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31.
The influence of nano-particles on CO2 absorption was studied experimentally in a stirred thermostatic reactor. Nano-A1203 and carbon nanotube (CNT) particles which showed different hydrophobic properties were chosen for the investigation. The experimental results were compared with that of micron-size activated carbon (AC) and Al2O3 particles. From the results, no enhancement by micron-size A1203 was found, and with the increase of A1203 concentration, the enhancement factor decreased. However, nano-Al203 showed a weak enlaancement tor me COz absorption. AC and CNT particles all intensified the gas-liquid mass transfer effectively, yet the trend of the enhancement factor with stirring speed for the two particles was different. With increasing stirring speed, the enhancement factor of AC particles was decreased, wl'iereas in CNT suspensions it was increased. The experimental phenomena demonstrated a difference in enhancement mechanism for different size particles. For nano-particles, besides the influence of adsorbability and hydrophobicity, the micro-convection caused by Brownian motion should be also taken into account. Considering the micro-convection effect, a theoretical model was developed to shed light on the absorption enhancement bv nano-oarticles. 相似文献
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叙述了以液相共沉淀法制备纳米磁性Fe3O4粒子的工艺,研究了反应搅拌速度、n(Fe3+)/n(Fe2+)的比例、pH值和熟化温度对制备纳米Fe3O4粒子的影响,并利用透射电镜表征观察Fe3O4纳米粒子的形貌。研究结果表明,在搅拌速度较快的情况下制备纳米级Fe3O4颗粒的最佳合成工艺条件为:n(Fe3+)/n(Fe2+)为1.8∶1(摩尔比),熟化温度70℃,熟化时间30 min,以氨水作沉淀剂最佳pH值是9左右,可制得纯度较高,粒径小于10 nmFe3O4磁性粒子。 相似文献
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Leszek Stobinski Hong-Ming Lin 《过程工程学报》2004,4(Z1):493-495
Careful preparation of the iron nano-particle catalyst for carbon nanotubes (CNTs) fabrication has crucial importance for initial growth of multi-wall carbon-nanotubes (MWCNTs). Thin iron layer was thermally deposited in a high vacuum onto the surface of the SiO2/Si wafer at about 300 K. The sample was heated up to 700℃ in a hydrogen atmosphere, and then the sample was heated once again at750℃ in ethylene atmosphere. After hydrogen treatment continuous Fe layer was changed into many well separated Fe nano-peaks. AFM, SEM and HR-TEM studies of deposited MWCNTs allow us to propose a growth mechanism for long, straight MWCNTs. 相似文献
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储氢蛋壳式纳米金属镍粒子催化剂在苯加氢反应中的应用陈克正,张志琨,崔作林(纳米材料研究所)纳米材料(Nano—structuredmaterials)是由纳米级(10-’m)的小晶粒组成的一种新型功能材料,是本世纪90年代材料科学领域中的一个重大发现... 相似文献
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《Materials and Manufacturing Processes》2007,22(3):366-369
The size of nano particles of ferrites synthesized using low-temperature procedures is sensitive to the chemical reactions. At times, the intermediary stages of chemical reactions remain subtle. It is because of the rate of reactions being fast. Some chemicals which take part in the reaction are playing an autocatalytic role. The understanding of the role played by such reactants is essential for having the control on the reaction and growth size of the particles of the product. FTIR spectroscopic analysis along with DTA can play still a substantial role in the synthesis of nano particles. In this article, the successful use of sol-gel technique with citric acid as the catalysis is analyzed using FTIR and TGA. The individual stages of reaction are explained. 相似文献
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Meta-nitroaniline (m-NA) doped gold/polyvinyl alcohol (Au/PVA) nano-composites are prepared via in-situ reduction of gold salt by employing hydrazine hydrate (HH). Effect of the NLO (non-linear optical) active m-nitroaniline (m-NA) on the photo-physical properties of nano-particles of gold is studied in the colloidal as well as self-supported film form. The UV-Visible absorption bands between 530 and 555 nm due to surface plasmon resonance in Au nano-particles are observed. The absorption values show a shift in the position due to variation in m-NA with respect to the gold concentration. Additional absorption bands are observed after m-NA doping that influences the original position of gold absorption bands. The solutions and the films are further characterized by photoluminescence (PL), FTIR spectroscopy, XRD, TEM and thermal analysis. The particle size as shown by TEM is found to be less than 10 nm. Spin cast nano-composite films show single mode waveguide properties. 相似文献
38.
在含表面活性剂十二烷基硫酸钠(SDS)的低浊(6 NTU)高岭土原水中,投加纳米SiO_2进行动态混凝与静沉试验,借助图像分析技术与定量控制参数,探讨了纳米SiO_2的作用效果与形态学特性.结果表明:絮体的形成与生长具有分形特征,分形结构是影响颗粒混凝、絮团密实度与沉降特性的主要因素;SDS的存在对絮凝初期絮体的形成起阻碍作用,随后SDS与混凝剂的混合体共同对粒子作用,促进絮凝,絮体变大且密实,沉降性能改善;SDS和SiO_2对高岭土粒子存在竞争吸附;单独投加纳米SiO_2时形成的絮体小而脆弱,而以纳米SiO_2为助凝剂能促使PAC絮体结构向更密实的构型转变,对浊度和SDS的去除率提高. 相似文献
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