Photooxidation of organic compounds in a solution containing hydrogen peroxide and TiO2 particles under visible light

Cyclohexane was oxidized under visible light in a titanium dioxide suspension containing hydrogen peroxide. Cyclohexanol and cyclohexanone were detected as products. Under similar experimental conditions, nonyl aldehyde was oxidized to nonylic acid. The reaction rate for the oxidation on rutile particles was faster than that on anatase particles. When hydrogen peroxide was added to suspensions of these particles, both rutile and anatase particles became yellow-colored due to the formation of peroxide complexes on their surfaces. The difference between the reaction rates for rutile and anatase particles suggests that the properties of the peroxide complexes formed on these particles are different. The properties of these complexes were studied by UV–vis spectroscopy.     

超声波辐射快速合成过氧化尿素

采用常压超声波辐射技术,利用30%(质量分数)的过氧化氢作为活性氧提供剂,以磷酸二氢钾为稳定剂,用过氧化氢与尿素反应的方法合成过氧化尿素。探讨了过氧化氢与尿素的物质的量比、超声波辐射时间、超声波功率和稳定剂种类对产品收率的影响。得出最佳的反应条件为:过氧化氢与尿素的物质的量比为1.4∶1,反应时间为180 s,功率为300 W,稳定剂磷酸二氢钾用量为1.0 g左右。在此反应条件下,产品的收率可达80%以上,比常规合成产品收率高15%。     

纳米TiO2的制备方法及其应用

介绍了纳米TiO2粉体、薄膜和块材的制备技术，其中对化学法作了较为全面的阐述。同时综述了纳米TiO2在传感器材料、催化剂载体、光催化剂、太阳能电池原料和防紫外线添加剂等方面的应用。     

直接合成过氧化氢Pd/TiO2催化剂的制备

常温和常压下,氢氧直接合成过氧化氢过程中,采用浸渍沉淀法制备Pd/TiO₂催化剂。考察了pH、搅拌时间t₁、静置时间t₂及焙烧温度等制备条件对催化剂活性的影响。正交实验结果表明,影响催化剂活性的顺序为：pH＞搅拌时间＞焙烧温度＞静置时间。在pH=8、t₁=0、t₂=0和（250～300）　℃焙烧3 h的条件下,制备的催化剂活性最好。     

Preparation of Li2TiO3 by hydrothermal synthesis and its structure evolution under high energy Ar+ irradiation

Ultrafine lithium titanate (Li₂TiO₃) powder was synthesized by hydrothermal method. The phase formation and transition condition among α, β, and γ-Li₂TiO₃ were discussed. XRD and ICP-AES showed the single α-phase was formed at 180 °C with 2 h hydrothermal reaction, and it transited into β-phase at 400 °C. SEM observation and EDS analysis confirmed the dissolution of TiO₂ and the formation of α-Li₂TiO₃ proceeded simultaneously with preferable growth direction of (-133) lattice. During the phase transition, the powder maintained the small crystallite, which facilitated the fabrication of Li₂TiO₃ bulk with small grain size. After the Ar⁺ irradiation, the surface region to the depth of 3 μm of Li₂TiO₃ ceramic was affected, where the decrease of crystallization and disturbance of short-range order were confirmed by GIXRD and Raman spectroscopy. In spite of the structure change at the surface area, the ceramic bulk maintained the same.     

以硫酸氧钛为原料制备纳米二氧化钛

纳米二氧化钛是一种重要的新型无机功能材料，其制备及应用愈来愈受到重视。以硫酸法生产二氧化钛的中间产物——硫酸氧钛和偏钛酸为原料制备纳米二氧化钛粉体，具有原料来源广泛、价格低廉、有利于工业化生产等优点，是大规模制备纳米二氧化钛粉体的重要途径。重点对沉淀法、胶溶法、水热法制备纳米二氧化钛的工艺及特点进行了介绍，对工业化生产存在的问题及解决方法进行了讨论。     

电位滴定法测定过氧化氢溶液中的过氧化氢含量

利用自动电位滴定仪测定过氧化氢溶液中的过氧化氢含量,研究了仪器的最佳操作条件及方法的准确度和精密度.结果表明:采用电位滴定法,在自动电位滴定仪自动找终点、等量滴定及搅拌速率为8 r/s的条件下测定过氧化氢溶液中的过氧化氢含量,其相对误差为0.10％,相对标准偏差为0.39％,测定1个试样耗时为683 s左右;在电位滴定...     

超声波和微波联合辐照下铁酸锌的制备

在超声波辐照下共沉淀法得到铁酸锌前驱体,然后在微波辐照下焙烧得到脱硫剂的活性组分铁酸锌。考察了不同焙烧温度和不同焙烧时间对铁酸锌晶相和粒径的影响。实验结果表明,超声波共沉淀法制备铁酸锌是可行的,且在微波辐照下得到的铁酸锌晶相更完整、晶体粒子更为均匀,同时大大缩短了焙烧时间;在700℃下微波焙烧1 h所形成的铁酸锌能较好地满足作为脱硫剂活性组分的要求。     

纳米氧化钛氧化硅复合光催化剂的制备及表征

以硅酸钠、硫酸钛为原料，添加乙二醇单甲醚，采用沸腾回流水解法，制备出二氧化钛-二氧化硅复合光催化剂。讨论了二氧化钛-二氧化硅复合光催化剂的最佳制备条件，并用XRD、XPS、TEM、BET等手段对样品进行了表征。结果表明，所制备的二氧化钛-二氧化硅复合光催化剂，由锐钛矿型二氧化钛和无定型二氧化硅组成，粒径在10nm左右。     

Sonocatalytic damage of bovine serum albumin (BSA) under ultrasonic irradiation by mixed TiO2/SiO2 powder

BACKGROUND: In order to effectively damage some biomolecules under ultrasonic irradiation, a mixed TiO₂/SiO₂ powder with high catalytic activity and selectivity was used as a sonocatalyst. RESULTS: The mixed TiO₂/SiO₂ powder heat treated at 450 °C for 30 min was adopted as a sonocatalyst and the damage to BSA molecules under ultrasonic irradiation was assessed. In addition, the effects of such variables as molar ratio of TiO₂ and SiO₂, treatment temperature and time, ultrasonic irradiation time, catalyst amount, solution acidity, ionic nature and strength, ultrasonic irradiation power and D₂O concentration on the damage to BSA molecules were studied by means of UV‐visible and fluorescence spectra. The results showed that the degree of damage was aggravated by an increase in ultrasonic irradiation time, catalyst amount, solution acidity, ultrasonic irradiation power and D₂O concentration, but was reduced by an increase in ionic strength. CONCLUSION: The results indicated that the mixed TiO₂/SiO₂ powder displayed higher activity and selectivity compared with nano‐sized TiO₂ and SiO₂ powders during the sonocatalytic damage of BSA. The extent of the damage decreased in the order TiO₂/SiO₂ > nano‐sized TiO₂ > nano‐sized SiO₂. These results are of great significance for applying sonocatalytic methods to treat tumours. Copyright © 2008 Society of Chemical Industry     

Preparation and characterization of optically active poly(amide-imide)/TiO2 bionanocomposites containing N-trimellitylimido-L-isoleucine linkages: using ionic liquid and ultrasonic irradiation

In the present investigation, novel poly(amide-imide)/TiO₂ bionanocomposites containing L-isoleucine moiety in the main chain were prepared via a simple and inexpensive ultrasonic irradiation process. Poly(amide-imide) as a source of polymer was synthesized by direct polycondensation reaction of N-trimellitylimido-L-isoleucine with 4,4′-diaminodiphenylsulfone in the tetrabutyl ammonium bromide/triphenyl phosphite as a green solvent system. Due to the high surface energy and tendency for agglomeration, the surface of TiO₂ nanoparticles was modified with γ-aminopropyltriethoxyl silane. The resulting hybrid bionanocomposites were fully characterized by FT-IR spectroscopy, UV–vis spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy (TEM) and thermogravimetric analysis. Through TEM photographs, it can be found that the surface modified TiO₂ nanoparticles with diametric size of less than 40 nm, uniformly dispersed in the obtained PAI matrix.     

Preparation of TiO2 epoxy nanocomposites by ultrasonic dispersion and resulting properties

Nanocomposites gained more and more importance in the last few years because of their improved performance over the neat polymer matrix, that is, toughness and stiffness can be enhanced simultaneously by the addition of nanoparticles. However, the dispersion of these particles in the matrix remains a big challenge. In this study, two types of TiO₂ nanoparticles were dispersed in two different epoxy resins by means of ultrasound. The particle size development in dependence on the dispersion time was investigated by dynamic light scattering for the different material systems. Furthermore, the influence of the viscosity on the sonication process' efficiency was analyzed. The resulting nanocomposites were tested for fracture and Charpy toughness. SEM images revealed that the improved fracture toughness properties are correlated to a rougher fracture surface, whose formation dissipates more energy. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

溶胶-凝胶法制备纳米二氧化钛及其对苯酚的光催化性能研究

以钛酸丁酯为原料,用溶胶-凝胶(Sol-gel)法制备了纳米TiO2粉末。采用透射电子显微镜和X光衍射仪对粉体的粒径、物相、形貌和热稳定性进行了表征。通过粉体对苯酚的降解情况对其光催化活性进行了测试,结果表明TiO2具有良好的光催化氧化性能。     

微波辐射法研制复合半导体光催化材料TiO2/ZnO

采用微波辐射法制备了复合型半导体光催化材料TiO2/ZnO,利用X射线衍射(XRD)测试技术对TiO2/ZnO复合型半导体光催化材料进行了表征。用甲基红模拟有机废水,在高压汞灯模拟日光光照的条件下,研究了复合型半导体光催化材料TiO2/ZnO光催化降解有机废水的过程,并在相同的条件下,与机械研磨法制备的复合型半导体光催化材料TiO2/ZnO的光催化性能进行了对比实验。研究结果表明,微波辐射法制备的复合型半导体光催化材料TiO2/ZnO具有很好的光催化性能,TiO2/ZnO投加量为0.5g.L-1时,其具有良好的光催化脱色性能,经1h光照,对甲基红的光降解效率可以达到100%。随着溶液初始浓度增加,甲基红的降解率增大。     

WS2 sensitized mesoporous TiO2 for efficient photocatalytic hydrogen production from water under visible light irradiation

Nanosized WS₂ sensitized mesoporous titanium dioxide (TiO₂) was prepared to extend the adsorption of the wide band gap TiO₂ into visible light region. Compared with TiO₂ substrate without mesopores, it was found that the mesoporous substrate is beneficial for larger amount of WS₂ loading and inhibition of the light-induced detachment of WS₂ particles from the substrate during photocatalytic reaction, which leads to higher photocatalytic activity and better stability. We also found that the rate-determining step for photocatalytic hydrogen production is the transfer of electrons from TiO₂ substrate to H⁺ in solution, when the recombination between electrons and holes within TiO₂ could be neglected. In this case, deposition of Pt at the surface of semiconductor is indispensable for efficient hydrogen production.     

纳米TiO_2的制备、表征及光催化降解酸性品红

以钛酸四正丁酯为原料,采用溶胶-凝胶法制备了纳米TiO2粒子,对其进行了TG-DTA,XRD,TEM和BET分析,并分别在紫外光和可见光下考察了其光催化降解酸性品红性能。结果表明,自制的纳米TiO2对酸性品红具有很好的光催化降解脱色能力,500℃的样品在紫外光下,20 min内即可将200 mg/L的酸性品红溶液完全降解脱色,在可见光下,210 min内酸性品红的脱色率达80%。     

蒽醌法生产过氧化氢工作液中的四氢蒽醌

蒽醌法生产过氧化氢工作液中的四氢蒽醌含量对过氧化氢生产操作影响很大。通过对四氢蒽醌产生的原因和其物理、化学性质的分析,通过对四氢蒽醌在生产中的氢化、氧化反应原理的分析,通过对各个生产装置开车及运行情况的考察和对比,总结了四氢蒽醌在工作液循环中产生的规律,即四氢蒽醌含量的多少受催化剂、载体和溶剂、操作条件及活性氧化铝的影响,阐明了四氢蒽醌在生产中的作用及含量的高或低的利与弊,提出了控制其含量过高的方法。     

The reduction of hydrogen peroxide at an Au-coated nanotubular TiO2 array

An Au-coated TiO₂ nanotubular array, in the vertically aligned form, was investigated as a highly porous nanostructured electrode for the electrochemical reduction of H₂O₂ in an acidic sulphate electrolyte at 295 K. The TiO₂ nanotubular arrays were formed via a two-stage anodising then nanosized Au particles were sputter deposited onto the surface. The following aspects were studied: (a) the shape evolution of Au particles on the nanotubular array (via surface microstructural imaging), (b) the effect of different degrees of Au loading on the nanotubular array (via voltammetric analysis) and (c) the electrochemical response of an Au–TiO₂ nanotubular array compared to a plain, 2-D Au foil. The Au particles could be deposited as a thin 3-D coated layer or as nodular nanostructures on the array. The highly nanoporous structure of the Au–TiO₂ electrode led to a large enhancement in the limiting current (enhancement factor up to 6.6) and charge density (enhancement factor up to 8.9) for peroxide reduction compared to a plain Au foil due to the architecture of the ordered, high surface area of the nanotubular array.     

Metronidazole photodegradation in aqueous solution by using photosensitizers and hydrogen peroxide

BACKGROUND: The effectiveness of UV radiation on the indirect photodegradation of metronidazole (MNZ) conducting a kinetic study of the process in the presence of radical promoter (H₂O₂) and photosensitizer (Sens) promoters (duroquinone, tetrahydroxyquinone, tetrachloro‐1,4‐benzoquinone, 4‐carboxy‐benzophenone, 2,4‐dihydroxybenzophenone, 4‐hydroxybenzophenone, and 4,4′‐dihydroxybenzophenone) was investigated. RESULTS: The electron‐donating groups of photosensitizers may favor MNZ photodegradation through electron transfer. However, the photosensitizers studied showed low effectiveness of MNZ photodegradation in aqueous phase. The presence of H₂O₂ substantially increased MNZ photodegradation rate, which was enhanced by increasing the concentration of hydrogen peroxide in the system. The contribution of direct photolysis of MNZ in the UV/H₂O₂ system was drastically decreased with increasing H₂O₂ concentrations. CONCLUSIONS: The low effectiveness obtained with most of the Sens used demonstrates that metronidazole cannot be photoxidized by indirect photooxidation in aqueous solution. Copyright © 2012 Society of Chemical Industry     

Preparation of GaP/RhB nanocomposite by ultrasonic irradiation

The GaP/rhodamine B (RhB) nanocomposite was synthesized by ultrasonic irradiation method and characterized by transmission electron microscope, Fourier transformation infrared spectroscopy and Raman spectroscopy. The results show that the morphology of GaP/RhB nanocomposite changed from “superlattice” to asymmetric core-shell and finally to symmetric core-shell microstructure with the extending of irradiation time. The possible reason for the changing of morphology of GaP/RhB nanocomposite was investigated.