反应性聚硅氧烷微乳液的合成研究

采用微乳液聚合法,以八甲基环四硅氧烷(D4)、γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH-570)为原料,合成半透明的反应性聚硅氧烷微乳液,研究了聚合工艺因素对单体转化率、乳液透射率、粒径及乳液稳定性的影响。结果表明,当D4用量为10%,DBSA用量为12%(占D4),KH-570用量为6%(占D4),乳化剂SDS、AEO-7、AEO-9按质量比4∶2∶1复合,用量为6%,助乳化剂正丁醇用量为0.5%,温度为80~85℃,反应时间为5 h时,所制备的反应性聚硅氧烷微乳液单体转化率可达85.63%,外观半透明,无漂油,粒径在40~50 nm。     

Nanosized TiO2 synthesis by EbCDAB microemulsion

BACKGROUND: Microemulsion is the easiest and cleanest of the popular methods of synthesizing nanomaterial. This work investigated the possibility of forming a single‐phase microemulsion using ethanediyl‐α,β‐bis (cetyldimethylammonium bromide), termed EbCDAB, in a n‐hexanol/water system, and looked for the best scale of microemulsion to synthesize TiO₂ to give the best cleaning of organic pollution. RESULTS: Results confirm that EbCDAB, n‐hexanol and water form a microemulsion system, and this system is an effective way to synthesize nanoparticles of TiO₂. Photo catalysis experiments showed sample E_6?3 to be the best catalyst, and it decomposed 82% of Methyl Orange (10 mg L^?1) in 60 min under UV‐light irradiation. E_6?3 had 1.4 times higher activity than the commercial P25. Analyses using transmission electron microscopy (TEM), X‐ray diffraction (XRD), thermographic differential scanning calorimetry (TG‐DSC) and Fourier transform infrared microscopy (FT‐IR), showed that particles of E_6?3 were of size around 11 nm and of anatase phase. CONCLUSION: The best microemulsion was found to have weight ratio n‐hexanol:EbCDAB:water of 6:3:1. At this ratio, TiO₂ nanoparticles were easily produced. Copyright © 2010 Society of Chemical Industry     

Structural stability of photodegradable poly(l-lactic acid)/PE/TiO2 nanocomposites through TiO2 nanospheres and TiO2 nanotubes incorporation

Photodegradation of PLA/PE, PLA/PE/TiO₂ nanospheres and PLA/PE/TiO₂ nanotubes was obtained under simulated sunlight. The nanocomposites were analyzed by infrared spectroscopy, scanning electron microscopy and tensile-deformation measurements. TiO₂ nanospheres and TiO₂ nanotubes were found to present different effects on the crystallinity of PLA and a straight correlation between structural organization and photostability was observed. According to the results, TiO₂ promotes the degradation of PLA and PE, affecting the organizational level of the polymers. By adding TiO₂ nanoparticles to the PLA/PE films, vibration modes characteristic of degradation products were promptly observed and the lifetime of the polymer decreased when compared to the PLA/PE without TiO₂ nanoparticles. Mechanical measurements showed an improvement of the mechanical properties when adding the TiO₂ nanoparticles.     

沉淀法合成高纯超细氢氧化镁的研究

以工业氯化镁、氨水为前驱体,在水－乙醇体系下合成了粒度为100－200nm的氢氧化镁超细粉体。研究了水与乙醇的比例对粉体颗粒形貌、粒度、Mg^2 沉淀率的影响。研究发现,适量乙中以提高Mg^2 沉淀率,并抑制晶体的单向生长,但乙醇浓度过高使得产物的分散困难,合适的乙醇与水的比例为1：2－1：1。     

沉淀法制备纳米白炭黑工艺参数的控制

在沉淀法制备纳米白炭黑的实验过程中,调整酸的质量分数、反应体系的温度、pH值、原料参数等,同时严格控制陈化时间、酸滴加速度等合成条件,优化制备工艺参数,得到粒径小、品质好的纳米白炭黑。利用X-ray衍射仅和扫描电镜分析研究了白炭黑的结构。     

Single-step synthesis of N-doped TiO2 by flame aerosol method and the effect of synthesis parameters

We have established a novel route for the synthesis of N-doped TiO₂ by adopting flame aerosol (FSP) technique and investigated the effect of water content on the physico-chemical properties of the as-synthesized nanoparticles. The key characteristics of the developed method are to modify the precursor solution in order to incorporate nitrogen atoms into the TiO₂ lattice without altering the FSP set-up. The reduction of the flame enthalpy resulting in N-incorporation into the TiO₂ and the N-doping can be greatly enhanced further by the addition of secondary N-source (urea). Our XRD results reveal a shift of the (101) plane anatase diffraction peak to lower angles in our N-doped TiO₂ compared to undoped TiO_2, which suggest the distortion and strain in the crystal lattice prompted by the incorporation of the nitrogen atoms. The growth or expansion of crystal lattice can be attributed to the larger atomic radius of respective nitrogen atoms (r?=?1.7 Å) compared to oxygen (r?=?1.40 Å). Our XPS and EDX spectroscopy results elucidate that the nitrogen was effectively doped into the crystal lattice of TiO₂ in our as-synthesized N-TiO₂ catalysts predominantly in the form of interstitial nitrogen (Ti?O?N). The nitrogen atoms incorporation into the crystal lattice of titania modifies the electronic band structure of TiO₂, resulting in a new mid-gap energy state N 2p band formed above O 2p valence band. This occurrence narrows the band gap of TiO₂ (from 3.12 to ～2.51?eV) in our N-doped TiO₂ and shifts the optical absorption to the visible region.

Copyright © 2018 American Association for Aerosol Research     

Effect of deposition parameters on properties of TiO2 films deposited by reactive magnetron sputtering

TiO₂ films were grown onto unheated 5083 aluminum alloy substrates by reactive magnetron sputtering from a pure Ti target in Ar-O₂ gas mixture in different power, bias voltage, Ar/O₂ ratio and deposition time at room temperature. The effects of different deposition parameters on the structure and properties of TiO₂ films were investigated systematically by field emission scanning electron microscope (FESEM), atomic force microscope (AFM), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), nanoindentation tests, electrochemical tests and antibacterial tests. The results show that power and bias voltage are two main factors to affect the structure and properties of TiO₂ films during the sputtering process. XRD results show that anatase phase is the main phase of the film, and the enhanced content of anatase phase with the increase of sputtering power and bias voltage. Nanoindentation tests exhibit that higher H/E (Hardness/Modulus) ratio can be achieved by depositing TiO₂ film. And the corrosion resistance and antifouling property are all improved after depositing TiO₂ film. 2# sample shows the optimal corrosion resistance, E_corr and I_corr are −0.27388 V and 3.7232 μA/cm², respectively. 1# sample exhibits excellent antibacterial property, the d ensity of bacteria is only 217 cell / mm², which is 484% higher than that of uncoated matrix.     

A low-temperature combustion synthesis process for production of Ti from TiO2

Calciothermic reduction of titanium dioxide is suggested as an alternative to the conventional Kroll process for production of metallic titanium. In this study, a simple reactor was used to carry out the reaction of TiO₂ with 20 wt % excess Ca at 1000°C to obtain titanium product with a mean size of Ti particles around 20 μm. A sharp decrease in reaction temperature can be achieved by using KClO₄ as an additive. In this case, sub-micron agglomerated titanium particles were obtained.      

On the effects of the sol-gel synthesis parameters on textural and structural characteristics of TiO2

The effects of alcohol/alkoxide, water/alkoxide molar ratios, acid addition, type of solvent, reaction temperature and calcination temperature on textural, structural and morphological characteristics of TiO₂ were studied. The results show that surface area, pore size distribution and crystalline phases were very sensitive to preparation conditions.     

水杨酸-2-乙基己酯合成工艺研究

以水杨酸、2-乙基己醇为原料,对甲苯磺酸为催化剂,直接反应合成了水杨酸-2-乙基己酯,并用折光率、红外光谱对产物进行了表征.研究了水杨酸与2-乙基己醇物质的量比、催化剂用量、反应温度、反应时间对酯化率和产物收率的影响.得出的最优反应条件为:n(水杨酸)∶n(2-乙基己醇)为1:3,催化剂对甲苯磺酸的质量分数为水杨酸的1...     

The effect of plasma electrolytic oxidation process parameters on the tribocorrosion properties of TiO2 coatings

Despite the fact that Titanium and its alloys are materials which have excellent corrosion-resistant properties, they have poor wear and friction performance under tribological conditions. The aim of this study is to find suitable parameters for the surface treatment of Cp-Ti substrates which are used under saline environment. In this study, TiO₂ coatings were grown on Cp-Ti substrates at different frequencies which are parameters of the coating process. Due to its low cost and ability to achieve high thicknesses, The Plasma Electrolytic Oxidation (PEO) method was applied to grow TiO₂ coatings. The microstructures, morphology, and crystallographic structure were analyzed using SEM and XRD. Tribocorrosion properties of the coatings were investigated using a combination of the pin-on-disk wear test and potentiodynamic polarization test units. The frequency is known to have a strong impact on the PEO process. The impacts of frequency changes on the PEO coating performance were examined under a constant voltage. As result, the increase of the frequency caused smaller pores and cracks in the surface morphology of the coating and at the same time this yielded an increment on the tribocorrosion behavior of the coating.     

纳米二氧化钛有机化改性工艺研究

研究并筛选了最佳表面改性剂。对以月桂酸钠作改性剂进行了改性机理的探讨和工艺条件的研究,并对有机化纳米二氧化钛作了红外光谱（IR）和透射电镜（TEM）测试。     

纳米TiO2薄膜对活性深蓝ST-2GLN染料的光催化降解研究

采用溶胶-凝胶（Sol—Gel）法,以钛酸正丁酯为前驱体,以不锈钢表面为基底,用提拉法镀膜,在400℃下高温煅烧2h．制备出纳米TiO,薄膜光催化剂。在以波长为254nm、8W的紫外灯为光源、光源到溶液的距离为2cm的条件下。对活性深蓝ST-2GLN模拟染料废水进行光催化降解试验。探讨了光照时间、初始质量浓度、TiO2提拉层数、初始pH值和H2O2的投加量等因素对脱色率的影响。结果表明：初始质量浓度为80mg／L、TiO2提拉层数为4层、pH值为7．0的条件下,H2O2（30％）的投加量为3．0mL,经2h的光照,脱色率达到87％。光催化降解活性深蓝ST-2GLN染料的动力学研究表明．其降解过程是一个一级反应过程,反应速率常数为0．0132min一。     

微乳液法制备Fe3O4/TiO2磁性纳米粒子

采用多元醇还原法制备出平均粒径为6.0 nm的Fe3O4磁性纳米粒子,以此磁性纳米粒子为核,在OP-10/正丁醇/环己烷/浓氨水反向微乳体系中制备出Fe3O4/TiO2磁性纳米复合粒子,通过XRD,TEM,VSM对复合粒子进行性能表征。结果表明,采用微乳液法能够制备出Fe3O4/TiO2磁性纳米复合粒子,并且包覆后比饱和磁化强度有所下降,但矫顽力仍趋近于0,显示超顺磁性。     

Selective synthesis of TiO2 nanopowders

Nanosized anatase, rutile, brookite, and mixtures of these materials taken in different ratios are synthesized using the detonation method with variations in the densities and ratios of explosives composed of the TiO₂ precursor, NH₄NO₃, and C₃H₆N₃(NO₂)₃. It is shown that the phase composition, the phase content, and the average particle size of TiO₂ nanopowders depend on the composition of the explosive mixtures and their densities. When the weight ratio between the C₃H₆N₃(NO₂)₃ compound and the TiO₂ precursor lies in the range 0.695–1.270, the average size of rutile particles is larger than that of anatase particles by a factor of approximately two.     

Single-step synthesis process of interconnected spiderweb-like TiO2 films as photoanode for self-powered ultraviolet-detector

Anatase TiO₂ films with tunable nanoarchitectures were fabricated directly on conductive substrates using one-step electrostatic spray deposition (ESD). The morphology of TiO₂ films gradually evolved from one-dimensional (1D) rice-like to three-dimensional (3D) interconnected spiderweb-like architecture by only varying the flow rate of precursor solution with no need for templates or binders. The synergistic integration of the unique morphology and higher crystallite size imparted 3D-interconnected nanospiderwebs with remarkably enhanced photoconversion efficiency (6.52%) compared with commercial TiO₂ and other 1D nanoarchitectures. The self-powered ultraviolet (UV)-photodetector based on nanospiderwebs showed high photosensitivity (405300%), fast response and excellent photosensitivity linearity in a wide light intensity range. This self-powered device is a promising candidate for high-sensitivity and high-accuracy UV photodetectors.     

Heat-integrated reactive distillation process for synthesis of fatty esters

Catalytic reactive distillation (RD) offers novel opportunities for manufacturing fatty acid alkyl esters involved in specialty chemicals and at a larger scale in biodiesel. The integration of reaction and separation into one RD unit, corroborated with the use of a heterogeneous catalyst, provides major benefits such as low capital investment and operating costs. This work presents a novel heat-integrated process based on reactive distillation that aims to reduce furthermore the energy requirements for biodiesel production, leading to competitive operating costs. Despite the high degree of integration, the process is well controllable using an efficient control structure proposed in this work. Rigorous simulations embedding experimental results were performed using computer aided process engineering tools, such as AspenTech Aspen Plus and Aspen Dynamics. The RD column was simulated using the rigorous RADFRAC unit with RateSep (rate-based) model, and explicitly considering three phase balances. Steady-state and dynamic simulation results are given for a plant producing 10 ktpy fatty acid methyl esters (FAME) from methanol and waste vegetable oil with high free fatty acids (FFA) content, using sulfated zirconia as green catalyst. The heat-integrated RD process eliminates all conventional catalyst related operations, efficiently uses the raw materials and the reactor volume offering complete conversion of the fatty acids and allowing significant energy savings. Remarkably, compared to previously reported RD processes, the energy requirements of this process are about 45% lower - only 108.8 kW h/ton biodiesel - while the capital investment cost remains the same as no additional equipment is required.     

Functionalization of wood particles through a reactive extrusion process

Wood particles were modified in a reactive extrusion process with maleated polyethylene (MAPE) and maleated polypropylene (MAPP) compounds. Contents of MAPE were varied to study the effect of material composition on grafting efficiency during reactive extrusion, while extruder barrel temperatures and rotational screw speeds were varied to evaluate the effects of processing conditions on the modification of wood particles. Polymer molecular weight effects were followed using MAPP, with different molecular weights. Efficiency of the modification was assessed using FTIR and XPS surface analysis techniques, along with a titrimetric analysis, to verify the esterification reaction between the wood particles and maleated polyolefins. The grafting of maleated polyolefins onto the surface of the wood particles through a reaction of the hydroxyl groups on the wood surface with the maleated groups of the maleated polyolefins was confirmed, while the level of grafting of MAPE onto wood particles was determined to be a function of the MAPE concentration. However, there was no significant difference found in grafting efficiency at different extrusion processing conditions, rather all of the conditions resulted in adequate grafting. Similarly, there was no difference in grafting efficiency with the molecular weight of MAPP. Reactive extrusion was found to be a suitable technique for the modification of wood particles, with maleated polyolefins, for all of the material compositions and processing conditions studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3131–3142, 2006     

纳米TiO2光催化处理采油废水研究

纳米二氧化钛为光催化剂,UV为光源,对采油废水进行光催化降解处理。考察了初始pH值、光照时间、催化剂投加量及H2O2与Fe3 因素对采油废水光催化处理效果;用XRD和SEM等分析方法对催化剂进行了微观结构分析表征。结果表明:在0.5%催化剂的投加量、pH=6的反应体系和50min的光照时间,达到最大COD去除率7.2%。     

Numerical study on particle size distribution in the process of preparing ultrafine particles by reactive precipitation

Based on the population balance and mass balance in a reactive precipitation process, a numerical simulation model was developed to predict the particle size distribution (PSD) in the reactive precipitation process. The precipitation system of BaCl₂ with Na₂SO₄ to prepare BaSO₄ in aqueous solution was adopted to obtain ultrafine particles in a stirred precipitation reactor and the particle size distribution and the morphology of the particle were observed under transmission electron microscope. It was illustrated by the experimental observation of the micrographs of BaSO₄ particles obtained that apparent agglomeration occurred between the particles, which phenomenon must be taken into consideration in PSD modeling. The population balance equation was calculated by discretization method to obtain particle number and particle size distribution. By implementing the model, the reactive precipitation process in a batch reactor including reaction, nucleation, growth and agglomeration was simulated. The simulation results were validated by the experimental data of BaSO₄ precipitation. Further analysis was endeavored to explore the effects of some important factors such as the supersaturation degree and agglomeration on the evolution of the volume-based characteristic particle size and the variance of volume-based characteristic size of the particles. It was depicted that particle size and particle size distribution are controlled by the supersaturation degree and agglomeration between the particles. Stemming from the analysis in the context, the disciplinarian of the influences of these factors and the method for controlling particle size distribution were presented for the reactive precipitation process.