The Applicability of Debye-Hückel Model in NaAl(OH)_4-NaOH-H_2O System

1 INTRODUCTION NaAl(OH)4-NaOH-H2O system plays a paramount role in the industry of alumina production, and the calculation of its activity coefficients can not only aid to perfect the theory of alumina production, but also accelerate the research and the development of new technology for reducing the production cost and energy consumption. However, the solution in alumina industry has high concentration with extremely complex structure, and the properties of the solution are easily affe…     

Leaching Gold Using Oxidation Products of Elemental Sulfur in Ca(OH)2 Solution Under Oxygen Pressure

A gold leaching process by using in situ oxidation products of added elemental sulfur in Ca(OH)2 solution was investigated. A gold concentrate containing 45 g/t Au was tested and 85%~87% of gold were leached. The leached gold depends mainly on the initial molar ratio of elemental sulfur to the hydroxyl ion, the consumption of oxygen and the reaction temperature. Adding some surfactants, such as lignosulfonic calcium, at lower concentration increased the leached Au but at higher concentration decreased it. Both of thermodynamic analysis and experimental results show that thiosulfate is the major complexing agent for gold in the process.     

Al3(SO4)2(OH)5H2O与α-Al2O3晶须的制备及其生长机制

采用液相沉淀及烧结方法制备了Al3(SO4)2(OH)5H2O与α-Al2O3晶须,样品采用XRD、SEM及G-DTA等对样品物相、形貌及热行为进行了表征,结果表明晶须样品的分散性好,粒度分布均匀、表面光滑,Al3(SO4)2(OH)5H2O与α-Al2O3晶须品质优良.又从“生长基元”角度出发,讨论了Al3(SO4)2(OH)5H2O晶须的形成机制,其生长过程是生长基元是八面体[Al-(OH)6]3-与HSO4-往某一晶面稳定叠合生长的结果,Al3(SO4)2(OH)5H2O晶须经热分解后,其形貌不变,最终变为α-Al2O3晶须.     

基于组装合成的(NH_4)_2[B_(10)O_(14)(OH)_4]·H_2O的结构及其合成机理的初步探讨

基于组装合成的思想,在水热条件下合成了一种水合铵硼酸盐.将孤立的硼氧聚阴离子通过聚合脱水自组装形成一维链状结构,链与链之间通过氢键作用形成硼酸盐层,铵离子和水分子填充在阴离子的骨架间隙中,并通过氢键将硼酸盐层连接起来.使用红外光谱、元素分析、热重-差热分析及X射线单晶衍射分析等手段,对该化合物结构进行了表征.单晶结构分析结果与假想结果相吻合,该化合物系孤立的五硼氧聚阴离子通过缩聚脱水形成一维无限链状结构,链与链之间通过氢键连接在一起,铵离子和水分子填充在骨架间隙当中.该化合物属三斜晶系,P-1空间群,晶胞参数a=0.76413(15) nm,b=0.92529(19) nm,c=1.1949(2) nm,α=99.49(3)°,β=105.87(3)°,γ=91.57(3)°.     

Quantitative determination of fly ash in the hydrated fly ash - CaSO4·2H2OCa(OH)2 system

For the quantitative determination of fly ash in hydrated fly ash - CaSO₄·2H₂OCa(OH)₂ system, various kinds of selective dissolution were evaluated using pastes made from a single representative fly ash. Selective dissolution using picric acid-methanol solution was found to be adequate. Selective dissolution using picric acid - methanol + water can also be used, when it is necessary to save time, although rather bigger corrections are needed. Reproducibility of the determination by both methods was found to be satisfactory, as the standard deviation of the measurement was within 0.23 – 0.55%. Several dissolution experiments were also carried out to obtain the basic information related to this technique.     

CaSO4-Ca(OH)2-H2O体系中硫酸根的平衡浓度

测定了25℃时不同pH值下CaSO4-Ca(OH)2-H2O三元体系中SO42-的平衡浓度,考察了Na+离子的影响. 结果表明,pH值在3.0~12.0范围内SO42-平衡浓度最小,为0.01235 mol/L,基本不受pH值的影响;Na+的存在使溶液中SO42-的平衡浓度增大,且二者呈线性关系. 应用Pitzer电解质溶液理论对体系进行了活度修正,计算结果与实验测定结果基本一致. 研究结果为含SO42-工业废水处理提供了一定的理论依据.     

Al掺入来源Al(OH)3和Al2O3对BaAl2O4∶Eu2+发光及余辉调控的影响

本文采用高温固相法分别以Al(OH)3和Al2O3为Al3+的掺入来源合成了BaAl2O4∶Eu2+发光材料.研究表明,掺Al(OH)3样品发明亮的绿光而无余辉,掺Al2O3样品发蓝绿光有较强余辉,其余辉长达455 s.随着Al3+掺入来源Al(OH)3含量的增高,发射光谱发生红移现象.通过热释光谱分析得,Al2O3为原料的样品热释峰强度远远大于Al(OH)3的热释峰,是它的十几倍.这证明Al(OH)3为原料合成的材料内部存在的浅陷阱,对材料基本上没有余辉贡献.掺Al2O3合成的材料内部的深陷阱影响了材料发光的衰慢过程,表现为材料具有比较长的余辉持续时间.通过Al3+的掺人形式及浓度的控制可以做到对BaAl2O4∶Eu2+发光材料长余辉的调控,是很有应用潜力的发光材料.     

有机模板硼酸盐[C2H8N][B5O6(OH)4]的合成及发光性能研究

以二甲胺和硼酸为原料,通过水热反应合成有机模板硼酸盐[C2H8N][B5O6 (OH)4],通过单晶X射线衍射对其晶体结构进行分析,该晶体属于单斜晶系,空间群为C2/c,晶胞参数为a=1.3381(75) nm,b=1.1468(56)nm,c=1.7137(92) nm,α=90.032(64)°,β=112.292(82)°,γ=89.988(85)°,V=2.433(2.000) nm3.粉末衍射(PXRD),红外(IR),热重(TGA)以及荧光(PL)等手段对其晶体进行分析表征.在不同温度下对该物质进行热处理,观察其IR和PXRD的变化判断其内部的结构是否能够保持稳定,并通过热重分析进行补充说明.荧光光谱结果表明在经过不同温度热处理后,该物质的发光特性发生明显的变化.实验证实[C2H8N] [B5O6(OH)4]一种可能用在白光LED上的荧光粉.     

The Electrical Properties of Polyaniline (PANI)–Co0.5Mn0.5Fe2O4 Nanocomposite

Polyaniline (PANI)/cobalt-manganese ferrite, PANI/Co_0.5Mn_0.5Fe₂O₄, nanocomposite was synthesized by oxidative chemical polymerization of aniline in the presence of ammonium peroxydisulfate. Microwave assisted synthesis method was used for the fabrication of core Co_0.5Mn_0.5Fe₂O₄ nanoparticles. The presence of PANI on the surface of the Co_0.5Mn_0.5Fe₂O₄ NPs was confirmed by infrared spectroscopy and thermal gravimetric analysis. The crystallite size was calculated with line profile fitting method as 20 ± 9 nm. The spherical morphology of the product was presented by Scanning electron microscopy and transmission electron microscopy. The electrical characterizations showed that ac conductivity is found to be independent of frequency and increases with increase of temperatures. However, imaginary component of dielectric function obey the power law of frequency while it is almost independent of temperature. This can be attributed to the molecular interatomic interaction between Co_0.5Mn_0.5Fe₂O₄ nanoballs and PANI shells.     

CH⋯O,OH⋯O and π⋯π interactions in the crystal structure of a new heterotrinuclear macrocyclic complex, [MnII(NiIIL)2(C2H5OH)2](ClO4)2

The title complex was synthesized and characterized by X-ray crystallography. Mn^II ion is in a distorted octahedral environment. The coordination geometries around two Ni^II ions are completely same and are slightly distorted square planar. Mn^II and each Ni^II are bridged by an oxamido-group from one of the two macrocyclic ligands (L). CH⋯O, OH⋯O and π⋯π interactions link the trinuclear fragments and perchlorate ions to form a 3-D supramolecular architecture.     

Synthesis and characterization of [NBu4][La(CH3OH)2(DCU)NO3{Mo5O13(OMe)4(NO)}]·CH3OH: A novel Lanthanide-substituted Lindqvist-type oxo-nitrosyl polymolybdate

A 1:1 complex of Lanthanide-substituted Lindqvist-type oxo-nitrosyl polymolybdate [NBu₄][La(CH₃OH)₂(DCU)NO₃{Mo₅O₁₃(OMe)₄(NO)}]·CH₃OH (1) has been successfully synthesized by a one-pot self-assembly process of hydroxylamine hydrochloride with octamolybdate, DCC and La(NO₃)₃ in methanol under mild reaction conditions. The structure is determined by X-ray crystallography. It is notable that the compound is a Lindqvist-type POM with a capped lanthanum ion which is nine coordinated in a distorted square antiprism geometry. Interestingly, NO₃⁻ as the precursor, as well as the hydrated product DCU of DCC, are both coordinated with Lanthanum ion. The structure has also been characterized by IR, UV–vis and photoluminescence analysis. Photoluminescence analysis reveals that compound 1 emits weak green light in CH₃CN, with the maximum emission at 530 nm.     

α-Fe2O3/Ni3[Ge2O5]·(OH)4复合材料的制备及光催化性能

以FeCl_3·6H_2O和Ni_3[Ge_2O_5]·(OH)_4为原料,通过水浴辅助液相沉积法一步制备了α-Fe_2O_3/Ni_3[Ge_2O_5]·(OH)_4纳米复合材料,利用X射线衍射(XRD)、场发射扫描电子显微镜(FE-SEM)、高分辨透射电镜(HTEM)、紫外-可见吸收光谱(UV-Vis)等表征手段对样品的物相组成、形貌、尺寸及光吸收特性等进行了分析表征。在自然光、室温条件下,以罗丹明B溶液的催化脱色降解为模型反应,探究了不同α-Fe_2O_3负载量对纳米α-Fe_2O_3/Ni_3[Ge_2O_5](OH)_4复合材料降解罗丹明B性能的影响规律。结果表明,利用该法可以得到纳米级的、相互之间紧密复合的α-Fe_2O_3/Ni_3[Ge_2O_5](OH)_4复合材料;当复合材料中α-Fe_2O_3与Ni_3[Ge_2O_5]·(OH)_4的质量比为1:10时得到的纳米复合材料在氙灯光照条件下具有最佳的催化性能,180 min脱色率可达89.35%。是相同条件下α-Fe_2O_3脱色率的11.6倍。     

Mg4(Mb2-xSbx)O9陶瓷的制备与微波介电性能

采用传统固相反应法制备了Mg4(Nb2-xSbx)O9陶瓷,研究了该材料的烧结性能、物相结构、显微组织和微波介电性能.X射线衍射结果显示,在x小于或等于1.6的范围内,形成了具有α-Al2O3刚玉型晶体结构的连续固溶体,晶轴长度和晶胞体积均随着锑含量的增加而降低.在x等于2.0时,Mg4Sb2O9的物相结构发生了变化,晶轴长度和晶胞体积也发生了突变.当0.4≤x≤O.8时,陶瓷的烧结温度从1400℃降低到了1300℃;而当x≥1.2后,陶瓷的烧结性能和微波介电性能均降低.在1300℃,5h的烧结条件下,Mg4(Nb1.6Sb0.4)O9陶瓷的微波介电常数(εr)为12.26,Q·f为168450 GHz.     

Molecular structure design based on Lewis acid–base interaction in the preparation of bimetallic alkoxides derived from two electronegative elements. The synthesis and X-ray single crystal study of Mo2Ta4O8(OMe)16 and Mo4Ta2O8(OiPr)14

Complex formation between molybdenum and tantalum alkoxides has been achieved via activation of the homometallic species, both being Lewis acids, by either partial hydrolysis or partial thermolysis in hydrocarbon media. The crystal structures of the products formed, Mo₂Ta₄O₈(OMe)₁₆ (I) and Mo₄Ta₂O₈(OⁱPr)₁₄ (II) respectively, are described.     

Li2Zn3(1-x)Ca3xTi4O12微波陶瓷介电性能研究

本文以Li2CO3,ZnO,CaCO3,TiO2为原料,采用固相反应法制备了Li2Zn3(1-x)Ca3xTi4O12(x=0,0.05,0.1,0.15)陶瓷,并研究了CaTiO3固溶量对其显微结构和微波介电性能的影响.结果表明:Li2Zn3Ti4O12晶相中固溶CaTiO3相,晶胞参数会增大;少量CaTiO3相固溶于Li2Zn3Ti4O12陶瓷后,提高了Li2Zn3Ti4012陶瓷的烧结温度及其介电常数,但降低了其品质因素,可增大其温频系数.在1100℃/2 h烧结条件下,Li2Zn2.7Ca0.3Ti4O12陶瓷微波介电性能达到:εr=24,Q×f=50000 GHz,Tf=-25×10-6/℃.