RuO2/TiO2/漂珠复合光催化剂的制备及性能

"利用RuO2/TiO2前驱体溶胶,采用溶胶-凝胶-浸渍法在漂珠(FP)表面沉积RuO2/TiO2膜,经120 ℃干燥、500 ℃焙烧制备复合光催化剂RuO2/TiO2/FP,并通过SEM、XRD以及FT-IR分别对其结构进行了表征． 结果表明,RuO2/TiO2膜的平均厚度(三层)约1 1m,膜材料中TiO2主要呈现锐钛矿型结构,而RuO2是以非晶态高度分散在粒子表面．以高效氯氰菊酯杀虫剂的光催化降解为模型反应,研究了RuO2/TiO2/FP的光催化性能,探讨了影响催化剂活性的因素及采用太阳光做光源处理     

铁氮共掺杂纳米TiO_2复合膜的制备、光谱分析及光催化活性研究

用溶胶-凝胶法制备铁、氮共掺杂纳米TiO2凝胶,浸渍-提拉法将其镀膜于载玻片表面,经干燥、煅烧,制得Fe-TiO2-xNr复合膜;用XRD,SEM,XPS及UV-Vis对镀膜样品进行了表征.XRD分析表明,Fe-TiO2-xNr膜为锐钛矿结构,少数氮原子替代了TiO2晶格中的氧;SEM照片说明,构成膜的粒子分散均匀,形貌一致,粒径约19 nm:UV-Vis漫反射光谱显示,Fe3+掺杂可使复合膜对可见光的响应红移至740nm处;XPS图谱证明,铁、氮的掺入降低了Ti(2p3/2)电子结合能,从而拓宽了TiO2在可见光区的吸收范围.以光催化降解苏丹红I为模型反应,比较了不同掺杂样品的光催化活性,结果表明,当掺杂的Fe3+相对于Ti4-1的原子比达到0.4%时,复合膜表现出最佳催化性能,4 h后对苏丹红I的降解率达到97%.方法制备的氮和适量铁共掺杂Fe-TiO2-xNr复合膜能协同提高TiO2对可见光的响应能力及光催化活性,在污水处理领域具有潜在的应用价值.     

纳米TiO_2-硅酸铝纤维的制备及光催化脱汞研究

采用溶胶凝胶法以硅酸铝纤维布(fiber)为载体通过不同溶胶配比制备纳米TiO2-硅酸铝纤维(TiO2-fiber)复合物.使用X射线衍射仪(XRD)及场发射扫描电镜(FSEM)等手段对其进行表征;在波长为253.7nm的紫外光(UV)照射下使用复合物进行多种工况下的光催化脱汞试验,验证催化脱汞性能.结果表明,复合物表...     

铂颗粒粒径效应:负载铂纳米颗粒的TiO2薄膜性质研究

制备了负载不同大小Pt纳米颗粒的TiO薄膜。利用TEM测定了Pt粒子的大小,XRD,UV—Vis和测量光电流等方法对TiO2复合膜进行了表征,以亚甲基蓝降解反应评价了Pt／TiO2薄膜的光催化活性。结果表明,在负载相同物质的量的Pt情况下,Pt颗粒的大小直接影响TiO2薄膜的性能,显示较强的粒径效应,当负载平均粒径约5nm的Pt粒子后,薄膜具有最高的光电流和光催化活性。     

纳米TiO2光催化剂防团聚的光谱研究

本文用溶胶 凝胶过程超临界CO2 萃取制备纳米二氧化钛气凝胶 ,用FT Raman ,FTIR ,FS分别对初生态气凝胶粒子、在常态下以气凝胶形式保存了 36 0天的TiO2 纳米粒子及以初生态气凝胶的粉体保存了36 0天的TiO2 粒子进行表征 ,以光催化降解甲基橙为模型反应 ,结果表明 ,在常态下以气凝胶形式保存纳米TiO2 粒子能有效地防止由纳米TiO2 表面超亲水性引起粒子间的团聚 ,保持了初生态粒子的光催化活性。     

不同干燥法制备纳米TiO2光催化剂的光谱研究

本文分别用常态、超临界乙醇和超临界CO2干燥法干燥钛酸正丁酯的醇凝胶，制备纳米TiO2光催化剂。应用XRD，FTIR，FT－Raman和Fluorescent spectrum(FS)等光谱技术对催化剂进行了表征。以光催化降解罗丹明B为模型反应，比较所得样品光催化活性。实验结果表明，不同干燥方法对催化剂的晶相结构、半导体能带结构、光吸收性能、表面性质及光催化活性均产生显著的影响，用超临界CO2干燥法制备的TiO2光催化剂具有较好的光催化活性。     

TiO2薄膜的制备及甲醛的光催化降解

以钛酸四丁酯为前驱体，采用溶胶一凝胶一超声波法制备得到了纳米TiO2溶胶，在单面抛光的硅片上采用旋转涂膜法涂上TiO2溶胶，快速烘干，再经烧结得到TiO2薄膜，并利用XRD，XPS与AFM对其结构性能进行表征，结果表明，膜厚度大约可控在3-5nm，膜表面颗粒大小约20nM，膜的组成主要为锐钛矿型TiO2和少量有机碳化物。在制备TiO2薄膜时，发现膜层随着镀膜次数变化显示不同的颜色差异，并有着良好的对应关系。以此现象入手研究不同颜色的TiO2薄膜在同一光催化条件下甲醛的降解分析，实验结果发现呈蓝色光的TiO2薄膜表现良好的光催化效果，其原因可能是蓝色光对光的吸收较好。     

纳米复合材料TiO2-ZrO2光催化降解可溶性染料的研究

采用溶胶-凝胶方法将光催化剂TiO2和ZrO2复合,再经700℃灼烧5h后获得了纳米复合光催化材料TiO2-ZrO2.该材料经XRD检测具有光催化活性良好的晶型结构.TEM测定结果显示产物的平均粒径约为20nm.通过对可溶性染料刚果红等的光催化降解实验证明,该复合材料具有较高的光催化活性.     

二氧化钛多孔膜的UV-Vis光谱与光催化性能研究

以钛酸四丁酯(Ti(OBu)4)、乙醇胺(MEA)、聚乙二醇(PEG)和无水乙醇为反应体系,采用溶胶-凝胶法制备了TiO2溶胶并通过浸渍提拉法制得了TiO2多孔膜,用UV-Vis,XRD和AFM对制得的多孔膜进行了表征,讨论了薄膜的紫外-可见透过光谱随着薄膜层数的变化规律以及其与膜厚的关系,结果表明在本实验条件下薄膜转移得很均匀,每层膜厚度约为60nm。多孔膜的光催化测试结果表明,随着薄膜层数的增加,光催化活性也逐渐增强,10层多孔膜的光催化活性最高。     

醇热技术制备TiO2纳米晶的荧光光谱及荧光量子产率

采用钛酸四丁酯醇热技术制备了TiO2纳米晶溶胶,透射电子显微镜(TEM)照片显示其为粒径小于10nm的类球形形貌。该纳米晶在最大激发波长375nm激发下,在450nm处产生稳定的强荧光。不同浓度TiO2纳米晶的荧光光谱和吸收光谱表明,该发光带不仅受粒子量子尺寸效应的影响还与带内缺陷能级和表面态的电子跃迁有关,是三者共同作用的结果。以硫酸奎宁在激发波长313nm的荧光量子产率0.55为标准,测得TiO2纳米晶在不同激发波长下的荧光量子产率。结果表明,TiO2纳米晶在激发波长330～370nm范围内有较高的荧光量子产率(约为0.20),远高于文献报道值(10-3数量级)。据此,TiO2纳米晶有望成为一种有前途的无机纳米荧光探针。     

Magnetite ferrofluid with high specific absorption rate for application in hyperthermia

A magnetite ferrofluid coated by dextran with a high specific absorption rate (SAR) of 75 W/g in an AC field of 55 kHz and 200 Oe was prepared by the gel crystallization method with ultrasonic treatment. For comparison, uncoated magnetite particles with a mean diameter of 50 nm were also fabricated. Several possible mechanisms such as Brownian, Neel and diffusion relaxation processes on heating effects and their influence on SAR are discussed. Several factors which can increase the value of SAR were discussed, including dextran coating, ultrasonic treatment, proper particle size and the presence of defects and disorder in the particles.     

基于超声衰减谱的纳米颗粒粒度分布测量研究

利用变声程方式测量纳米颗粒悬浮液的超声衰减谱,以McClements模型和BLBL模型为理论基础,采用最优正则化(ORT)算法,反演得到纳米颗粒的粒度分布。运用该方法,对体积浓度1%的纳米二氧化钛-水悬浊液进行测量,与透射电镜(TEM)图像以及离心沉降纳米粒度分析仪检测结果对比,测量结果吻合较好,表明了利用超声衰减谱方法测量纳米颗粒粒度分布的可行性与可靠性。      

基于AAO模板的TiO2微纳结构及其光电特性

以多孔氧化铝（AAO）和导电玻璃FTO为基底,用射频（RF）磁控溅射法和溶胶凝胶（Sol-gel）法分别制备了微纳结构的TiO₂,两种TiO₂沉积技术各自体现出其特质。从XRD衍射光谱和拉曼散射光谱可以看到,在相同退火条件下,RF和Sol-gel法制备的TiO₂晶相结构不同。在以导电玻璃FTO为基底时,RF制备的薄膜颗粒分布均匀,没有团簇现象;而Sol-gel制备的薄膜由密实的颗粒构成。在以AAO为模板时,Sol-gel制备的TiO₂溶胶粒子由于胶体溶液的流动性使其对孔的填充率保持较高的水平;而RF制备的TiO₂对孔的填充率则降低。光电流实验的结果表明,前者具有更好的光电特性。     

Synthesis and characterization of silica—titania core—shell particles

Abstract Nearly monodispersed particles of silica were prepared and coated with uniform layers of titanium dioxide in anatase phase by hydrolysis and condensation of titanium butoxide. The coating thickness could be altered by adjusting the concentration of reactants (titanium butoxide and water) and the amount of added silica particles. Different coating thicknesses were deposited and studied using optical absorption spectroscopy, electron microscopy and Fourier transform infra-red spectroscopy. It was found that silica particles of size 170 ±5 nm were coated with 23±5 nm thick layer of titanium dioxide. Alternatively titania particles of size 340±5 nm were synthesized by controlled hydrolysis of titanium ethoxide in the presence of sodium chloride. These particles were further coated with 135±5 nm thick layer of silica to investigate changes in properties after changing the shell material     

Modeling and experimental validation of hydrodynamics in an ultrasonic batch reactor

Simulation of hydrodynamics in ultrasonic batch reactor containing immobilized enzymes as catalyst is done. A transducer with variable power and constant frequency (24 kHz) is taken as source of ultrasound (US). Simulation comprises two steps. In first step, acoustic pressure field is simulated and in second step effect of this field on particle trajectories is simulated. Simulation results are compared with experimentally determined particle trajectories using PIV Lab (particle image velocimetry). Effect of varying ultrasonic power, positioning and number of ultrasonic sources on particle trajectories is studied. It is observed that catalyst particles tend to orientate according to pattern of acoustic pressure field. An increase in ultrasonic power increases particle velocity and also brings more particles into motion. Simulation results are found to be in agreement with experimentally determined data.     

Preparation and characterization of low density polystyrene/TiO2 core–shell particles for electronic paper application

In order to reduce the density mismatch between TiO₂ and the low dielectric medium and improve the dispersion stability of the electrophoretic particles in the low dielectric medium for electrophoretic display application, polystyrene/titanium dioxide (PS/TiO₂) core–shell particles were prepared via in-situ sol–gel method by depositing TiO₂ on the PS particle which was positively charged with 2-(methacryloyloxy)ehyl trimethylammonium chloride (DMC). The morphology and average particle size of PS/TiO₂ core–shell particles were observed by transmission electron microscopy (TEM), scanning electron microscope (SEM) and particle size analyzer. It was found that density of PS/TiO₂ core–shell particles were reduced obviously and the particles can suspend in the low dielectric medium of low density. The PS/TiO₂ core–shell particles can endure ultrasonic treatment because of the interaction between TiO₂ and PS. Zeta potential and electrophoretic mobility of the fabricated core–shell particles in a low dielectric medium with charge control agent was measured to be −44.3 mV and −6.07 × 10⁻⁶ cm²/Vs, respectively, which presents potential in electronic paper application.     

A study on measuring distribution of nanoparticle size based on ultrasonic attenuation spectrum

Through varying the ultrasonic path length,the ultrasonic attenuation spectrum of the nanometer particle suspensions is measured.Based on the McClements and BLBL model, the Optimum Regularization Technique is employed to inverse the distribution of particle size for nanometer particles.Experiments are carried out to measure the distribution of particle size of aqueous nanometer titanium dioxide suspension with volume fraction of 1%.The ultrasonic measurement results show good consistence with those from TEM(Transmission Electron Microscope) and centrifugal sedimentation particle size analyzers,which indicate that measuring distribution of the particle size of nanometer particles with the ultrasonic attenuation spectrum is feasible and reliable.     

Ultrasonic effects on titanium tanning of leather

The effects of ultrasound on titanium tanning of leather were investigated. Either 20 or 40 kHz ultrasound was applied to the titanium tanning of pigskins. Five different treatment conditions were carried out and the effects were examined, such as leather shrinkage temperature (T(s)), titanium content and titanium distribution in the leather. Overall heat loading was carefully controlled. Results showed that 20 kHz ultrasound effectively improves titanium agent penetration into the hide and increases the leather's shrinkage temperature. Doubling the frequency to 40 kHz produced negligible enhancements. An impressive 105.6 degrees C T(s) was achieved using 20 kHz ultrasound pretreatment of the tanning liquor followed by 20 kHz ultrasound in the tanning mixture (liquor plus pigskins) in a special salt-free medium. Finally, using a unique ultrasonic tanning drum with 26.5 kHz ultrasound, the T(s) reached a record level of 106.5 degrees C, a value not achieved in conventional (no ultrasound) titanium tanning. The ultrasonic effects on titanium tanning of leather are judged to make a superior mineral tanned leather.     

Synthesis and Characterization of Ag@TiO2 Core-shell Nanoparticles and TiO2 Nanobubbles

Ag@TiO₂ core-shell structured particles of nano-size dimensions have been successfully prepared via a one-step way, which has proved quite effective in procuring stable colloids. Transmission electron microscopy (TEM) was employed to characterize the core size and the shell thickness, which typically were 20~40 nm and ~2 nm, respectively. X-ray diffraction (XRD) indicated the existence of silver. Optical absorption dependence on core size and synthetic temperature has been explored by UV–Vis absorption spectroscopy. Finally, the interesting titanium dioxide nanobubbles with silver core leached out by a unique means, were studied, which consequently proved the core-shell structure of the prepared nanoparticles, confirming the TEM observation.     

Sonochemical-assisted synthesis of nano-structured lead dioxide

PbO(2) nano-powder was synthesized by the ultrasonic irradiation of an aqueous suspension of dispersed beta-PbO, as precursor, in the presence of ammonium peroxydisulfate as an oxidant. The reaction rate increased with an increase in temperature and ammonium peroxydisulfate concentration. In the presence of ammonium peroxydisulfate, the increased concentration of hydroxyl radical facilitated the oxidation of beta-PbO to PbO(2) under ultrasonic irradiation. The PbO(2) nano-powder was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). It was found that the applied ultrasonic wave determines the particle size. PbO(2) samples prepared under optimized experimental conditions have lead dioxide particles in the range of 50-100 nm, as shown by SEM. The XRD results reveal that only beta-PbO(2) is formed under optimum conditions. When the reaction mixture was stirred instead of ultrasonically irradiated, only a fraction of the lead oxide was converted to lead dioxide, and lead sulfate was the main reaction product.