Synthesis and Thermal Swelling of Residual Graphite Hydrosulfates Obtained Using the Na2Cr2O7-H2SO4 System

The influence exerted by the conditions of synthesis of residual graphite hydrosulfate in a system constituted by concentrated sulfuric acid and saturated aqueous solution of sodium dichromate on the properties of the final product was studied in a wide range of reagent consumptions. The swelling coefficient and the loss of the product were analyzed as functions of the intercalate content in the product.     

Influence Exerted by Cross-Linking Effect on Properties of Sorbents Produced from Aspen and Larch Bark

Russian Journal of Applied Chemistry - Method is suggested for obtaining biochar materials by treatment of a finely dispersed (≤0.1 mm) bark of aspen and(or) larch with a 40% formaldehyde...     

塞曼石墨炉AAS法直接测定硝酸银中的杂质

本文介绍了利用塞曼石墨炉原子吸收法直接测定硝酸银中的杂质锰、镍、铜、铁和铬。方法简单、快速、检出限低、回收率好。     

Synthesis and Properties of Expandable Residual Graphite Hydrosulfate Obtained in the System CrO3-H2SO4

The fundamental aspects of synthesis of expandable residual graphite hydrosulfate with the use of an oxidizing system CrO₃-H₂SO₄ at ultralow consumption of the reagents and their separate introduction into the reaction mass were studied. The dependence of the expansion ratio of the samples obtained on the content of intercalant and expansion temperature was analyzed.     

Influence Exerted by H2SiF6 on Extraction of Titanium(IV)

Extraction of titanium(IV) with octanol and tributyl phosphate from fluoride solutions that contain H₂SiF₆ or H₂SO₄ was studied.     

Synthesis and Properties of Thermally Expandable Residual Graphite Hydrosulfite Obtained in the System HNO3-H2SO4

Synthesis of bloating residual graphite hydrosulfide with the use of an oxidizing system, fuming nitric acid-concentrated sulfuric acid, was studied at ultralow expenditure of reagents and their separate introduction into the reaction mass. Important parameters of the process were revealed and their effect on the properties of the target product was determined. Ways to diminish to the maximum possible extent the adverse influence of by-products formed in the stage of graphite oxidation on the properties of the target product were found.     

Influence of Pretreatment of Expanded Graphite on Its Sorption Properties with Respect to Petroleum

Petroleum sorption on expanded graphite prepared from residual graphite hydrosulfate at 300-900°C was studied as influenced by pretreatment of the sorbent with water.     

Study of the Influence Exerted by Microscopic Additives of Fullerenes on the Absorbing Capacity of Cation-Exchange Resins for d-Elements in Aqueous Media

Russian Journal of Applied Chemistry - Introduction of fullerenes on the surface of KU-23 and KU-2-8 cation-exchange materials in amount of 0.001–0.005 wt % results in that the sorption...     

超声浸渍包覆石墨的嵌脱锂性能

锂离子电池;碳阳极;包覆;电化学性能;超声浸渍包覆石墨的嵌脱锂性能     

温度对石墨电极性能的影响

运用电化学阻抗谱(EIS)并结合循环伏安法(CV)研究了石墨电极25和60 ℃时在1 mol·L-1 LiPF6-EC(碳酸乙烯酯):DEC(碳酸二乙酯):DMC(碳酸二甲酯)电解液中, 以及60 ℃时在1 mol·L-1 LiPF6-EC:DEC:DMC+5%VC(碳酸亚乙烯酯)电解液中的首次阴极极化过程. 发现高温下(60 ℃)石墨电极在1 mol·L-1 LiPF6-EC:DEC:DMC电解液中可逆循环容量衰减的主要原因在于其表面无法形成稳定的固体电解质相界面(SEI)膜. 实验结果显示, VC添加剂能够增进高温下石墨电极表面SEI膜的稳定性, 进而改进石墨电极的循环性能.     

可膨胀石墨对室温硫化硅橡胶性能的影响

以α,ω-二羟基聚二甲基硅氧烷为基胶、纳米碳酸钙为填料、可膨胀石墨为阻燃剂,制得室温硫化硅橡胶.采用垂直燃烧、氧指数、热分析、拉伸和扫描电镜等手段研究了硅橡胶/可膨胀石墨体系的阻燃、热分解、力学性能,以及燃烧前后的微观形态.研究结果表明,可膨胀石墨是硅橡胶的良好阻燃剂,添加剂的质量分数为10%时,硅橡胶达到UL94 V...     

氟化石墨材料的改性及其电化学性能研究

本文以商用氟化石墨为原料,通过水合肼还原的方法对氟化石墨（CF_x）进行改性处理,系统研究了不同水合肼用量对材料电化学性能的影响. 采用XRD、SEM、EDS、XPS、交流阻抗（EIS）和恒流放电测试技术,对改性氟化石墨材料的物相及电化学性能进行了分析研究. 结果表明,采用改性氟化石墨材料制备的锂/氟化碳（Li/CF_x）电池的电压滞后现象得到明显改善,且不同水合肼用量对材料的电化学性能有重要影响. H-CF_x-2（CF_x：C₂H₆O：N₂H₄·H₂O 的比例为1：2：1）材料的综合性能最佳,在0.1C 倍率下,材料的克比容量达到794.5 mAh·g^-1,平台电压为2.53V,电压滞后现象的低波电压为2.37 V.     

Geographical and Geological Origin of Natural Graphite Heavily Influence the Electrical and Electrochemical Properties of Chemically Modified Graphenes

Natural graphite is an important precursor for the production of chemically modified graphenes in bulk quantities for electrochemical applications. These natural graphites have varying fundamental properties due to the different geological processes and environments at their points of origin, which are expected to affect their chemical reactivity and hence the properties of the derived graphene materials. Four different natural graphites with known geographical and geological origins were exposed to a modified Hummers oxidation method and the resulting graphite oxides were studied. The graphite oxides were shown to have different extents of oxidation and types of oxygen groups, which directly influenced their electrochemical properties. These differences were propagated further in the subsequent chemical reduction of the graphite oxides, and the reduced graphene oxides exhibited significantly different reduction efficiencies and electrical conductivities. These findings show that the choice of natural graphite of known origin is important to synthesize chemically modified graphenes with a desired set of properties.     

Influence of Residual Polyesterification Catalysts on the Curing of Polyesters

 Unsaturated polyesters are synthesized by means of polyesterification, often with catalysts like strong acids, metal oxides and metal-organic salts. Most often, the catalysts used cannot be separated from the bulk of the polyester. Also, some organic or inorganic additives – called fillers – which are used with the polyester in order to decrease cost, affect the curing of the polyester. In this work the effect of residual catalyst on the curing of unsaturated polyester is studied. Unsaturated polyesters were prepared using propylene glycol with a 10% molar excess over stoichiometry and a mixture of dicarboxylic acids, namely maleic acid (unsaturated) adipic acid (saturated) and phthalic anhydride (saturated) at a molar ratio 1:2:2. Lead dioxide, p-toluenesulfonic acid and zinc acetate were used as catalysts, at 0.1% w/w. After the polyesterification, the polymers were diluted with styrene at a proportion of 100:30 w/w. The resins were cured by using MEKP (methylethylketone peroxide) as initiator and CoNp (cobalt naphthenate) as accelerator. Catalysts affect the final color of the polyester. The kinetics of curing of the resins was studied by DSC analysis based on the exothermic peak due to the double bonds breaking to give crosslinked macromolecules. The heat released ΔH is decreased by the presence of catalyst, while activation energy, the frequency factor and the order of reaction are increased.     

稀土及杂质元素对ZA27合金晶间腐蚀的影响

To understand the influence of impurities and rare earth elements in nature on the intergranular corrosion of the zinc-aluminum alloys, taking efficient methods to retard the inter granular corrosion, the atomic cluster of α phase grain boundary including impurities (Pb, Sn, Cd), rare earth elements (La, Y) and phase grain was constructed by computer programming based on the coincidence-site lattice theory. The recursion method was used to calculate the charge transfer over the grain boundary of α phase, and discuss influence of impurities (Pb, Sn, Cd) and Rare Earth elements (La, Y) on the electrode-potential of Zn and Al. The results shows that impurity elements (Pb, Sn, Cd) can increase the charge transfer between atoms over the grain boundary, leading to the large difference of electrode-potential between Zn and Al. Therefore the eroding is speeding up, but the RE element can reduce the charge transfer between atom sover the grain boundary, and lower the difference of electrode-potential between Zn and Al. Thus RE element is of the role of restraining the inter granular corrosion of zinc-aluminum alloys.     

Influence of Light Scattering by Residual Alumina Nanoparticles on the Analysis of Surfactants Adsorption Using Spectroscopy

The adsorption of a surfactant mixture, based on an anionic surfactant, sodium dodecyl benzenesulfonate (SDBS) and a nonionic surfactant (Triton X-100, or TX100), on alumina nanoparticles was determined by solution depletion method combined with spectrometric measurement. It is shown that the light scattering, originated from the residual adsorbent alumina particles in the supernatant after centrifugation separation, interferes with the measurements of absorbance of the surfactant molecules, and therefore constitutes an error source for determination of the surfactant concentration in the supernatant by spectrometric means. The intensity of this light scattering, namely the influence of the residual alumina nanoparticles upon the surfactant adsorption, was related to the surfactant adsorption and its equilibrium concentration and varied among a batch. In this paper we report a Kalman filter method in order to eliminate the variational scattering background caused by non-separated residual alumina nanoparticles in each supernatant. This method is of interest as it is simple, easy to carry out and of high precision.     

增大层间距对天然石墨可逆储锂性能的影响研究

利用石墨嵌入化合物(GIC)制备技术处理天然石墨, 然后在其表面包覆一层软炭前驱体, 并在惰性气氛下热处理. 所得样品不但层间距保持了拉大的状态, 而且还在天然石墨内部预留了膨胀空间. 成功地找到了在保持天然石墨粒度和碳六角平面直径不显著改变情况下, 提高石墨层间距, 预留膨胀空间的石墨改性方法. 分析表明, 石墨嵌入化合物表面含有的大量含氧官能团, 在软炭前驱体包覆石墨嵌入化合物的过程中, 含氧官能团与沥青之间的反应和石墨嵌入化合物分解产生气体的溢出阻碍了层间距和预留空间的恢复. 将这种材料用于锂离子电池负极材料, 石墨的可逆储锂容量变化不大, 但是倍率放电性能和循环性能得到明显改善. 这主要是因为加大层间距和预留膨胀空间, 拓宽了锂离子扩散通道, 降低了石墨嵌锂膨胀引起的包覆层破裂.     

CaO杂质对铝型材厂工业污泥合成堇青石材料晶相结构及其含量影响

探讨原料组成对铝型材厂工业污泥合成堇青石材料的影响是非常重要的。研究目的有助于确定不同杂质在原料中允许的存在量,为选择其他原料提供可靠的依据。采用XRD法和SEM法分析各试样的晶相结构:用半定量分析方法确定各晶相的含量:用philipsX抪ertplus软件确定试样中各晶相结构参数。实验结果表明:CaO杂质含量从1.2~2.5%对合成堇青石有利:从2.5~2.8%堇青石含量开始下降:确定2.5%为CaO杂质最佳存在量,其对应的堇青石含量为91%。经plus软件确定结果:CaO杂质含量为1.2%时,其结构与单晶相同,晶胞参数变化很小:CaO含量从1.2~2.8%,其晶系由六方转变为四方结构,晶胞参数发生较大变化。镁铝尖晶石结构与晶胞参数变化较大,由单晶的立方结构转变为四方结构。     

聚合物—石墨复合材料电极

用石墨粉填充ＡＳ树脂，挤出成型制备了ＡＳ－复合导电材料电极，电极具有较好的导电性，机械强度和操作稳定性，在多种底液中具有比玻碳电极更高的氢电压值和小的残余电流。电极成功地用于Ｃｕ、Ｉｎ、Ｐｂ、Ａｂ的测定并显示较好的选择性，稳定性和再现性；并可采用浸涂法方便地进行甲基蓝修饰，得到具有稳定电化学性的修饰电极。