Heterogeneous Photocatalytic Mineralization of Chlorobenzene by Paratungstate-loaded Titania Catalysts in an Aqueous Medium

Paratungstate-loaded titania catalysts were prepared via the addition of a series of aqueous solutions of paratungstate( denoted as W7 ) into an isopropanol solution of Ti[ OCH( CH3 )2 ]4 by means of the sol-gel method. The catalysts were characterized by EDX, BET, FTIR, UV-Vis DRS, XRD and the results indicate that such paratungstateloaded catalysts maintained their heptatungstate structure in the anatase titania matrix up to 400℃. The catalysts were tested for the heterogeneous photodegradation of chlorobenzene in aqueous media and showed a better catalytic activity than P-25 TiO2 because paratungstate can prevent the recombination of the holes and electrons produced during irradiation. Moreover, the paratungstate-loaded titania catalysts can resist the disaggregation during the photoirradiation and can be easily recycled from the aqueous suspensions after reactions.     

双孔块状SiO2载体材料的孔结构及其酶活性的研究

SiO₂ monoliths with double-pore structure were synthesized with tetraethyl orthosilicate, polyethylene glycol, starch, ethanol and ammonia as the main raw materials via a sol-gel route. The effect of different content of starch of the samples was studied on the mesopore structure, macropore appearance, hydrothermal stability and enzyme activity to immobilize gluczyme. The results indicate that porous blocks with mesopores of 10～12 nm and macropores of 10～30 μm can be formed by the removal of polyethylene glycol and starch after heating at 600 ℃. The minimal density of the obtained samples was 0.34 g·cm^-3 and the maximal porosity was 76%. After being immersed in water at 80 ℃ for 7 d, the density, porosity and shape of N₂ adsorption-desorption curves of the samples were almost unchanged, showing that the sample has a good hydrothermal stability. The initial enzyme activity of sample P2KD30 was 11 190 U, and definite enzyme activity could be maintained after five cycles.     

A facile one-step route to synthesize titania hollow microspheres with incontinuous multicavities

The titania hollow microspheres with incontinuous multicavities were successfully fabricated via an oil/ water(O/W) emulsion process accompanied by sol–gel reaction in the presence of polyvinylpyrrolidone(PVP). In the one-step route, the addition of PVP to the tetrabutyl titanate(TBT) 1-octanol solution as the oil phase of the O/W emulsion clearly expands the size of the cavities inside the microspheres. The and atoleine alters the polarity of the oil phase to affect the interior structure significantly. The Span 80 is used as a stabilizer to preserve spherical shape. A preliminary mechanism based on phaseseparation for the structural evolution of titania hollow microspheres with multicavities is suggested. Zirconia and alumina hollow microspheres with incontinuous multicavities can also be prepared by this one-step route successfully.     

Preparation and characterization of perfluorosulfonic resin/titania hybrid transparent films

Preparation and characterization of perfluorosulfonic resin/titania organic-inorganic hybrid films were presented. The transparent hybrid films were prepared by hydrothermal treatment at low temperature of a mixed solution of tetrabutyl titanate and perfluorosulfonic resin with the help of acetylacetone. The characterization was carried out by SEM,XRD,FT-IR,UV-Vis and TGA. The results showed that the perfluorosulfonic resin/titania hybrid transparent films were composed of titania particles dispersed in the perfluorosulfonic resin matrix very well and the titania was of anatase phase. Its diameter de-creased with increasing weight ratio of titania to perfluorosulfonic resin.     

用于太阳光光催化降解溴化乙锭的高活性锆掺杂锐钛矿型二氧化钛催化剂的制备和表征

Ethidium bromide is a fluorescent tag and is used in biomedical applications.It is a potent mutagen because of its DNA intercalating nature.A catalyst composition for the feasible elimination of ethidium bromide using a broad spectrum of solar radiation was investigated.Nanostructured anatase TiO2 was synthesized by gel to crystalline conversion and its bandgap was engineered by doping with zirconium to effectively harness sunlight.The doped nanocrystals were characterized by X-ray diffraction,scanning electron microscopy,transmission electron microscopy,energy dispersive X-ray analysis,and UV-Vis spectroscopy.The formed crystals retained the anatase phase with a marginal increase in size.The pulverization process used to dope Zr into titania resulted in a nano and doped lattice with an increased and extended light absorption range,which gave a nearly five-fold increase in photoactivity over pure titania.The catalytic effect of the modified titania,the dopant concentration,and the dynamics of the dopant concentration on the charge carriers(trapping-recombination)for the degradation of the mutagen was investigated.The modified titania is capable of total ethidium bromide elimination in sunlight.The loss of its mutagenic property was confirmed by an Ames test.The induced revertant colonies observed were nil in the treated sample indicating a complete loss of the intercalating property of the mutagen.     

Preparation,Characterization,and in vitro Release of Biodegradable Erythromycin-gelatin Microspheres

Blank and erythromycin-loaded gelatin microspheres were successfully fabricated via emulsion chemical- crosslinking technique. The surface morphology of the microspheres was characterized by scanning electron microscope（SEM） and optical microscope. The results show that the microspheres were spherical and smooth. The particle average size of erythromycin-loaded microspheres was found to be 20.6 μm, with a high purity of more than 90% and with a good dispersibility. The microspheres could be obtained in a high yield. Erythromycin released from the microspheres was monitored in buffer and artificial body fluid at 37 ℃. Average drug content was 27.2%, and erythromycin-loaded gelatin microspheres showed good release profiles with a nearly constant release during 4-8 h in artificial body fluid in vitro degradation studies. These gelatin microspheres are useful for studying and developing various drug-delivery systems.     

Facile Synthesis of Al-pillared Mesoporous Montmorillonite Assisted with Concentrated Al13 Solution

Al-pillared mesoporous montmorillonite was facilely synthesized from concentrated Al13 solution obtained by vacuum concentrating-ultrasonic pillaring strategy.Concentrated Al13 solution could reduce the process of pillare and increase pillaring efficiency.The absolute value of layer distance could be increased by 0.96 nm via concentrated Al13 solution pillare.27Al NMR indicates that Al Keggin ions of concentrated Al13 are arranged in a more regular way by vacuum concentrating method.The Al-pillared mesoporous montmorillonite from concentrated Al13 solution has bigger specific surface area and even pore size distribution which were characterized by X-ray diffraction（XRD） and nitrogen adsorption measurement.Furthermore the catalytic activity of Ai-pillared montmorillonite loaded Ni and Mo catalysts was tested by the hydrodesulfurization of thiophene.The thiophene conversion reached 77.5％,which was higher than the corresponding value reported in the literature.     

Molybdosphoric Acid Mixed with Titania Used as a Catalyst to Synthesize Diphenyl Carbonate via Transesterification of Dimethyl Carbonate and Phenol

The 12-molybdosphoric acid mixed with titania (MPA-TiO2) was found to be a novel and efficient catalyst for the synthesis of diphenyl carbonate (DPC) via transesterification of dimethyl carbonate (DMC) and phenol. The X-ray diffraction (XRD) and infrared (IR) techniques were employed to characterize the prepared catalysts. The effect of the weight ratio of the 12-molybdosphoric acid to titania on the transesterification was investigated. A 13.1% yield of DPC and an 11.6% yield of methyl phenyl carbonate (MPC) were obtained over MPA-TiO2 with the weight ratio of MPA to TiO2 as 5:1.     

Stability of Concentrated Olive Oil‐in‐water Emulsion

The stability of olive oil-in-water (o/w) emulsion stabilized with sucrose fatty acid ester (SFAE) was evaluated through an accelerated ageing test. The stability of the emulsion in this study was examined by the appearance of any phase separation in the emulsion, mean droplet size and rheological properties over one month. The effect of accelerated ageing at 45 ℃ on the emulsion rheological properties was investigated using an amplitude sweep test, a frequency sweep test and a viscometry test. The rheological properties of the emulsion were examined at the one day, one week and one month of storage time. Among the series of emulsions prepared, the emulsion with 2∶8 of water to oil ratio (by weight) is the most stable one, which did not show any of phase separation. The amplitude sweep result shows that there was no significant change of the critical strain of the emulsion throughout one month of storage time. The dynamic properties as well as the steady flow behavior of the emulsion also show no significant changes for over one month of storage time. The mean droplet size of the emulsion remained stable around 2.5 μm within the period of investigation.     

Enhanced hydrogen production activity over BiO_X–TiO_2 under solar irradiation:Improved charge transfer through bismuth oxide clusters

A series of titania nanoparticles and nanotubes deposited with various quantities of bismuth(Bi) were prepared via sol-gel and hydrothermal methods, respectively. They were then characterized using X-ray diffraction spectroscopy(XRD), X-ray photo electron spectroscopy(XPS), UV–Vis diffused reflectance spectra(DRS), photoluminescence spectra(PLS), transmission electron microscopy(TEM), energy dispersive analysis of X-rays(EDAX), and BET surface analysis. These catalysts were employed for the photocatalytic production of hydrogen from a mixture of pure water and glycerol under solar light irradiation. The presence of the Bi~((3+x)+) species was found to play a vital role in enhancing activity while minimizing electron hole recombination(relative to bare TiO_2). The nanotubes exhibited better activity than the nanoparticles of Bi-deposited TiO_2, showing the significance of the morphology; however, photocatalytic activity is predominantly dependent on the deposition of bismuth. The activity increased by approximately an order of magnitude at the optimum concentration of Bi deposited over TiO_2(2 wt%). The presence of the Bi~((3+x)+) species played a vital role in minimizing electron hole recombination, resulting in higher activity compared to bare TiO_2.     

Open-celled polymeric foam monoliths for heavy metal separations study

Open-celled polymeric foam monoliths prepared by high internal phase emulsion polymerization (HIPE) are being investigated as improved materials for separation of heavy metals. In column flow studies, the foam monoliths have high flow rates and are durable up to at least 40 psi. A 4-vinylpyridine functionality has been incorporated into vinylbenzylchloride/styrene copolymer foams by graft-polymerization of vinylpyridine. The open structure of the foam and the flexible graft-polymerized ion-exchange chains result in improved kinetics in metal uptake. Iron uptake kinetics were greatly increased in the grafted foams over resin beads of similar structure. Plutonium uptake kinetics were moderately increased in the foams.     

Fabrication of sub-micrometer-sized jingle bell-shaped hollow spheres from multilayered core-shell particles

Jingle bell-shaped hollow spheres were fabricated starting from multilayered particles composed of a silica core, a polystyrene inner shell, and a titania outer shell. Composite particles of silica core-polystyrene shell, synthesized by coating a 339-nm-sized silica core with a polystyrene shell of thickness 238 nm in emulsion polymerization, were used as core particles for a succeeding titania-coating. A sol-gel method was employed to form the titania outer shell with a thickness of 37 nm. The inner polystyrene shell in the multilayered particles was removed by immersing them in tetrahydrofuran. These successive procedures could produce jingle bell-shaped hollow spheres that contained a silica core in the titania shell.     

Synthesis and photoluminescence of titania nanoparticle arrays templated by block-copolymer thin films.

High-density arrays of titania nanoparticles were prepared using a polystyrene-b-poly(ethylene oxide) block copolymer (PS-b-PEO) as a template and a titanium tetraisopropoxide based sol-gel precursor as titania source via a spin-coating method. The hydrophilic titania sol-gel precursor was selectively incorporated into hydrophilic PEO domains of PS-b-PEO and form titania nanoparticle arrays, due to a microphase separation between the PS block and the sol-gel/PEO phase. Field emission scanning electron microscopy (FESEM) and scanning probe microscopy (SPM) images showed that the uniformity and long-range order of the titania/PEO domains improved with increasing sol-gel precursor amount. Grazing incidence small-angle X-ray scattering (GISAXS) results indicate that the ordered structures exist over large length scales. Titania nanocrystal arrays of anatase modification were obtained by calcination at 600 degrees C for 4 h. After calcination, separated particles were observed for low and medium amounts of sol-gel precursors. Films with higher precursor amounts showed wormlike structures due to the aggregation between neighboring particles. Removal of the polymer matrix via UV treatment leads to highly ordered arrays of amorphous titania while retaining the domain size and interparticle distance initially present in the hybrid films. Photoluminescence (PL) properties were investigated for samples before and after calcination. The PL intensity increases with the increasing amount of sol-gel precursor. Bands at 412 nm were ascribed to self-trapped exitons and bands at 461 and 502 nm to oxygen vacancies, respectively. Uncalcined or UV-treated samples also showed PL properties similar to calcined samples, indicating that the local environment of the titanium atoms is similar to the environment of the crystalline anatase modification.     

Preparation of microcellular polysiloxane monoliths

Microcellular polysiloxane monoliths were prepared from the continuous phase of a concentrated inverse emulsion. The formulation of the material was adapted to obtain monoliths having structural properties similar to those of common poly(styrene‐co‐divinylbenzene) polyHIPEs. The network was generated by hydrosilylation reaction between a vinylsiloxane crosslinking agent and an oligomeric hydrogenosiloxane. The solids obtained were characterized by mercury porosimetry, nitrogen sorption, and SEM. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 21–32, 2008     

Inorganic Sol-Gel Preparation of Medium Sized Microparticles of Li2TiO3 from TiCl4 as Tritium Breeding Material for Fusion Reactors

Microspheres of Li₂TiO₃ were fabricated by a classical, inorganic sol-gel process from commercially available TiCl₄. Elaborated process consists of the following main steps: (1) dissolving of TiCl₄ in concentrated aqueous HCl and addition of LiOH; (2) formation of sol emulsion in 2-ethylhexanol-1 containing the surfactant SPAN-80 (EH); (3) gelation of emulsion drops by extraction of water with partially dehydrated EH; (4) impregnation of gel to Li:Ti molar ratio MR = 2; (5) thermal treatment at 1200°C in order to receive chloride free product. This temperature can be significantly lowered (to 750°C) by dechlorination starting solution TiCl₄ by chemical treatment of the with nitric acid to form of nitrate-stabilized titania sols. Tritium release from sol-gel made Li₂TiO₃ microspheres were found very close to that observed for other traditional materials, however for the first sample process starts slightly earlier.     

利用改进的本体溶胶-凝胶过程制备单组分二氧化硅单块

溶胶 -凝胶方法具有较低的反应温度 ,可在材料处理的最初阶段即纳米尺度上对材料的结构进行控制 ,所制备材料具有较高均一性和高纯度等优点 ,长期以来引起了众多科学家的关注[1～ 4 ] .然而 ,传统的溶胶 -凝胶工艺存在凝胶时间过长、体积收缩大、形状和尺寸无法控制、严重的龟裂、成本高以及环境污染等缺点 ,限制了其应用 .针对上述问题 ,我们改进了传统的溶胶 -凝胶过程 ,提出本体溶胶 -凝胶技术和复合本体溶胶 -凝胶技术 [1,2 ] .本体溶胶 -凝胶技术由于加入的凝胶促进剂碳酸盐与 Si O2 相容性差 ,存在块体成功率相对较低、表面不光滑和…     

聚合物互通多孔材料的乳液模板法制备及其功能化研究*

本文对近年来利用乳液模板制备聚合物互通多孔材料的研究进行了综述,主要介绍以高内相乳液模板制备互通多孔聚合物整体柱和利用双重乳液 (或称多重乳液) 制备多孔或多空聚合物微球的进展;分析目前多孔聚合物材料研究中存在的问题及其研究动态;讨论合成多孔聚合物材料的性能缺陷及其表面功能化改性的相关研究;并对聚合物互通多孔材料潜在的应用和研究前景进行了展望。     

Fabrication of hydroxyl group modified monodispersed hybrid silica particles and the h-SiO(2)/TiO(2) core/shell microspheres as high performance photocatalyst for dye degradation

The monodisperse hybrid silica particles (h-SiO(2)) were firstly prepared by a modified sol-gel process and the surface was modified in situ with double bonds, then abundant carboxyl moieties were introduced onto the surface of the silica core via thiol-ene click reaction. Afterward, the h-SiO(2)/TiO(2) core/shell microspheres were prepared by hydrolysis of titanium tetrabutoxide (TBOT) via sol-gel process in mixed ethanol/acetonitrile solvent, in which the activity of TBOT could be easily controlled. The carboxyl groups on the surface of silica particles promote the formation of a dense and smooth titania layer under well control, and the layer thickness of titania could be tuned from 12 to 100nm. The well-defined h-SiO(2)/TiO(2) core/shell structures have been confirmed by electron microscopy and X-ray photoelectron spectroscopy studies. After calcination at 500°C for 2h, the amorphous TiO(2) layer turned into anatase titania. These anatase titania-coated silica particles showed good photocatalytic performance in degradation of methyl orange aqueous solution under UV light.