Preparation and characterization of high-surface-area titanium dioxide by sol-gel process

One of the important ways to improve photocatalytic efficiency is to prepare catalyst with enhanced surface area. In this work, titanium dioxide (TiO₂) nanoparticles having enhanced surface area were synthesized under the interference of SiO₂. The mixed oxide, SiO₂-TiO₂ (10% mol% Si), was prepared by a sol-gel procedure using titanium tetra-n-butoxide as Ti-precursor. The commercial SiO₂ nanoparticles were added into the TiO₂ sols after hydrolysis. After condensation and calcination heat treatment, the SiO₂-TiO₂ nanoparticles were obtained. To achieve the purpose of obtaining the high-surface-area TiO₂, the SiO₂ was removed subsequently by aqueous NaOH solution. The TiO₂ products were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), electron spectroscopy for chemical analysis (ESCA), and by N₂ adsorption-desorption isotherm. A fine mesoporous structure was formed for as-prepared TiO₂ after calcination at 400^°C and the average pore diameter was about 7 nm. The porous TiO₂ products possess mixing phases of anatase and rutile. Phase transformation from anatase to rutile occurred when the samples were calcined. The phase transition temperature is sensitive to the silicon content. The particle size of ～43 nm remained constant upon calcinations from 500 to 700^°C. The specific surface area was increased up to 66% compared to regular TiO₂ samples that were prepared by the similar sol-gel procedure. The porous TiO₂ nanostructures exhibited enhanced photocatalytic performance to decompose methylene blue under UV irradiation.     

Preparation and characterizations of a new PS/TiO2 hybrid membranes by sol-gel process

New organic-inorganic hybrids based on PS/TiO₂ hybrid membranes were prepared by sol-gel and phase inversion process. The membranes were characterized in terms of morphology, structure, hydrophlicity, UF performance and thermal stability. The results showed that macrovoids were nearly suppressed with formation of a sponge like membrane structure. The TiO₂ particles were uniformly dispersed in membrane. The nanodispersed inorganic network formed after sol-gel process and the strong interaction between inorganic network and polymeric chains led to the improvement of porosity and thermal stability. In particular hydrophilicity and permeability increased drastically with the increasing of TiO₂ content in the range of 0-9.3 wt%, without changing retention properties of membrane. However, high-TiO₂ concentration induces nanoparticles aggregate, resulting in the decline of hydrophilicity and permeability. Thus, PS/TiO₂ hybrid membranes with proper TiO₂ content are desirable to meet some specific requirements in industrial separation.     

溶胶-凝胶法制备KH-570改性纳米二氧化钛及其表征

以钛酸丁酯(TBOT)为前驱物,盐酸为催化剂,γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH-570)为改性剂,采用溶胶-凝胶法原位制备了KH-570改性的纳米二氧化钛,研究了KH-570用量对纳米二氧化钛表面改性效果的影响,并采用红外光谱(FT-IR)、X射线衍射(XRD)、粒径分析等手段对纳米二氧化钛进行了表征。结果表明:KH-570接枝到纳米二氧化钛表面,纳米二氧化钛为锐钛矿型;随着KH-570用量的增大,接枝率先上升然后稍有下降,当KH-570用量为TBOT质量的14.57%时,接枝率达到25.6%;与未加KH-570制备的二氧化钛相比,KH-570改性纳米TiO2的平均粒径减小且分布变窄,亲油性得到明显提高。     

Preparation and characterization of titanium dioxide core and polymer shell hybrid composite particles prepared by two-step dispersion polymerization

Titanium dioxide core and polymer shell composite poly (styrene-co-divinylbenzene)-methacrylic acid [P (St-co-DVB)-MAA]] particles were prepared by two-step dispersion polymerization. Fourier transform IR spectroscopy and elemental analysis were used to measure the content of methacrylic acid in composites particles. X-ray measurement photoelectron spectroscopy (XPS) measurements indicated the presence of an MAA unit on the surface of the composite particles. The combined results of the elemental analysis and the XPS measurements showed that the copolymer on the surface of poly (St-co-DVB)-MAA composite particles was rich in MAA compared with that in the interior of the composite particles. Field-emission scanning electron microscopy (FE-SEM) was used to study the morphology characterization. The composite particles produced showing good spectral reflectance compare with bare TiO₂. TGA results indicated that the encapsulation efficiency and estimated density of composite particles. Encapsulation of TiO₂ was up to 87.4% and the density was ranged from 1.78 to 2.06 g/cm³. Estimated density of the composite particles is suitable to 1.73 g/cm³, due to density matching with suspending fluid.     

二氧化钛的疏水改性及其表征

在水相体系中,以二氧化钛为原料,用十六烷基三甲基溴化铵（CTAB）对其进行湿法表面改性。以疏水度为主要考察指标,通过单因素条件实验及正交实验,研究了体系pH值、改性剂用量、改性温度、改性时间等因素对改性效果的影响。结果表明：当体系pH值8、改性剂用量（占二氧化钛总质量的分数）5％、改性时间2．5h、改性温度65℃时,二氧化钛疏水度由13．87％提高至59．89％。     

Preparation and characterization of hybrid nanocomposite coatings by photopolymerization and sol-gel process

Organic-inorganic nanocomposite hybrid coatings were prepared through a dual-cure process involving cationic photopolymerization of epoxy groups and subsequent condensation of alkoxysilane groups. The kinetics of the photopolymerization and condensation reactions were investigated; suitable conditions for obtaining a complete conversion of both reactive groups were found. The obtained films are transparent to visible light. The T_g values of the hybrids increase by increasing the TEOS content in the photocurable formulation. Also, a significant increase in surface hardness could be obtained for the hybrid systems. AFM analysis gave evidence of a strong interaction between the organic and inorganic phase with the formation of silica domains in the nanoscale range.     

Photodegradation of benzothiazole ionic liquids catalyzed by titanium dioxide and silver-loaded titanium dioxide

In recent years, ionic liquids(ILs) have been widely used in extraction, synthesis, electrochemistry and other fields.Meanwhile, the environmental impact of ILs has been attracting a lot of attention, and eco-friendly treatment for ILs is becoming a necessary subject. In this study, photocatalytic degradations of benzothiazole ILs catalyzed by titanium dioxide(TiO_2) and silver-loaded titanium dioxide(Ag/TiO_2) were studied for the first time. The degradation of benzothiazole hexafluorophosphate([C4 Bth]PF6) could reach more than 99% within 240 min with the catalysis of TiO_2. To improve catalytic efficiency, Ag/TiO_2 was synthesized and characterized by UV–Vis diffuse reflectance absorption spectra(DRS) and X-ray photoelectron spectroscopy(XPS). The degradation of [C4 Bth]PF6 could reach more than 99% within 120 min in the degradation catalyzed by Ag/TiO_2. The photodegradation products of benzothiazole ILs are composed of inorganic substances or organic substances with simpler structures, which are easier to decompose and less toxic. The degradation system proposed by this study could provide a simple, green,safe, and economical method for the efficient treatment of benzothiazole ILs.     

Preparation and characterization of multilayer anti-reflective coatings via sol-gel process

Single layer and multilayer films consisting of SnO₂, Ta₂O₅, SiO₂, TiO₂, indium tin oxide (ITO) and antimony tin oxide (ATO) have been prepared by sol-gel dip coating technique. All of the multilayer films contained a SiO₂ top layer, which was composed of SiO₂ nanoparticles. The other films had polymeric character. Obtained films were characterized by ellipsometry, XRD, AFM and SEM. Light transmittance values of the films were compared. Films other than SiO₂ and Ta₂O₅ were found to have crystalline structure. Thickness values of the films were in the range of 30–115 nm and roughness values were in 1.2–23 nm range. Single layer porous silica provided 95% light transmittance, whereas ITO-TiO₂-SiO₂ multilayer film provided a light transmittance of 97.2%.     

Preparation and photoelectrochemical characterisation of electrosynthesised titanium dioxide deposits on stainless steel substrates

TiO₂ films on stainless steel 304 substrates have been prepared from acidic aqueous solutions of TiOSO₄ and H₂O₂ by room temperature potentiostatic cathodic electrosynthesis. Coatings of varied thickness were produced by repeating the deposition step two or three times accompanied by drying steps in between. The resulting gel films were annealed at 400 °C to obtain crystalline TiO₂ (anatase) films with loadings in the 0.1-1 mg cm⁻² range. The deposits had a macro-particulate structure and adhered well on stainless steel 304. The electroactive surface area of the composite electrodes was estimated by cyclic voltammetry in the dark, while their photoelectrochemical behaviour was investigated by photo-voltammetry under UV illumination, both in the presence and absence of oxidizable organics. The effect of deposit thickness on photocurrent and an indicative comparison of electrosynthesised TiO₂/stainless steel 304 photoelectrodes with thermal and particulate TiO₂/Ti electrodes are also presented.     

溶胶-凝胶法制备超细氧化镁陶瓷纤维

以碱式碳酸镁和柠檬酸为原料,采用溶胶- 凝胶法成功制得超细氧化镁陶瓷纤维,并应用红外光 谱仪(FTIR)分析了胶体的形成;应用DSC分析了凝 胶前驱体的热处理过程;通过XRD、SEM分析和观察 了凝胶前驱体纤维及其于450℃热处理后所得到的 超细氧化镁陶瓷纤维的形貌和结构。结果表明:凝胶 的可纺性主要受合成反应溶液中柠檬酸与镁离子物 质的量比、溶液的pH值及搅拌时间的影响,在柠檬 酸与镁离子的物质的量比为2,溶液的pH值在4.0 ～5.0,搅拌时间为16～18h的条件下,制得的凝胶 具有较好的可纺性;凝胶的热分解经历脱水、分解及 氧化镁的形成3个阶段,前驱体凝胶纤维经450℃保 温0.5h处理后,可得到直径均匀,表面光滑、致密的 超细氧化镁陶瓷纤维,其直径可在1μm以下。     

Surface modification on nanoscale titanium dioxide by radiation: Preparation and characterization

Electron beam mutual radiation to induce graft polymerization has been carried out respectively, between nanoscale anatase‐ or rutile‐titanium dioxide particles surface and methyl methacrylate (MMA). The composition and properties of surface modified titanium dioxide were investigated by a number of surface sensitive techniques: X‐ray photoelectron spectrum (XPS), FTIR, X‐ray diffraction (XRD), and NMR. Results of the technological measurements show how surface chemistry is affected throughout the surface modification process, finally leading to a complete and homogeneous vinyl compound overlayer on top of the titanium dioxide samples. In comparison with stereochemical structures of the graft molecular chains and the PMMA induced by radiation polymerization, the surfaces of the oxides are considered to provide a template for the graft polymerization. The grafted titanium dioxide is found to produce a stable colloidal dispersion, in good solvents for the grafted polymer, and the dispersibility of grafted dioxides is influenced by temperature. In addition, the wettability of the surface of titanium dioxide to water is readily controlled by grafting of hydrophilic or hydrophobic polymers. Based on the above results, it is concluded that MMA is covalently linked to the surface of titanium dioxide by a surface modification process. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci, 100: 3510–3518, 2006     

溶胶-凝胶法合成二氧化钛粉末的工艺条件优化

采用sol—gel法合成二氧化钛粉末，通过光催化降解偶氮染料酸性大红G来评价其活性。研究了钛酸四正丁酯(以下简称TNB)的浓度、TNB与水体积之比、pH值和煅烧温度对二氧化钛光催化性能的影响。设计正交试验优化合成二氧化钛的条件。     

负载型TiO2光催化剂的制备及其性能研究

以钛酸丁酯为主要原料，用溶胶-凝胶法在活性炭颗粒表面制备了不同负载次数的负载纳米TiO2。用扫描电镜分析和能谱分析法对负载后的纳米TiO2进行了表征。以亚甲基蓝为降解对象，研究了产品的光催化降解性能。结果表明，随着负载次数的增加，TiO2的负载量增多，负载后的TiO2颗粒呈片层结构，当负载次数太大时，负载颗粒发生团聚，片层结构消失，产品的光催化降解性能下降。负载4次时产品对亚甲基兰的光催化降解效率最高。     

Preparation of zirconia powders by sol-gel route of sodium glycozirconate complex

Zirconia powders were prepared by a sol-gel method, using sodium glycozirconate complex as precursor synthesized via the Oxide One Pot Synthesis (OOPS) process. Gelation of this precursor was achieved through the variation of the hydrolysis ratio without the use of the dopants. The gel samples were also calcined at different temperatures. The resulting zirconia was characterized using X-ray diffraction (XRD), SEM and nitrogen adsorption/desorption. The solid materials obtained after heat treatment at 500 °C by varying the hydrolysis ratio have large surface areas of 154-220 m² g⁻¹ and a narrow pore size distribution in the mesopore region. By variation of the heat treatment, the zirconia xerogels existed in either an amorphous, tetragonal, or monoclinic form at room temperature. Based on XRD data the first identifiable crystalline structure developed from the amorphous phase was the tetragonal polymorph, which was formed between 500 and 800 °C. When the temperature was raised to 1000 °C, zirconia powder with a monoclinic structure was obtained. Surface areas about 280 m² g⁻¹ was obtained after calcination at 400 °C, which drop to ca. 70 m² g⁻¹ following treatment at 1000 °C.     

溶胶-凝胶法制备二氧化钛纳米粉体及掺杂对二氧化钛光吸收的影响

二氧化钛是一种廉价的半导体材料,具有较好的光催化性能,在环境治理、抗菌杀菌以及太阳能电池方面具有重要作用。本文以钛酸四丁酯为原料,采用溶胶-凝胶法制备了二氧化钛粉体,并且探讨了煅烧温度对二氧化钛粉体粒径、晶型的影响。通过粒度分析、XRD分析、扫描电镜分析研究了二氧化钛粒径随煅烧温度的变化规律。同时探讨了掺杂过渡金属离子V5+和稀土金属离子Ce3+对TiO2材料光吸收效率的影响。     

Carbon nanotube/titanium carbide sol-gel coated zirconium diboride composites prepared by spark plasma sintering

With combination of a powder processing technique and a sol-gel process, carbon nanotube/titanium carbide coated zirconium diboride matrix composite was fabricated. Zirconium diboride (ZrB₂) powders were coated with a functionalized carbon nanotubes (CNTs) mixed titanium carbide (TiC) sol-gel precursor. As the results suggests, the carbothermal reduction produced nanosized TiC grains at the surface of the ZrB₂ particles with a homogenous distribution of CNTs. The densification of the CNT/TiC coated ZrB₂ matrix composite was achieved via 1900?°C spark plasma sintering(SPS). The TiC grains and the CNTs were primarily concentrated in the grain boundaries of the ZrB₂ and showed the pinning effects that restrained the growth of ZrB₂ grain. The TiC grain diffusion in the sintering coarsened the grains from nanosizes to 1–2?µm, which improved the densification of the ZrB₂. Due to the difference in coefficient of thermal expansion, CNTs bridged the gaps between the TiC and the ZrB₂ matrix, which formed a weak-bonding interface. The major toughening mechanism found was crack deflection via the TiC grains on the ZrB₂ matrix.     

国内外氯化法钛白粉生产技术的专利分布概况

为了解氯化法钛白粉相关生产技术的知识产权环境,降低企业知识产权风险,采用Innography专利分析平台对国内外氯化法钛白粉生产技术的专利申请进行了统计分析,并重点介绍了该技术在中国的相关专利布局情况。经研究分析发现：氯化法钛白粉生产技术的相关专利申请主要分布在美国、日本、德国、英国和中国;美国杜邦公司在氯化法钛白粉生产工艺的专利技术上有明显的优势;在中国,攀钢集团锦州钛业有限公司在氯化法钛白粉生产技术方面已形成相对完整的专利布局。最后,结合国内情况,给拟发展氯化法钛白粉的企业提出一些参考意见。     

水热法制备TiO2纳米管研究进展

近几年TiO2纳米管在光催化、太阳能电池、环境净化和传感器等方面引起了人们的广泛关注,然而有关水热法制备的TiO2纳米管的化学组成和形成的具体机理尚无定论。笔者综述了目前国内外有关水热法制备TiO2纳米管的组成和形成机理,为水热法制备结构可控的TiO2纳米管提供参考。     

溶胶凝胶法制备平整TiO_2薄膜及其表征

以钛酸四丁酯为前驱体,通过溶胶凝胶法制备表面平整、致密的TiO2薄膜,并且通过热重分析仪(TGA)、X射线衍射仪(XRD)、衰减全反射红外线光谱分析仪(ATR IR)、扫描电子显微镜(SEM)、原子力显微镜(AFM)和接触角测量仪等研究TiO2薄膜的晶相、组成和表面的微观结构、润湿性。利用TiO2薄膜表面部分覆盖的十八烷基三氯硅烷自组装单分子层在紫外光照下的降解来研究其光催化性能,并且用水在该薄膜上的接触角的变化来表征十八烷基三氯硅烷的降解量。研究结果表明:TiO2薄膜具有很低的粗糙度,透明的锐钛矿相薄膜在较弱的紫外光照强度下具有较好的光催化性能,在自清洁和光学薄膜领域有潜在的应用前景。