电泳法研究改性硅灰石的表面性质

本工作用测定水合金属氧化物等电点的方法,作为评定在硅灰石表面镁的包膜技术,为硅灰石的一物多用提供了新的途径;亦为在硅灰石表面包覆其他金属氧化物找到了一种新的方法。 本工作还研究了影响镁包覆的几种因素,结果表明,在硅灰石表面镁包膜的最佳条件为:pH=10,氢氧化镁溶胶的浓度为0.1mol·1~(-1),平衡时间为1小时,液固质量比为10以上。     

应用磺基水杨酸比色测定几种有色金属中的铁

过去,我们在测定铜合金中的铁时,是使用电解法或其他方法分离铜后,再用硫氰酸盐进行比色,此法分析过程冗长,色泽不稳定,尤其对于锡青铜试样,须先将偏锡酸沉淀用过氯酸及溴氢酸冒烟除锡,然后将溶液合并分离铜后再用比色法测定铁,步骤更为烦复。磺基水杨酸与三价铁在pH1.8—2.5时可形成稳定的褐红色Fe(SaL)~ 络合物。此时铜、铬、锌、铅等元素均无干扰。锡虽有干扰但可用乳酸隐蔽,故以磺基水杨酸法测定铜合金或锌合     

电感耦合等离子体原子发射光谱法测定铀铌混合氧化物中镉、锡和锌

铀铌混合氧化物样品0.200 0g用硝酸8mL,氢氟酸2mL进行微波消解后,经苯乙烯-二乙烯苯-磷酸三丁酯萃取柱分离铀与镉、锡、锌,采用电感耦合等离子体原子发射光谱法测定淋洗液中镉、锡和锌的含量。选择镉、锡、锌的分析谱线依次为226.502,189.989,213.856nm。3种元素的质量浓度均在一定范围内与其对应的发射强度呈线性关系,方法的检出限(3s)为0.003~0.02mg·L~(-1)。加标回收率为94.0%~101%,测定值的相对标准偏差(n=6)为3.7%~7.4%。     

硅灰石矿中硅灰石及其共生矿物的测定

硅灰石的分析已有人作过这方面的工作。在生产中我们发现,用选择性溶剂提取分离矿物的某些条件(如酸度、温度、时间等)不易控制而使分析结果的重观性欠佳,同时,在计算矿组物分含量时如果选择的元素组分不当也会带来较大的误差。本文针对辽北地区硅灰石矿中硅灰石的共生矿物比较简单的特点,用稀盐酸一次提取硅灰石及共生矿物,用准确度高的分析方法测定MgO、Fe_2O_3、Al_2 O_3等组分,通过测定灼烧减量(LOS)来测定碳酸盐总量,经计算     

ZnFe2O4薄膜/锡掺杂玻璃复合光波导敏感元件的研究

采用浸渍-提拉法,将铁酸锌溶胶固定在锡掺杂玻璃光波导元件表面,通过不同的热处理温度(400℃,500℃,600℃)得到ZnFe2O4薄膜/锡掺杂玻璃复合光波导敏感元件,且对低浓度的苯乙烯蒸汽进行检测。在500℃热处理的传感元件对苯乙烯(相同浓度的挥发性气体中)的响应较大,并在体积比2.0×10-10~2.0×10-6范围内有较好的响应。响应时间和恢复时间分别为17s和60s。     

隐蔽剂在螯合滴定中的应用(Ⅺ)——苦杏仁酸可作为锡(Ⅳ)的新隐蔽剂

本文提出苦杏仁酸为锡(Ⅳ)的新隐蔽剂,在pH2至5.5均能隐蔽锡,其隐蔽能力以在pH3.0至3.5最强,1克的苦杏仁酸足以隐蔽35毫克的锡。建立了EDTA-苦杏仁酸隐蔽法间接滴定锡,锆、钍、铋、铁(Ⅲ)、镓、铈、镧、汞铅、镍、钴、锌、镉、钙、镁、少量锰和铝(用丙二酸隐蔽)、钛(加入过氧化氢)、锑(Ⅲ)(用酒石酸隐蔽)等不干扰。本法选择性很高,溶样后即可准确测定锡合金或锡矿中的锡。     

标准加入-原子荧光光谱法测定罐头中的痕量锡

用微波消解处理样品,采用标准加入-原子荧光光谱法测定罐头中的锡.通过实验探讨了样品预处理条件、仪器条件、微波消解程序、还原剂浓度等对锡测定的影响.锡浓度(X)在1～100 μg/L范围内与荧光强度(Y)呈线性关系,线性方程为Y=50.15X+12.13,相关系数r=0.9995.用该法对水果和蔬菜罐头样品进行了测定,并...     

锡青铜中锡锌铅的连续滴定

锡青铜中锡、锌、铅的测定,目前大都采用一份试液分别测定的方法。本文采用同一份称样,用络合滴定法直接连续测定锡、锌、铅三个元素。试样以盐酸、过氧化氢溶解,用硫脲掩蔽铜,抗坏血酸掩蔽铁,加入过量EDTA标准溶液,将锡、锌、铅全部定量络合。以六次甲基四胺调至pH5.5,以二甲酚橙、溴甲酚绿作指示剂,用硝酸铅标准溶液滴定过量EDTA。而后,加氟化铵使Sn-EDTA中释放出等摩尔的EDTA,用硝酸铅标准溶液滴定,其量为锡。然后,加亚铁氰化     

微结构与表面修饰对二氧化硅多孔薄膜疏水性能的影响

通过引入聚乙二醇(PEG)改性传统二氧化硅(SiO2)溶胶,得到了粒径分布较宽且粒径可控的溶胶。比较了六甲基二硅氮烷(HMDS)溶胶内修饰和薄膜表面修饰以及溶胶粒径对SiO2薄膜疏水性能的影响。采用动态光散射粒度仪定量测试了二氧化硅溶胶老化过程中粒度的变化,用原子力显微镜、接触角测试仪、红外光谱仪、紫外-可见-近红外分光光度计分别对薄膜的表面形貌、表观静态接触角、薄膜成分及透光率等进行了测量。结果表明:PEG的添加可有效增大溶胶粒度从而增大薄膜的粗糙度,提高薄膜的疏水性。表面修饰效果受修饰方式和SiO2粒径影响,粒径较小时有利于溶胶内修饰,粒径较大时有利于对薄膜修饰。经过表面修饰剂(HMDS)的气氛处理得到了接触角为152°的超疏水薄膜,而且相比溶胶内修饰可以减小薄膜透光率的损失。     

偏锡酸锌纳米微粒的水热法制备及其对甲基橙降解的光催化性能

以醋酸锌和氯化锡为原料,以聚甲基丙烯酸钠(PMA)为表面活性剂,利用水热法合成了偏锡酸锌(ZnSnO3)纳米微粒;采用X射线衍射仪、傅立叶变换红外光谱仪、扫描电镜等分析了ZnSnO3纳米微粒的晶相、表面组成、形貌;并测定了ZnSnO3纳米微粒对甲基橙溶液的光催化降解性能.结果表明,所得ZnSnO3纳米微粒粒径约为20nm,表面存在羧基;其对pH=2的甲基橙溶液的光催化降解效果较好,甲基橙的初始浓度越低,降解效果越明显;随着催化剂用量的增加,降解效率逐渐增大.此外,循环催化试验结果表明ZnSnO3纳米微粒具有较好的催化稳定性.     

树脂基硅灰石复合材料的研究进展

我国是硅灰石资源大国，硅灰石在各种树脂中有广泛的应用。影响树脂基硅灰石复合材料性能的因素有很多，本文从聚合物基体和硅灰石填料两个方面对国内外部分树脂基硅灰石复合材料的研究成果进行了综述，探讨了硅灰石增强增韧聚烯烃的方法和机理，并追踪了国内外的最新研究动态。     

锆螯合物交联丙烯酸酯共聚物无皂水溶胶的研究Ⅱ锆螯合物与丙烯酸酯三元共聚物无皂水溶胶的交联反应

研究了三元丙炮酸酯共聚物（MMA／BA／AA）无皂水溶液中加入三乙醇胺锆螯合物对水溶胶及涂膜性能的影响，在水溶胶中，螯合物增加了共聚物的亲水性，改变了水溶胶的流变性、稳定性、表面张力、螯合物也提高了共聚物涂膜的耐水性，X光电子能谱（XPS）研究表明，在固化成膜过程中螯合物与共聚物发生交联反应，用IR、^1HNMR、DSC、TGA和UV等方法对其交联机理作了初步探讨。     

纳米复合钛白的研制

以硅灰石为核心,采用化学沉淀法在其表面均匀包覆一层纳米TiO₂,形成了硅灰石复合钛白。包覆过程中硅灰石的预处理是关键一步。经XRD,IR,SEM,TEM和XPS对复合钛白进行表征,结果表明,包覆完全的硅灰石复合钛白性能与钛白粉相当。     

Comparative study of the properties of silver hydrosols prepared by “citrate” and “citrate-sulfate” procedures

Comparative study of the properties of silver hydrosols prepared with the use of two classical procedures (“citrate” and “citrate-sulfate”) is performed. The possibility of using these procedures for the synthesis of stable monodisperse silver hydrosols with particle diameters of 20 nm and more is studied. The effect of the main parameters of synthesis (the ratio of initial components, the rate of their mixing, etc) on the hydrosol characteristics is investigated. It is revealed that, in the case of “citrate” synthesis, it is quite impossible to realize conditions ensuring the reproducible preparation of colloidal solutions with particles having sufficiently uniform size and shape. The procedure for the one-stage preparation of “citrate-sulfate” hydrosol (without multiple precipitation-redispersion of nanoparticles) is elaborated and it is shown that the thus prepared hydrosol is greatly superior in both the optical characteristics and the morphological uniformity of particles to the citrate sol. An increase in synthesis temperature to 100°C leads to a substantial enhancement of the stability of colloidal solution. The possibility of using “citrate-sulfate” hydrosol for the design of two-dimensional ensembles of silver nanoparticles on the quartz and silicon surfaces modified with poly(2-vinylpyridine) is demonstrated. It is shown that such ensembles possess optical properties that allow to use them in designing “two-dimensional” polymer-metal nanocomposites potentially suitable for using as active media in devices working on the principle of surface plasmon resonance.     

具有双亲特性的水相哑铃型SiO2纳米粒子的制备

以纳米SiO2水溶胶为原料,3?氨丙基三乙氧基硅烷(APTES)和3?氯丙基三乙氧基硅烷(CPTES)为改性剂,在水基环境下分别对SiO2纳米粒子进行改性,得到了具有亲水特性的APTES改性SiO2粒子和具有亲油特性的CPTES改性SiO2粒子水溶胶。2种粒子按不同比例混合,利用接枝在SiO2粒子表面氨基和氯丙基的取代反应,使得2种具有亲水/亲油特性的改性SiO2纳米粒子偶联,制备了粒径为40~50 nm的哑铃型SiO2纳米粒子。并通过透射电镜(TEM)、傅里叶变换红外光谱(FT?IR)、X射线光电子能谱(XPS)以及动态光散射(DLS)等方法对其进行了系统表征。结果表明,2种粒子成功偶联形成了具有哑铃型结构的水相SiO2纳米粒子,该粒子两面具有不同的亲水性,粒径近似等于APTES改性SiO2粒子和CPTES改性SiO2粒子的粒径之和。     

一类新的非线性光学材料的研究——Fe2O3氧化物超微粒溶胶

80年代以来,超微粒材料的光学非线性引起了广泛的注意,其大的三阶光学非线性系数和快的响应,可能在光电子学中获得应用。这种非线性,是由具有量子尺寸效应(quantum size effect)的超微粒中的载流子限域运动(carrier confinement)和载流子间相互作用引起的,局域场效应(local field effect)可增强这一非线性过程^[1]。     

In situ UV–visible and IR absorption study of the aggregation of silver colloidal particles via chemisorption of octadecanethiol

Aggregation of silver colloidal particles in the hydrosol via chemisorption of octadecanethiol (ODT) molecules was investigated based on in situ UV–visible transmission and infrared attenuated total reflection (ATR) measurements. As‐prepared silver hydrosol exhibits a single absorption peak at 395 nm because of the plasma resonance of the metal particles. Upon addition of ODT‐dissolved ethanol to the hydrosol, the resonance band red‐shifts and broadens, the detailed features of which depend on the ODT concentration and elapsed time. Both the red‐shift and the broadening are attributed to particle aggregation in the solution via ODT chemisorption. Aggregation on a germanium prism surface by the addition of ODT‐dissolved ethanol to the hydrosol was investigated using infrared ATR spectroscopy. At moderate ODT concentrations, intense aggregation via ODT chemisorption occurs strongly on the prism surface, allowing observation of ODT absorption bands. Angle‐dependent infrared ATR measurements for the ethanol and ODT molecules at the prism/solution interface clearly show that aggregation on the prism surface proceeds via the exclusion of ethanol. Copyright © 2004 John Wiley & Sons, Ltd.     

The Effect of Acrylic Acid on Tensile and Morphology Properties of Wollastonite Filled High Density Polyethylene/Natural Rubber Composites

Inorganic filler manufactured for incorporation into thermoplastic elastomers usually are surface treated with organic reagents in order to improve the interfacial adhesion between filler and the matrix. In the present paper, the effects of acrylic acid (AA) on tensile and morphology properties of wollastonite (WS) filled high density polyethylene (HDPE)/Natural Rubber (NR) composites were studied. The untreated and treated HDPE/NR/WS composites were melt-blending at 180 °C with rotor speed of 50 rpm for 10 minutes. The composites were tensile-tested according to ASTM D638 and the etched surfaces were observed using scanning electron microscope (SEM). Tensile strength and elongation at break of the compositesdecreased upon the addition of wollastonite, but Young's modulus improves. The results of this study showed that the treated composites are found to have better tensile properties than the untreated composites. The morphology of treated composite showed better interfacial interaction between HDPE/NR and wollastonite.     

Metal Nanoparticles on Polymer Surfaces: 2. Catalytic Activity of Platinum Nanoparticle Ensembles on Polystyrene

Catalytic properties of platinum nanoparticles deposited onto polystyrene surface from their hydrosol stabilized with sodium polyacrylate are studied. It is shown that, during the adsorption on polymer substrate, metal nanoparticles form rather densely packed ordered monolayer ensembles with high catalytic activity in the model reaction of hydrogen reduction of methyl viologen. This allows one to measure the reaction rate with standard spectrometric method using polymer film with the surface area of 1 cm² or less as a catalyst support.     

Effect of Low-Temperature Treatment of Silver Hydrosol on Its Absorption Spectra

Absorption spectra of a stable silver hydrosol before and after low-temperature treatment were recorded and analyzed. An increased duration of this treatment leads to linear decrease in volume concentration of Ag particles having an absorption maximum _max = 412 nm and to the formation of a new fraction of larger particles. It was shown on the basis of calculation of spectra by the Mie theory and the theory of plasmon resonance absorption that the low-temperature treatment of hydrosol does not change the electron density of metal particles and the number of surface defects. The effect of low-temperature treatment is independent of sol concentration. The particle aggregation under low-temperature treatment conditions is favored by the preliminary adsorption of p-phenylenediamine derivative.