化学沉淀法合成纳米SiO2

本实验以硅酸钠和氯化铵为原料,以乙孵水溶液为溶剂,用沉淀法制备SiO2超细粉体,并用XRD、TEM和SEM对粉体的基本性能进行表征：结果表明：该法制得的SiO2粉体近似呈球形,平均粒径为40nm。     

化学沉淀法制备纳米乳酸钙

以乳酸与氢氧化钙为原料,采用化学沉淀法制备了纳米乳酸钙,研究了影响所制备乳酸钙粒径的因素,采用粒度分析仪、分光光度计、XRD及TEM对粉体进行表征。研究结果表明：采用化学沉淀法制备纳米乳酸钙需在乳酸钙溶液接近饱和时,过滤除去未反应的氢氧化钙,抑制目标产物二次成核;向滤液中加入适量的乙醇,促进成核,抑制晶体的生长,并提高纳米粉体的分散性;采用化学沉淀法适宜的工艺条件制备乳酸钙粉体平均粒径分别可达52．3nm,粒度分布窄,乳酸钙纯度达到99％以上,质量符合食品级乳酸钙的国家标准（GB6226-86中砷及重金属含量）要求。     

化学沉淀法制备纳米二氧化硅

以水玻璃和盐酸为原料,采用化学沉淀法制备纳米SiO2。工艺条件为：温度40-50℃,pH值5—6,干燥温度110℃,焙烧温度500℃,制得的二氧化硅粒径在50-60nm,比表面积大,分散性好,达到了工业生产的标准。     

沉淀法制备纳米级粒子的研究——化学原理及影响因素

本文详细介绍了沉淀法制备纳米级粒子的化学原理，重点讨论了反应物浓度，反应温度，表面活性剂，ｐＨ值及反应时间等诸因素对粒子大小，形状的影响。     

反向化学沉淀法制备纳米ZrO_2超细粉体

以ZrOCl2.8H2O和NH3.H2O为原料,采用反向化学沉淀、有机物共沸蒸馏法制备超细ZrO2,用XRD、TEM、BET等技术研究粉体的组合结构、晶粒大小、比表面和孔径分布情况。结果表明,纳米ZrO2超细粉体由单斜和四方晶相组成,透射电镜分析提示产物粒径在10~20 nm;样品经400℃焙烧4 h后粉体的比表面积为115.64 m2/g,平均孔径为6.375 nm,总孔容为0.369 mL/g。该粉体具有高比表面性,可用于工业催化剂的载体。     

化学沉淀法制备纳米二氧化硅

采用硅酸钠为硅源,氯化铵为沉淀剂制备纳米二氧化硅.研究了硅酸钠的浓度、乙醇与水的体积比以及pH值对纳米二氧化硅粉末比表面积的影响,并用红外、X射线衍射和透射电镜对二氧化硅粉末进行了表征.研究结果表明在硅酸钠浓度为0.4 mol/L,乙醇与水体积比为1∶ 8,pH值为8.5时可制备出粒径为5～8 nm分散性好的无定形态纳米二氧化硅.     

无机盐为原料化学沉淀法制备纳米SnO2材料的研究进展

对近年来有关以无机盐为原料用化学沉淀法制备纳米SnO2材料的研究作综述,分析讨论了在制备纳米SnO2过程中,各主要因素对纳米SnO2材料制备的影响,简要地介绍了纳米SnO2材料的一些性能、用途。讨论了化学沉淀法制备纳米SnO2过程中存在的主要问题、发展前景及今后的研究方向。     

各向异性Janus纳米粒子的制备表征化学实验设计

设计了一个“一种各向异性的Janus纳米粒子的制备及表征”的综合化学实验。本实验设计将具有各向异性的Janus纳米粒子的合成、分离提纯、结构表征和应用功能融为一体,在实验过程中,引导学生探索Janus纳米粒子的合成机理,掌握分析仪器在材料结构和性能表征过程中的应用,激发学生的科研兴趣,培养学生基础实验操作技能以及使用现代仪器对产物进行结构分析的专业科研能力。     

沉淀法制备α-Fe2O3纳米晶

研究了以FeCl3·6H2O和FeSO4·7H2O为源物质,用均相沉淀法和直接沉淀法制备α-Fe2O3纳米晶粉体,利用TEM、XRD、BET、H2-TPR手段对样品进行了表征.实验结果表明,均相沉淀法所制得α-Fe2O3粉体晶粒尺寸为20nm左右,比表面积大,反应性能好;直接沉淀法所制得粉体晶粒尺寸为80nm左右,比表面积小,反应性能相对差.     

沉淀法制备纳米氧化铟粉末

为了开发适合工业化大规模生产超细且分散性好的In<,2>O<,3>粉体的方法,作者以金属铟、盐酸、氨水为原料,对化学沉淀法制备纳米氧化铟粉末的过程进行了研究.通过严格控制实验条件制备出了单相、分散性好、晶粒尺寸约为30nm,粒度分布范围窄的立方晶系纳米In<,2>O<,3>球形粉末.     

T型微混合器合成Cu2O纳米颗粒

采用T型微混合器通过沉淀法,以氯化铜为铜源,氢氧化钠为沉淀剂,抗坏血酸为还原剂制备出了立方体氧化亚铜纳米颗粒。考察了进料流量、氢氧化钠浓度、抗坏血酸浓度和温度对产物氧化亚铜的形貌、粒度及其分布的影响。采用X射线衍射、场发射扫描电子显微镜和紫外可见分光光度计对其进行表征。结果表明,随着进料流量的增大、氢氧化钠浓度的减小、抗坏血酸浓度的增加和温度的提高,所制备的氧化亚铜颗粒的平均粒径减小、粒度分布变窄。     

双微乳液法制备纳米硫酸钡颗粒

在水溶液/TritonX-100/正己醇/环己烷组成的反相微乳液中,以氯化钡和硫酸钠为原料,通过沉淀反应,制备出类球形BaSO₄纳米颗粒,并通过XRD、SEM、TEM、FTIR对其进行表征。考察了三种反应方式、水/TritonX-100摩尔比（R）、反应物浓度以及助表面活性剂/表面活性剂摩尔比（P）对纳米BaSO₄颗粒大小和形貌的影响。同时考察了R对微乳液液滴大小和粒径分布的影响,并通过动态光散射技术（DLS）对微乳液液滴进行测定。实验结果表明：室温条件下,采用双微乳液法,R=17.97,P在2.11～4.22之间是纳米BaSO₄颗粒合成的最佳反应条件,反应物浓度对BaSO₄颗粒的大小和形貌几乎没有影响。在该反应条件下,合成出的类球形BaSO₄粒径为18～22 nm,产率可达87.5%。     

Synthesis of molybdenum carbide nanoparticles using pulsed wire discharge in mixed atmosphere of kerosene and argon

Pulsed wire discharge was used to prepare nanoparticles of molybdenum and its carbides from Mo wires in a gas mixture of argon and kerosene at pressures of 100, 50, and 25 kPa. The different pressures affected the carburization process and particle formation. The most effective pressure was 25 kPa, where the volume fraction of MoC was identified by Rietveld refinement of X-ray diffraction data to be 98.4%. The particle size distribution was also obtained from transmission electron microscopy measurements, and the smallest geometric mean diameter was determined tobe 24.3 nm for the sample prepared at 25 kPa.     

Size-controlled green synthesis of silver nanoparticles assisted by L-cysteine

A green and size-controlled synthesis of silver nanoparticles (Ag NPs) in aqueous solution with the assistance of L-cysteine is presented. The size of Ag NPs decreases with the increase of L-cysteine concentration, and thus can be controlled by adjusting L-cysteine concentration. TEM analysis shows that Ag NPs with an average size of 3 nm can be produced in the presence of 1.0 mmol/L L-cysteine, about one sixth of the size of Ag NPs obtained in the absence of L-cysteine (17 nm). The as-synthesized silver colloidal solution is stable and can be stored at room temperature for at least two months without any precipitation. This L-cysteine assisted method is simple, feasible and efficient, and would facilitate the production and application of Ag NPs.     

化学沉淀法处理含铝有机酸废水

针对某生产过程中产生的大量难处理的有机酸铝配合物,利用化学沉淀的方法,以丝钠铝石为产物,在保留水中有机酸根的前提条件下,把废水中的铝离子以沉淀的形式分离出来。实验结果表明,当废水初始pH为11,反应温度为60℃,n(NaHCO3)∶n(Al)=10∶1,水浴时间为4 h时,废水中铝的去除率可以达到96%以上。该方法不仅可以很好的降低水中铝离子浓度,同时可以将白色沉淀焙烧,以氧化铝的形式回收水中的铝离子,同时废水中的有机酸根会保留在废水中,残留率为50%左右,实现资源循环利用。     

Organic nanoparticles recovery in supercritical antisolvent precipitation

One of the major problems in dry nanoparticles production and handling is their recovery. Indeed, they tend to disperse in all the precipitation chamber and, due to their dimensions, are very difficult to collect.Supercritical antisolvent precipitation (SAS) was frequently used to produce nanoparticles at very mild conditions of pressure and temperature, but the issues of sedimentation mechanisms and nanoparticles recovery as single units, have not been evaluated yet.In this work, SAS nanoparticles were produced for samarium acetate, rifampicin, astemizole, amoxicillin trihydrate, tetracycline hydrochloride, clemastine, cellulose acetate and disperse red 60; the powders were collected as aggregates, due to the specific sedimentation mechanism that characterizes the process. SAS produced nanoparticles of the previously listed materials were precipitated from different organic solvents. Then, they were post-processed by ultrafiltration, ultracentrifugation and ultrasound based techniques, demonstrating that they can be easily separated in single nano-units. Nanoparticles showed mean diameters in the range 50-150 nm.     

化学沉淀法处理磷化废水

作者提出了用化学沉淀法处理磷化废水的工艺流程和技术参数.经过半年的现场调试,废水中PO43-的去除率达到99%以上,出水水质达到国家排放标准.     

Synthesis of gold nanoparticles in hyperbranched polyol dispersions

In this study, a series of different generation hyperbranched poly(amine‐ester) with hydroxyl as terminal group were synthesized and used as protectants to synthesize gold nanoparticles with a facile and highly reproducible method. The effect of hyperbranched poly(amine‐ester) generation on size and their distribution of gold nanopartciels were discussed. The results of ultraviolet visible absorption spectroscopy, Transmission electron microscopy and scanning electron microscopy showed that the mean diameter were 24.3 ± 2.6 nm, 18.2 ± 2.1 nm, and 13.6 ± 1.5 nm corresponding to the different generation hyperbranched poly(amine‐ester), and the synthesized gold nanoparticles were almost monodisperse with a narrow size distribution. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis of CaCO3 nanoparticles by controlled precipitation of saturated carbonate and calcium nitrate aqueous solutions

Calcium carbonate nanoparticles (CCNP) were synthesised by precipitation from saturated sodium carbonate and calcium nitrate aqueous solutions. The effect of agitation rate, mixing time, calcium/carbonate ions concentration and temperature on particle size and morphology were investigated. Particles were characterised using X‐ray diffraction (XRD), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). Increasing the mixing time from 30 to 180 min resulted in a decrease in particles size. Mixing rate variation between 300 and 14 000 rpm decreased the particle size. Temperature increase favoured a significant growth in particle size and in the formation of aragonite beginning from 80°C. Calcium and carbonate ion concentrations are key parameters controlling the CCNP particle size. Calcite is the main polymorph obtained as revealed by XRD analysis. © 2011 Canadian Society for Chemical Engineering