锰矿中锰的快速测定(H_2O_2、KMnO_4法)

(一)一般概述 H_2O_2法測定錳:是最为便捷之方法,对于锰矿及其治炼产品均能适用。本法对高含量尤称适宜,1％以下的低含量亦较ZnQ法测定准确。所存在的问题是,试样中的有机物不能被酸分解,须用碳酸钠处理。此不被酸分解的黑色残渣中锰的含量虽极微(0.01—0.4％),但足以引起误差,所以低含量试样不宜采用此法。用ZnO法测定锰,已不能适应地质工作的跃进新形势,故而我们试用H_2O_2法来测定锰,以改变我们在工作上的被动局面,经数次试验,所得结果与ZnO法非常相近。茲将我们试验结果,简述如下,供大家参考讨论。使此法更趋完善。     

NiCo_2O_4对H_2O_2在碱性溶液中电化学还原反应的催化行为(英文)

利用溶胶-凝胶法合成纳米NiCo2O4,并利用X射线衍射和透射电镜分析其结构和表面形貌.结果表明NiCo2O4具有尖晶石结构,平均粒径约为15 nm.利用电势线性扫描和恒电势法测定了其对H2O2在碱性溶液中电化学还原反应的催化性能.发现NiCo2O4对H2O2电化学还原具有高的催化活性和稳定性,在H2O2浓度低于0.6 mol.L-1时,其电化学还原反应主要通过直接还原途径进行.以NiCo2O4为阴极催化剂的Al-H2O2半燃料电池在室温下的开路电压达1.6 V;在1.0 mol.L-1 H2O2溶液中,峰值功率密度达209 mW.cm-2,此时电流密度为220mA.cm-2.     

化学镀非晶态Ni-P和Ni-B合金在H_2SO_4溶液中的电化学行为

应用极化曲线,交流阻抗等电化学测量方法分别研究了化学镀Ni-P和Ni-B合金电极在0.5mol/L硫酸溶液中的电化学行为,分析探讨了Ni,Ni-P和Ni-B合金三者在上述H2SO4溶液中其开路电位和阳极溶解特性差异的可能原因.     

ELECTRONIC ABSORPTION SPECTRA OF Cu(O_4H_4O_5)_2 ·2H_2O CRYSTAL

<正> The electronic absorption spectra of the'crystal of Cu(CtfH505) g-2H20 were measured. The experimental results were discussed quantitatively by using the ligand field theory and the radial wave function of nonfree copper(II). The electronic structure of the compound is in agreement with its crystal structure.     

电化学传感器在H_2O_2检测中的应用

将辣根过氧化酶(HRP)固定在壳聚糖(CTS)-羧基化多壁碳纳米管(C-MWNTs)复合物修饰的玻碳电极(GCE)表面,制得壳聚糖-羧基化多壁碳纳米管(HRP-CTS/C-MWNTs/GCE)电化学传感器。采用傅立叶变换红外光谱仪检测复合物包埋的HRP,发现其结构性质未发生改变;采用循环伏安法对该电极的电化学性能进行研究,结果表明:在1/15 mol·L~(-1)的PBS(pH 6.98)缓冲溶液中出现1对氧化还原峰,传感器对过氧化氢有良好的电催化还原作用。过氧化氢浓度在0.1~12 mmol·L~(-1)范围内与还原峰电流呈线性关系,相关系数(r)为0.998 6,并检测出市售医用双氧水的平均含量为2.93%。     

H_2PdCl_4和竞争吸附剂在Al_2O_3上吸附的研究

研究了H_2PdCl_4和乙酸等有机酸在Al_2O_3上的吸附行为,发现H_2PdCl_4和乙酸等六种竞争吸附剂在Al_2O_3上均呈Langmuir型等温吸附,得到了H_2PdCl_4在Al_2O_3上的吸附速度式,注意到溶液的pH值和竞争吸附剂对H_2PdCl_4的吸附动力学曲线均有影响。考察了H_2PdCl_4和竞争吸附剂共存溶液的紫外吸收光谱,对H_2PdCl_4在Al_2O_3上的浸渍过程进行了讨论。     

Al和CuCl2溶液反应机理的实验探究

铝与氯化铜反应的现象是铝丝表面析出的铜呈海绵状,同时产生了大量的氢气,为此,师生一起对铝和氯化铜溶液反应的机理进行实验探究。     

三价铬丙二酸配合物[Cr(C_3H_2O_4)(H_2O)_4][Cr(C_3H_2O_4)_2(H_2O)_2]·4H_2O的合成、晶体结构及性质研究

在三重桥氧三核铬羧酸配合物的系列研究中,采用与铬的一元羧酸配合物类似的实验条件,以丙二酸为配体合成了不同构型的配合物[Cr(C_3H_2O_4)(H_2O)_4)][Cr(C_3H_2O_4)_2(H_2O)_2]·4H_2O,通过X射线衍射测定了其单晶结构,并对-COO的配位方式作了讨论,还研究了配合物的红外光谱、拉曼光谱、紫外可见光谱、质谱、磁化率等性质,探讨了性质与结构的关系,并由此论证了二元羧酸和铬形成的双齿螯合构型化合物的稳定性.     

Bioscillation and Birhythmicity in the H_2O_2-KSCN-CuSO_4-NaOH System

Two kinds of different mechanistic oscillations can be displayed in the H_2O_2-KSCN-CuSO_4-NaOH system. One discovered by this study is the pH oscillation in a continuous flow stirred tank reactor(CSTR) resulting from the oxidation of KSCN. The other is the oscillation of H_2O_2 decomposition in both CSTR and batch reactors(reported by Orbáin in 1986). Under appropriate experimental conditions, the system exhibits a birhythmicity in a CSTR. Two different pH oscillations are reported here. The pH oscillations which accompany the decomposition of H_2O_2 exist in the batch reactor and the CSTR at a high flowrate, but the pH oscillations in a CSTR at a low flowrate originates from proton positive and negative feedback in the oxidation of KSCN. The oscillation of non-catalyzed oxidation of KSCN by hydrogen peroxide in a CSTR can be found. Also we have observed whether Cu~(2+) exists or not in the batch system, the pH increases to near neutral ultimately after pH drops twice.     

TBE EFFIGIENGIES OF THREE INITIATORS OF Fe~(2+)—H_2O_2, K_2S_2O_8, KMnO_4 AND TBE KINETIC EQUATION IN THE GRAFTING OF AGRYLAMIDE ONTO STARCH

A comparative study is made on the efficiencies of three initiators of Fe~(2+)-H_2O_2, K_2S_2O_8 and KMnO_4 in the grafting of acrylamide onto starch. Of the three initiators the best one is KMnO_4. Moreover, the kinetic equation is also studied.     

Pt/TiO_2·Nb_2O_5体系在H_2和CO气氛中的电导

近年来,Pt/TiO_2金属-半导体型催化剂在光解水制氢、水煤气变换反应和金属担体强相互作用研究中受到了人们的重视。作者曾报道过电导法检知Pt/TiO_2的晶间氢,探讨了H_2和Pt/TiO_2之间相互作用的机理,电导与红外光谱法相结合证明了Pt/TiO_2体系氢的反溢流。本工作进一步用电导法考察掺杂微量Nb_2O_5的Pt/TiO_2·Nb_2O_5体系在程序升温还原过程     

Synthesis and Crystal Structure of (C_6N_3H_(18))_2Ti_4O_4(C_2O_4)_7·4H_2O

1 INTRODUCTION The open-framework inorganic materials have been synthesized before the early 1980s[1]. Parti- cularly, metal phosphates have been investigated widely during the past few years[2, 3]. In recent years, considerable efforts have been devote…     

催化分解H_2O_2的新方法

在中等卫校的化学教材中,讲到“催化剂对反应速度的影响”时,常采用MnO_2作催化剂分解H_2O_2做演示实验:     

Ti/SiO_2催化H_2O_2氧化苯甲醇制苯甲醛反应机理的理论研究

采用密度泛函理论B3LYP方法研究了非贵金属Ti催化H2O2氧化苯甲醇为苯甲醛的反应机理.考察了6条可能的反应途径,优化得到了各个途径的过渡态和中间体结构,计算了气相和液相中的反应势垒.结果表明,无催化剂时,H2O2氧化苯甲醇的反应途径具有非常高的反应势垒,反应不能进行;以Ti/SiO2为催化剂时,标题反应在乙腈溶液中的反应势垒为123.8kJ/mol,反应可在约353K下发生.结果还表明,标题反应在极性较大的溶剂中有较高的反应势垒,而在气相或者极性较小的溶剂中的反应势垒较低.     

H_2O_2氧化N_2生成N_2O和H_2O机理的研究

采用量子化学计算方法研究了Ｈ２Ｏ２ 氧化Ｎ２ 生成Ｎ２Ｏ 和Ｈ２Ｏ 的机理．结果发现, Ｈ２Ｏ２ 氧化Ｎ２ 先通过１ 个四元环过渡态形成中间体Ｈ２Ｎ２Ｏ２ 分子,Ｈ２Ｎ２Ｏ２ 再通过一个五元环过渡态形成Ｎ２Ｏ和Ｈ２Ｏ．根据计算得到的每步反应的活化能,得知Ｈ２Ｏ２ 氧化Ｎ２ 生成中间体Ｈ２Ｎ２Ｏ２ 分子是整个反应的控制步骤．     

LiCoO_2和LiMn_2O_4在水系电解液中的赝电容研究

用溶胶-凝胶法合成了LiCoO2和LiMn2O4样品粉末。以LiCoO2和LiMn2O4电极为正极,活性炭(AC)电极为负极,分别组装成模拟非对称超级电容器AC/LiCoO2和AC/LiMn2O4,通过循环伏安、恒流充放电和电化学阻抗研究其电容性能。测试结果表明,这类非对称电容器在Li2SO4溶液中展示了较好的电容性能。在电压范围(0～1.4)V、电流密度为100mA·g-1时,AC/LiCoO2和AC/LiMn2O4电容器的初始比电容分别为45.9和44.6F·g-1。但在大电流密度下,AC/LiMn2O4具有更大的比电容和更好的循环性能。实验结果还表明,在水系电解液中,LiCoO2和LiMn2O4均是通过Li+脱嵌导致过渡元素(Co,Mn)价态变化所产生的赝电容来实现储能。     

BaB_2O_4-SrB_2O_4截面和BaB_2O_4-SrO截面的相平衡关系的研究

用X射线衍射和差热分析方法研究了在BaO-SrO-B_2O_3三元系中的BaB_2O_4-SrB_2O_4截面与BaB_2O4-SrO截面上的相平衡关系。BaB_2O_4-SrB_2O_4属共晶体系,共晶温度1076±3℃,共晶点组成为SrB_2O_4 67mol％。以BaB_2O_4或SrB_2O_4为基均可形成固溶区。在BaB_2O_4-SrO截面存在一新的化合物,其组成接近于Ba_5Sr_6B_(10)O_(26)。BaB_2O_4固溶体与Ba_4B_2O_7固溶体发生共晶反应,其共晶反应温度随SrO含量的增加从901℃上升到920℃。在富BaB_2O_4一端形成一个很宽的固溶区。在两个截面上,都由于Sr~(2+)替代了BaB_2O_4中的Ba~(2+),使高温相BaB_2O_4在常温得以稳定存在。测定了固溶体点阵常数随组成的变化。确定了常温下SrB_2O_4在BaB_2O_4中的溶解度。并从晶体结构观点讨论了固溶体点阵常数c值随组成变化而a值不变的原因。     

Synthesis and Crystal Structure of [Cu(phen)_2(SO_4)(H_2O)]·0.5C_4H_4O_4·7H_2O

1INTRODUCTION The construction of metal-organic coordination polymers based on covalent interactions[1]or supra-molecular contacts such as hydrogen-bonding and/orπ-πinteractions)[2]is now of great interest not only due to the enormous variety of intriguing structural topologies themselves,but also to their unexpected physical and chemical properties for potential prac-tical applications as functional materials.Many N-containing ligands,such as4,4?-bipyridine,2,2?-bi-pyridine and1,10-phen…     

Non-Isothermal Decomposion Kinetics of Supermolecule Compound [Eu(C_(10)H_9N_2O_4)(C_(10)H_8N_2O_4)(H_2O)_3]_2·phen·4H_2O

Europium(Ⅲ) compound with 2-oxopropionic acid salicyloyl hydrazone (C_(10)H_(10)N_2O_4,H_3L) and 1,10-phenan-throline (C_(12)H_8N_2,phen) has been prepared.A yellow prismatic crystal of the compound was obtained,and themolecule crystallized in the triclinic space group P-1.There are two 9-coordinated complex molecules in everystructure unit,where every Eu atom is coordinated by three water molecules and two tridentate C_(10)H_(10)N_2O_4 ligands,forming two stable pentacycles.The coordination polyhedron around Eu~(3+) was described as a single cap squareantiprism.In the crystal cell,there are one free 1,10-phenanthroline and four water molecules.The thermaldecomposition of the compound and its kinetics were studied by non-isothermal thermogravimetry.The Kissinger'smethod and Ozawa's method were used to calculate the activation energy value of the first-step decomposition.Thestages of the decompositions were identified by TG-DTG-DSC curve.The non-isothermal kinetic data were ana-lyzed by means of integral and differential methods.The possible reaction mechanism and the kinetic equationswere investigated by comparing the kinetic parameters.     

利用EQCM研究铅电极在硫酸和硫酸钠溶液中的反应机理

使用电化学线性扫描伏安(LSV)、循环伏安(CV)和电化学石英晶体微天平(EQCM)方法研究了硫酸和硫酸钠溶液中铅电极表面的反应过程. 伏安曲线和电极表面质量变化结果分析表明,从-1.0 V到-0.4 V正向扫描时,铅在硫酸溶液中生成两种氧化产物,在-0.87 V时生成硫酸铅,在-0.73 V时生成PbO·PbSO₄,然后PbO·PbSO₄转化成硫酸铅,而铅在硫酸钠中的氧化产物只有硫酸铅. 因此,酸性溶液是PbO·PbSO₄形成的必要条件,这进一步揭示了铅酸电池的负极放电机理,也为铅酸电池负极反应过程提供了新的研究方法.