、透射电镜(TEM)、X射线光电子能谱(XPS)和NH3程序升温脱附(NH3-TPD)对M-MCM-41介孔分子筛的介孔结构,金属化合价态及表面酸性进行表征。结果表明,M-MCM-41介孔分子筛仍具有典型的六方介孔结构特征,样品比表面积、孔容积降低,孔径增大,引入分子筛中金属元素以M3+形态存在,金属离子的掺杂使M-MCM-41产生酸性位,对应中强酸。     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

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.     

ICP-MS法测定地球化学样品中As、Cr、Ge、V等18种微量痕量元素的研究

建立了测定地球化学样品中包括As、Cr、Ge、V等18种微量、痕量元素的ICP-MS方法。地化试样用HF-HNO3混酸分解后,以1 1 HNO3溶解干渣。由于制样不使用盐酸,避免了Cl对As、Cr、Ge、V的质谱干扰。用国家一级地球化学标准物质GBW 07309制备溶液优化仪器工作参数,并用于校准。方法测定限(6s)为:0.007~6.4μg/g,精密度(RSD%,n=12)为:29%~9.4%,经过国家一级地球化学标准物质的分析验证,结果与标准值吻合。方法已应用于国土资源调查的试样分析。