Wet Chemical Synthesis of Hydroxyapatite Particles from Nonstoichiometric Solutions

Hydroxyapatite [Ca₁₀(PO₄)₆(OH)₂; or HAp] particles with controlled stoichiometry were precipitated from solution by forced hydrolysis of mixtures of calcium and phosphate salts at a high pH and temperature. The mixing procedure determines the final stoichiometry of the precipitated HAp. The resulting panicles were characterized by FTIR, XRD, TEM, and light scattering and their chemical composition was determined by ICP, indicating that pure crystalline HAp with a narrow size distribution was indeed formed, despite some aggregation being detected by light scattering. The Ca/P ratio was found to depend on the specific preparation route.     

熊果醛和齐墩果醛的合成及其表征

为了开发具有抗炎和抗β淀状蛋白质诱导神经毒性的三萜类化合物,一些新的齐墩果酸和熊果酸衍生物通过碳-28位羧基的修饰而被合成。相关化合物的结构通过IR、^1h NMR和^13C NMR进行了表征。     

SiO2空心微球的制备与表征

以自制的微米级碳酸钙颗粒为模板,正硅酸乙酯为硅源,通过溶胶-凝胶方法合成出CaCO3/SiO2核壳结构;随后通过高温煅烧、酸浸和干燥处理,制备出圆形度高、分散性好、结构完整的微米级SiO2空心球。并利用SEM、XRD、FTIR、TG和压缩实验等方法对空心微球的形貌、结构和抗压强度进行了分析和测定。SiO2空心微球的粒径为2-5μm,壳层厚度为0.42-0.85μm,比表面积为554.01m^2/g,最可几孔径为1.7nm,抗压强度在20~30MPa之间。     

Synthesis of hydroxyapatite on titanium coated with organic self-assembled monolayers

The work focuses the formation of hydroxyapatite (HA) layers from simulated body fluids (SBF) onto titanium coated with NH₂-, SH-, and SO₃H-SAMs, respectively, at room temperature and 37 °C as well as pH values of SBF of 7.4, 8, and 8.4. At an upside up arrangement of the samples in the SBF, the formation of sufficient thick HA layers with a pillow like structure onto all SAMs were observed, which is believed to be caused by combined homogeneous and heterogeneous precipitation of HA from the SBF. These layers do not show sufficient adhesive strength. An upside down arrangement of the samples result in the formation of up to 5–10 μm thick flat HA layers with a much higher adhesive strength, which is believed to be due to formation of HA from the SBF only by heterogeneous precipitation. Also HA layers were obtained onto all studied SAMs, SH-SAM appears to favour the formation of HA resulting in a layer with a thickness of about 10 μm and an almost stoichiometric Ca/P-ratio of the layer of 1.72. All other layers exhibit much lower ratios.     

Characterization and acidic properties of Al-SBA-3 mesoporous material

SBA-3 mesostructured silica containing framework aluminum is reported here. This material was successfully synthesized using sodium aluminate via post synthesis method. The structural properties of this novel material were studied by X-ray diffraction and FTIR. The Al insertion was determined by ²⁷Al-NMR and the acidity was monitored by infrared spectroscopy of Pyridine adsorption/desorption. The ²⁷Al NMR results indicate that Al has been effectively incorporated into the framework of SBA-3 material by post-synthesis method. The bridging hydroxyl (Si₃O-Al-OH) acid sites are observed after the adsorption of basic probe molecules, such as pyridine; this fact strongly supports the presence of Bronsted acid sites. The alumination of Si-SBA-3 produces stronger Brønsted acidity than the conventional mesoporous aluminosilicates.     

利用钛精矿湿化学法合成光催化纳米粉体

利用普通的钛精矿作为起始原料,联合使用浓盐酸浸出及柠檬酸凝胶燃烧法合成一种新型光催化纳米粉体。着重研究了锌离子含量和柠檬酸历肖酸摩尔比对射米粉体的微观结构及其光催化性能的影响。利用化学分析,X射线衍射,透射电子显微镜,紫外-可见漫反射吸收光谱,紫外-可见分光光度计对合成粉体的性能进行表征。通过光催化降解甲基橙溶液来评估合成粉体的光催化活性,在高压汞灯／纳米光催化粉体／双氧水体系中,光照60min后甲基橙染料的脱色率达到95％。     

新型改性的n-HA与PLGA复合材料的制备及性能研究

采用硅烷偶联剂(KH550)和L-丙交酯LLA联合接枝处理的新方法对纳米羟基磷灰石(n–HA)进行表面改性, 然后将其与聚乳酸-羟基乙酸(PLGA)作不同比例复合(n-HA为3wt%、10wt%、20wt%及30wt%), 得到改性n-HA/PLGA复合材料(g-n-HA/PLGA)。将其与未改性n-HA及未改性n-HA/PLGA复合材料作对比检测。结果表明, 该联合处理方法是n-HA进行表面接枝改性的新型有效方法。且改性处理后的n-HA与未改性处理的n-HA相比, 能更好地在PLGA基体中分散均匀, 并能提高PLGA结晶能力和PLGA的力学性能。当改性处理后的n-HA添加量为10wt%时, 其复合材料抗弯强度和拉伸强度分别比未改性n-HA/PLGA提高14.4%和11.3%。该新型g-n-HA/PLGA复合材料有望用作骨折固定材料。     

用微波均相沉淀法合成Sc2O3纳米粉

以硫酸钪为母盐,尿素为沉淀剂,采用微波加热方式合成了水合碱式碳硫酸钪前驱体.用差式扫描量热法(DSC)、热重分析(TG)、红外光谱(IR)、X-射线衍射(XRD)分析了加热过程中前驱沉淀物的物相变化.采用高温煅烧和高能微波辐照两种方法制备了Sc2O3粉体.结果表明,将前驱沉淀物分别在1000℃煅烧3 h和在900℃微波...     

纳米Al2O3粉末的化学合成

纳米氧化铝是一种新型材料,有着广阔的应用前景.为获得性能优良的纳米粉末,许多合成方法不断涌现.主要介绍了当前氧化铝纳米粉的化学制备法,评述了常规方法中需要注意的事项,并着重叙述了目前纳米氧化铝粉末的合成新方法,最后展望了其发展方向.     

水热法制备二氧化锡纳米微粒及其表征

通过水热法,使五水四氯化锡在氨水的环境中合成纳米级的二氧化锡微粒。采用冷冻干燥法得到粉体。使用XRD对实验合成的产物进行一系列的分析,结果发现所得的二氧化锡粉体基本为四方晶系（即金红石型）。纳米二氧化锡微粒有近球形,棒状,椭球形等的形貌,其粒径范围从4nm到120nm。本实验主要研究以下几个因素对二氧化锡粉体形貌的影响：溶液的浓度、合成温度、合成时间及溶液pH值。     

中孔SAPO-34分子筛的合成与表征

以KH550和硅溶胶为硅源,用水热法合成了中孔SAPO-34分子筛,并采用XRD,氮吸附,SEM等分析方法对样品进行了分析和表征。结果表明:不同硅源配比和晶化时间对合成产物的结构和比表面有很大影响,所合成样品的总比表面积达到672m2/g,中孔SAPO-34的外比表面积可调变,在硅源配比n(KH550)∶n(Ludox)=0.6∶0.4,晶化时间为10天,总投料比为n(Al2O3)∶n(P2O5)∶n(Si)∶n(TEAOH)∶n(H2O)=1∶0.9∶0.5∶2∶60时,合成的中孔SAPO-34的外比表面积可达76m2/g。     

阴极沉淀法制备纳米Al_2O_3粉体及表征

采用阴极电化学沉淀方法制备氧化铝纳米粉体,对得到的纳米粉体进行了光吸收性能测试,并对其形成机理进行了初步的探讨。利用阴离子交换膜为隔膜的电解槽,在不添加分散剂的情况下,控制阴极的电流密度在150～500 A/m~2范围,电解一定浓度的硝酸铝溶液,在阴极室内得到Al(OH)_3沉淀,在500℃下焙烧2 h,得到不同粒度的Al_2O_3颗粒。用TEM和XRD分析表明：当阴极的电流密度为300 A/m~2时,得到的Al_2O_3粒度尺寸在30～40nm左右,晶型为γ-Al_2O_3,对波长为370 nm左右的紫外光有一定的吸收能力。     

Superparamagnetic maghemite/polyrhodanine core/shell nanoparticles: Synthesis and characterization

Maghemite nanoparticles (MNPs) with a thin layer of polyrhodanine (PRd) at the surface were synthesized via chemical oxidative polymerization of rhodanine monomer at the MNPs surface in the presence of ferric chloride as oxidant. X-ray diffraction (XRD) pattern gave direct evidence that the synthesized nanoparticles are crystalline maghemite of about 8 nm in size. Magnetization of the particles versus an applied magnetic field exhibited no hysteresis loop, indicated superparamagnetic behavior in the particles. Transmission electron microscopy (TEM) together with Fourier-transform infrared (FT-IR) spectroscopy were used to determine the morphology and the chemical structure of the magnetic core and the polymeric shell. Through the microscopy analysis the shell thickness was estimated to be about 1.5 nm, whereas through thermogravimetric analysis (TGA) it was estimated to be about 0.6 nm. Moreover inductively coupled plasma optical emission spectroscopy (ICP-OES) measurements revealed that the oxidant residue in the polymer backbone is ca. 4 wt.%.     

Calcium oxyhydroxide (CaO/Ca(OH)2) nanoparticles: Synthesis,characterization and evaluation of their capacity to degrade glyphosate-based herbicides (GBH)

Nanometric calcium oxyhydroxides (CaO/Ca(OH)₂) were synthesized by two chemical routes, controlled precipitation and polymer complex (Pechini). The ceramic powders synthesized by the Pechini method were assessed for their ability to remove organic molecules of a glyphosate-based herbicide (GBH). The nanoparticles were characterized using ultraviolet–visible (UV–Vis) absorption, infrared (IR), and Raman spectroscopies, as well as with X-ray diffraction (XRD) and scanning electron microscopy (SEM). Characterization revealed the synthesized particles to be nanometric in size (<100 nm), with an irregular morphology and a band gap of ~6.3 eV, evidencing a quantum confinement phenomenon. In testing for the removal of GBH with the CaO/Ca(OH)₂ synthesized by the Pechini method, a new product was formed by interaction with the organic molecules. The CaO/Ca(OH)₂-GBH interaction was so strong, at room temperature, that the solid completely dissolved, leaving no sediment. To determine the chemical nature of the resulting solution, aliquots were taken at the end of the test and analyzed by IR spectroscopy, revealing the existence in the system mainly of phosphate and phosphate-calcium groups, indicating that an important chemical reaction must have occurred between CaO/Ca(OH)₂ and HBG to modify the chemical structure of both compounds. The results obtained lead us to consider the synthesized CaO/Ca(OH)₂ nanoparticles as potential removers of agrochemical residues and other organic compounds that exist in water sources.     

Synthesis of Nanophase WC Powder by Displacement Reaction

ABSTRACT

Conventional thermochemical processing of nanophase WC powder involves hydrogen reduction of a tungsten precursor compound to form high surface area α-W. followed by gas phase carburization to develop WC. This two-step process inevitably leads to some coarsening of the nanophase WC powder product. Recently, we have developed a new method, called “displacement reaction processing”, in which the two steps (reduction and carburization ) are combined into a single step, leading to a much finer nanostruciure for the product WC powder. The one-step process is particularly favored when H₂ reduction of the precursor compound results in the formation of an amorphous oxygen-rich intermediate. The resulting nanophase WC has a particle size < 10 nm. In this talk, the procedures that must be followed to promote one-step WC powder processing, starting from different tungsten-based precursors, will be described, and the mechanisms discussed.     

湿化学还原法合成Co纳米粒子的研究

对水合联氨溶液直接还原法制备金属钴粉作了热力学分析并进行了实验研究,采用EDTA容量滴定分析法、X射线衍射分析(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)对钴粉的纯度、形貌、粒度及晶型进行分析表征,结果表明:在氯化钴溶液体系中,以水合联氨为还原剂,硼氢化钾为晶核引发剂,柠檬酸钠为络合剂,可制备纯度为99.5%、粒径为5～15nm的纳米金属钴粉.钴粉为混晶型产物,分别为密排六方晶型(HCP)和面心立方晶型(FCC).     

葡萄糖基炭微球的制备与结构表征

以葡萄糖为碳源制备炭微球,考察了原料浓度、反应时间和反应温度对所得炭微球形貌和产率的影响,并测定了其表面官能团的种类和数量。结果表明,葡萄糖浓度为0．5mol／L、反应温度为180℃、反应时间为7h的条件下制备了粒径300nm左右、分数性较好的炭微球。所得炭微球表面合有丰富的羟基、羰基、羧基等含氧官能团,采用联碱中和法定量测定了上述官能团的含量。     

Synthesis of Superparamagnetic Nanoparticle Ni0.50Zn0.50Fe2O4 Using Wet Chemical Method

The nanoparticles of Ni_0.50Zn_0.50Fe₂O₄ were prepared using cotton base wet chemical method. The X-ray diffraction (XRD) spectrum shows single phase cubic spinel structure, and crystallize size calculated using the Debye–Scherrer formula for 311 planes was found to be 41 nm ± 5 %. The nano range sizes of particle were confirmed using transmission electron microscope (TEM) and atomic force microscopy (AFM) images. The porosity value of the sample is promising towards sensor applications. Infrared spectroscopic results reveal two main absorption bands, indicating sample is having single phase spinel structure with two sublattices. The high DC resistivity of the sample is attributed to nano range particle sizes. The superparamagnetic (SPM) nature was confirmed from a variation of magnetic moment with applied magnetic field using VSM. The Mössbauer spectrum recorded at room temperature shows two major sextets corresponding to A- and B-site Fe ions. The relaxed sextet is associated with the atoms near the surface of the nanoparticles experiencing disordered spins. The central doublet in Mössbauer spectra of the sample indicates SPM particles. The isomer shift results show that all the Fe ions are in high state.