Surface Modification of a Magnetic SiO2 Support and Immobilization of a Nano-TiO2 Photocatalyst on It

This study presented an effective method to modify the surface chemical reactivity of a SiO₂/Fe₃O₄ support. The unmodified SiO₂/Fe₃O₄ support was prepared by the hydrolysis and condensation of tetraethoxysilane on the surface of hydrophilic Fe₃O₄ nanoparticles. These were then modified by a heat treatment in an ethanol/water solution under reflux. The resulting samples were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and transmission/scanning electron microscopy. The immobilization of a TiO₂ nanocatalyst on both unmodified and modified supports was performed to investigate the effects of the modification of the magnetic silica support on the loading of a TiO₂ nanocatalyst and the photocatalytic activity. The loading of TiO₂ and the photocatalytic activity were both improved.     

复合软模板法可控制备红毛丹状AlOOH/Al2O3纳米材料

以Al(NO₃)₃为铝源,尿素为均相沉淀剂, 在聚乙二醇400(PEG4000)-DL-天冬氨酸形成的复合软模板体系中, 通过简单的常压回流方式成功合成出形貌和尺寸较为均一的红毛丹状γ-AlOOH纳米结构, 继而考察了反应物和添加剂用量对前驱体形貌和尺寸的影响, 并对γ-AlOOH纳米结构可能的形成机理进行了探讨. 实验结果表明, 所合成的红毛丹状γ-AlOOH具有球中球的核壳结构, 统计得内球直径约为400 nm, 外壳外径约为600 nm, 密集状态的壳层厚度约为15 nm, 毛刺状凸出物长度可达60 nm以上. 前驱体样品经600℃煅烧5 h后即转变为具有良好形貌继承性的γ-Al₂O₃, Brunauer-Emmett-Teller (BET) N₂-吸附实验表明其比表面积高达299.97 m²·g^-1.     

The noble effect of aging on the thermal conductivity of modified CNTs-ethylene glycol nanofluids

In order to improve the heat transfer process by using nanofluids, different nanoparticles and base fluids have been studied. In this work, stability and effect of aging and temperature on the thermal conductivity of CNTs-ethylene glycol (EG) nanofluids were investigated. Chemical functionalisation was used to oxidise the surface of CNTs. The functionalised CNTs were used to prepare the nanofluids by a two-step method. The stability of nanofluids was measured by UV-vis spectroscopy and the results showed that the nanofluids had a good stability over several days. Immediately after nanofluid preparation not too much increase was observed for thermal conductivity but the nanofluid aging had a great influence on the improvement of the thermal conductivity, as after 65 days, about 50% increase was observed. The increase has been attributed to forming an ordered nanolayer of EG molecules around the CNTs. Also no significant temperature dependence of thermal conductivity was observed up to 50°C possibly due to the lack of temperature dependence of CNTs Brownian motions.     

常压回流掺钴钙锰矿锂离子电池正极材料

常压回流法制备掺杂钴离子的钙锰矿,X-射线衍射(XRD)、热重(TG)、化学分析等测试表明:钙锰矿均为单一相,组成为MgxCoyMnOz·nH2O,其中0.18≤x≤0.22、0≤y≤0.24、2.10≤z≤2.53、0.35≤n≤0.73.以掺钴钙锰矿作锂离子二次电池正极材料,组成为Tod-Co10%(10%Co的Mg0.18Co0.12MnO2.19·0.45H2O)电极放电性能最佳,其首次放电比容量为219mAh/g,100次循环充放电仍有102mAh/g.对比之下,未掺钴的Tod-Co0%电极(钙锰矿)首次放电比容量为211mAh/g,30次循环后为37mAh/g.     

Electrical conductivity enhancement of polyaniline by refluxing

The room temperature electrical conductivity of polyaniline (PANI) was found to increase remarkably after it was heated in tetrahydrofuran (THF) with refluxing for a certain period and then doped with methanesulfonic acid (MSA). The enhanced electrical conductivity of PANI was attributed to a partially cross‐linked network generated via the formation of new chemical bonds between adjacent PANI chain segments during thermal treating, which may shorten the inter‐chain distance and facilitate inter‐chain transition of charge carriers in doped PANI. During the refluxing, the moderate dissolving power for PANI as well as a much lower boiling point of THF were considered to have a unique effect on the formation of such partially cross‐linked network in PANI. As a comparison, PANI treated in poor solvents like methanol (or ethanol) and PANI treated in dimethyl formamide (DMF), which is a better solvent than THF but has higher boiling point, did not show an obviously increased electrical conductivity. Study on X‐ray diffraction (XRD) analysis of PANI after refluxing showed that crystallinity decreased gradually with the increase of cross‐linking degree, but the inter‐chain cross‐linking probably occurred first in crystalline region and then in the amorphous region. Electrical conductivity of PANI decreased after it was refluxed with THF for an extended period due to the decreased crystallinity and doping in PANI. Copyright © 2010 John Wiley & Sons, Ltd.     

川芎中内酯类化学成分的提取与溶剂萃取分离方法研究

以川芎中4种主要内酯的总量为指标,系统地研究了乙醇浓度、乙醇用量、回流次数、回流温度、萃取溶剂种类和用量等因素对水浴回流法提取川芎内酯的影响,确定了川芎内酯的最佳提取工艺:10倍量体积分数75%的乙醇,60℃水浴中回流提取两次,乙酸乙酯作萃取溶剂,萃取溶剂的最佳用量为11mL/g药材。经反相高效液相色谱法测定,溶剂萃取后的提取物中4种主要内酯(洋川芎内酯-H、洋川芎内酯-I、瑟丹酸内酯和蒿本内酯)的总量为24%~30%。     

单分散球状纳米金颗粒的合成*

综述了近年来单分散球状金纳米颗粒的合成研究进展。分析了球状单分散金纳米颗粒的应用前景,介绍了单分散球状金纳米颗粒的主要合成方法如种子生长、回流熟化、尺寸选择沉淀分级以及电泳法等,评述了各种方法的优缺点。最后提出了单分散球状金纳米颗粒合成的一些问题,并展望了单分散球状金纳米颗粒的研究和发展方向。     

回流法合成硫化锑纳米棒及其光催化性能研究

以三氯化锑(SbCl₃)、硫粉(S)和硼氢化钠(NaBH₄)为原料, 1,2-丙二醇(C₃H₈O₂)作溶剂, 用回流法成功合成了Sb₂S₃纳米棒. 用XRD, EDS, SEM, TEM, HRTEM, SAED以及UV-Vis等手段对所制备产品的晶型、成分、形貌和光学特性进行了表征|以太阳光为光源、亚甲基蓝为目标降解物评价了Sb₂S₃纳米棒的光催化活性. 结果表明, 经186 ℃回流15 h可得到直径约为78～180 nm、长度达2～5 μm的正交晶系的Sb₂S₃单晶纳米棒. 经计算, 其晶胞参数a＝1.124 nm, b＝1.138 nm, c＝0.384 nm. UV-Vis分析表明, Sb₂S₃纳米棒为半导体材料, 其带隙能量为1.52 eV. 光催化性能测试表明, 所制备的Sb₂S₃纳米棒在太阳光下对亚甲基蓝具有较高的光催化降解率, 经20 min降解, 亚甲基蓝的降解率达84.31%, 表现出明显的可见光活性. 加入的PVP对控制Sb₂S₃的形貌有重要的作用. 另外, 还讨论了Sb₂S₃ 纳米棒可能的形成机理.     

苯并[d]咪唑基Ni(Ⅱ)配合物的合成、晶体结构与荧光性质研究

以3-(4-羧苯基)-7-甲基-2-丙基-3H-苯并[d]咪唑-5-羧酸和六水合氯化镍为原料,采用混合溶剂加热回流方法合成出了一例具有三维超分子结构的镍配合物,并通过X射线单晶衍射、元素分析、红外光谱、紫外-可见光光谱和荧光光谱表征方法对其进行了结构解析和性质表征。X-射线单晶衍射结果表明,配合物属于三斜晶系,P1空间群;其晶胞参数为a=0.778 5(16) nm,b=1.126 6(2) nm,c=1.175 6(2) nm, α=113.63(3)°,β=93.24(3)°,γ=101.00(3)°,V=0.917 1(3) nm³。标题配合物为单核配合物,由4个配体阴离子连接中心Ni(II)离子形成了一维环形链,并进一步通过氢键和π-π堆积作用形成了三维超分子结构。荧光光谱分析结果表明配体和标题配合物均具有良好的荧光性质,且配合物的荧光性质优于配体。     

Quantitative preparation of allyl telechelic polyisobutylene under reflux conditions

Allyl telechelic polyisobutylene (allyl‐PIB‐allyl) is of great commercial and scientific interest produced by living polymerization of isobutylene followed by functionalization (allylation with allyltrimethylsilane) under external cooling, typically to ?78 °C. Cooling is cumbersome and costly, and temperature control is far from ideal. Herein we describe the quantitative preparation of allyl‐PIB‐allyl under ideal internal temperature control at ～?40 °C using refluxing propane/methyl chloride mixtures. The exact composition of the nonpolar/polar solvents and polymerization time crucially affect product quality. Well‐defined allyl‐PIB‐allyl is obtained using 60/40 (v/v) refluxing propane/methyl chloride and terminating not more than 5 min after monomer depletion. In pure refluxing propane or methyl chloride, or at longer reaction times, byproducts form that compromise product quality. A mechanism is presented to explain the observations. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 1784–1789