变性淀粉在铝硅矿物浮选分离中的作用机理

通过浮选实验、动电位和红外光谱测定,详细考察了变性淀粉在铝硅矿物浮选分离中的作用效果和机理。浮选实验显示：非离子淀粉和阴离子淀粉在pH＜6时,抑制一水硬铝石的浮选,但当pH＞6时,却对一水硬铝石浮选有活化作用;阳离子淀粉在较宽pH值范围内对一水硬铝石均有抑制作用;3种淀粉化合物在pH＜6时均活化高岭石的浮选,当pH＞6时活化作用较微。结果表明：变性淀粉是一水硬铝石型铝土矿反浮选中实现一水硬铝石和高岭石分离的有效调整剂,阴离子淀粉使矿物表面ζ电位更负,阳离子淀粉使矿物质表面ζ电位更正,非离子淀粉使矿物表面电位绝对值减小。由实验结果结合药剂与矿物作用前后的红外光谱分析,得出结论：非离子淀粉主要通过氢键作用吸附于矿物表面,而静电力和化学键合力在阴离子淀粉和阳离子淀粉吸附中发挥着重要作用。     

KINETICS OF COPPER EXTRACTION BY N530-HEPTANE

The activity coefficients of all the components in H_2SO_4-CuSO_4 solution were calculated by using Pitzer's equation.Six Pitzer's mixing parameters μ and were evaluted.The change of the activity and concentration of the ions during extraction was measured by drop weight method.The interfacial excesses of all the components were calculated from the interfacial tension equation which is expressed in terms of activities of every components.Results show that H~+ and Cu~(2+) are positively adsorpted by CuR_2,(HR)_2 ,SO_4~(2-) and HSO_4~- are negatively adsorpted on the interface.     

NaOH-NaAl(OH)4-Na2CO3-H2O体系活度因子的计算模型

应用Bromley模型,通过对氢氧化钠、铝酸钠和碳酸钠等溶液体系活度因子的实验数据进行校验与回归分析,获得了各电解质合理的Bromley参数,建立基于Bromley模型的NaOH-NaAl(OH)4-Na2CO3-H2O体系活度因子的计算模型,其适用范围为:质量摩尔浓度分别为m(NaOH)≤8 mol/kg,m(NaAl(OH)4)≤3 mol/kg,m(Na2CO3)≤3 mol/kg且离子强度I≤9 mol/kg.使用该模型和Rard方法计算所得水的活度比较结果表明:该模型正确有效,计算精度较高,各电解质的Bromley参数取值合理;该模型也可用于NaOH-NaAl(OH)4-H2O体系活度因子的计算.     

Wet spinning of pre-doped polyaniline into an aqueous solution of a polyelectrolyte

We report the preparation of highly conductive polyaniline (PANi) fibers produced via a wet-spinning process into different coagulation solvents or solutions. To the best of our knowledge, this paper shows the first successful spinning of PANi fibers into an aqueous environment where no post-doping of the fiber is needed. Aqueous solutions of different salts, small anionic molecules, small cationic molecules, polycations, and polyanions are studied. Best results are obtained using an aqueous solution of a polyanion as a coagulation bath. The resulting fibers exhibit good length, stability, and morphology. An in depth study of the relationship between the fiber properties and the concentration of a polyanion in the aqueous bath (poly(sodium 4-styrenesulfonate), PSS) is performed. It is shown that PSS solutions stabilize the PANi fibers without dramatically changing the conductivity of the fibers. It is believed that this stabilization is a result of numerous ionic interactions between cationic centers on the PANi and anionic groups on the polyanion. This new preparation method should be industrially viable.     

Effects of acidity,temperature and surfactants on electrochemical behavior of V~(5+) ion in sulfuric acid solutions

1　INTRODUCTIONSeveralredoxcouplesincludingCe4 +/Ce3+,Mn3+/Mn2 +,Co3+/Co2 +andV5+/V4 +etchaveat tractedmuchattentioninindirectelectrosynthesisofsomeorganiccompoundsandinmediatedelectro chemicaloxidationofbenzene ,aniline ,phenolandchlorinatedorganicsetc[17] .Electrochemicalbehav ioroftheredoxcoupleCe4 +/Ce3+hasbeenstud ied[8,9] .Beingstrongandselectiveoxidizingagents ,vanadiumsalts ,comparedwithcoppersalts ,weremoreefficienttocatalyzetheoxidationoftoluenetobenzaldehydeviaelectrochemica…     

冷却工艺对抗大变形管线钢X70HD热涂敷性能的影响

抗大变形管线钢加热并保温一段时间后,钢管力学性能将发生变化,通常屈服强度、屈强比升高,均匀延伸率降低,应力-应变曲线形状改变等,这些性能变化将降低钢管的抵抗变形的能力。利用扫描电镜等设备研究了冷却工艺对21 mm X70HD抗大变形管线钢组织、性能和应变时效硬化的影响。结果表明,随开始冷却温度的降低,先共析铁素体含量逐渐增加,贝氏体含量逐渐降低,贝氏体由粒状逐渐向板条状转变,当开始冷却温度在700℃时,钢板具有最佳的综合力学性能,试验钢板通过制成1016 mm钢管,钢管在200℃时效保温5 min下,纵向屈服强度Rt0.5为509 MPa,抗拉强度Rm为692 MPa,延伸率为42%,屈强比Rt0.5/Rm为0.73,Rt1.5/Rt0.5为1.19、Rt2.0/Rt1.0为1.10,均匀变形伸长率达到9.5%。     

Synthesis and characterization of polythiophenes prepared in the presence of surfactants

In this study homopolymers of thiophene were synthesized by chemical oxidative polymerization in the presence of three different surfactants (anionic, cationic and non-ionic) and an oxidant in an anhydrous medium. An anionic surfactant, sodium dodecylbenzenesulfonate (DBSNa), a cationic surfactant, tetradecyltrimethylammonium bromide (TTAB) and a non-ionic surfactant, poly(ethylene oxide) (20) sorbitan monolaurate (Tween 20), were used as additives. The properties of the polythiophenes (PTs) prepared were studied and compared with those of surfactant-free polythiophene (PT). PTs were characterized by different techniques: FTIR spectroscopy, elemental analysis, scanning electron microscopy, thermogravimetry and conductivity measurement. The scanning electron micrographs of PT prepared in the presence of surfactants showed differences in the surface morphologies for different surfactants. PT prepared in the presence of cationic and non-ionic surfactants exhibited smooth surfaces, while a typical globular structure was found for surfactant-free PT. PT synthesized with a cationic surfactant showed the highest thermal stability of all the samples.     

Thermoelectric properties of rare earth doped SrTiO3

The thermoelectric properties of Sr_0.9R_0.1TiO₃ (R=Y, La, Sm, Gd, Dy) have been measured from room temperature to 1073 K. The electrical conductivities and Seebeck coefficients are independent of the kind of rare earth elements in the temperature range, so the figure of merits are influenced by the difference in the thermal conductivities. The thermal conductivities decrease with doping according to the rare earth atomic mass and ionic radius. Sr_0.9Dy_0.1TiO₃ shows the highest figure of merit of the investigated samples, reaching 3.84×10⁻⁴ K⁻¹ at 573 K.     

New electrolytes for aluminum production: Ionic liquids

In this article, the reduction, refining/recycling, and electroplating of aluminum from room-temperature molten salts are reviewed. In addition, the characteristics of several non-conventional organic solvents, electrolytes, and molten salts are evaluated, and the applicability of these melts for production of aluminum is discussed with special attention to ionic liquids. Also reviewed are electrochemical processes and conditions for electrodeposition of aluminum using ionic liquids at near room temperatures. For more information, contact R.G. Reddy, the University of Alabama, Department of Metallurgical and Materials Engineering, Center for Green Manufacturing, A-129 Bevill Building, 126 Seventh Avenue, Tuscaloosa, Alabama 35487; (205) 348-4246; fax (205) 348-2164; e-mail rreddy@coe.eng.ua.edu.     

Q345E- Z35特厚板Z向性能不合原因分析

针对正火态Q345E- Z35特厚板Z向性能不合问题,采用金相检验、扫描电镜等检测手段,对Z向拉伸断口形貌及断口处夹杂物进行了分析。结果发现：导致特厚板Z向性能不合格的主要原因是中心部位存在带状组织偏析,以及长条的硫化锰夹杂、Nb/Ti块状夹杂和Si/Mn球状夹杂。为此,提出控制钢水中S含量,保证合理的板坯浇铸速度,优化加热、控轧和正火工艺等措施,改善了特厚板的Z向性能。     

THE HOT DEFORMATION BEHAVIOR AND DYNAMIC RECRYSTALLIZATION MODEL OF 35CrMo STEEL

The isothermal single-stage compression of 35CrMo structural steel has been carried out by using Gleeble 1500 simulator at the temperature range of 950℃ to 1150℃ and strain rate range of 0.01s-1 to 10s-1. The effect of hot deformation parameters, such as strain rate, deformed temperature and initial grain size on the flow stress behavior was investigated. The activation energy of tested alloy was calculated, which is 378.16kJ/mol; The relationships between the peak stress (σp), the peak stain (εp), the critical strain (εc) and Z parameter were established. The micro structure evolution shows the pre-existing austenite grain boundaries constitute the principal nucleation sites for dynamic recrystallization (DRX), and the initial austenite grain size affects the grain size of DRX slightly. The kinetic mathematical model of DRX of 35CrMo is: XDRX=1-exp(-3.23-2.28) and Ddyn = 2.252× 10Z-0.22.     

Rotational motion of polyanion versus volume effect associated with ionic conductivity of several solid electrolytes

Volume effect has been extensively investigated in several families of solid electrolytes, i.e., expanding the skeleton lattice by bigger-size substitution favors the ionic conduction. However, this effect is not applicable in a-Li_2SO_4 and a-Na_3PO_4 based inorganic ionic plastic crystal electrolytes, a unique family of solid electrolytes. Here, it is proposed that the underlying rotational motion effect of polyanion, which is actually inhibited by the substitution of bigger-size polyanion in single-phase solid solution region and causes the unexpected lowering of the ionic conductivity instead, should need the more consideration. Furthermore, through utilizing the rotational motion effect of polyanion, it is given that a new explanation of the ionic conductivities of Li_(10)MP_2S_(12)(M = Si, Ge, Se) electrolytes deviating from the volume effect. These results inspire new vision of rationalization of the high-performance solid electrolytes by tuning the rotational motion effect of polyanion.     

Solvent Economy in Trichlorethylene Degreasing Plants

Using HE9 material (an aluminium—magnesium silicon alloy) the anodic reactions of a number of water-soluble organic caboxylic acids not generally described in the literature are summarized, with and without small additions of oxalic acid. The electrolytic processes are related to the strength (conductivity and acidic dissociation constants) of the acid electrolytes, both singly and in combination with oxalic acid, together with the general chemical properties of the ionic species involved. The reason for the production of integrally coloured coatings using some of the electrolytes is discussed and the properties of some of the thicker films obtained summarized.     

Sum-rule relationships among phenomenological coefficients: Simplifications for the analysis of segregation and chemical diffusion

In this review article, the authors first introduce the phenomenological transport coefficients, and the relationships between them and the tracer diffusion coefficients. Next, the authors discuss a sum rule relating phenomenological coefficients themselves in the random-alloy model. The authors then consider several applications of the sum rule to diffusion problems. These applications include intrinsic diffusion in multicomponent alloys, chemical diffusion in strongly ionic mixed cation crystals, and the segregation (demixing) of cations in mixed oxides in an oxygen potential gradient and/or an electric field. In each case, a substantial simplification is possible as a result of the sum rule.     

Inhibition effect of some surface active agents on dissolution of copper in nitric acid

Abstract

The inhibitive efficiency of some nonionic, amphoteric, cationic, and anionic surface active agents (surfactants) on the dissolution of copper in 4·5M HNO₃ was studied at 25°C by the weight loss method. The percentage inhibition I increases as the concentration of the cationic, nonionic, and amphoteric substances increases and reaches a limiting value. It is suggested that this is due to the formation of a monolayer on the surface of the metal; the Langmuir adsorption isotherm was confirmed. In the case of anionic surface agents, the percentage inhibition values were at their highest at low surfactant concentrations and decreased as the concentration of the surfactant increased.     

表面活性剂对镀Ti金刚石-Ni复合电沉积行为的影响

研究了阴离子表面活性剂十二烷基硫酸钠(SDS,sodium dodecyl sulfate)和阳离子表面活性剂十六烷基三甲基溴化铵(CTAB,cetyl trimethyl ammonium bromide)对镀Ti金刚石-Ni复合电沉积的影响,并结合循环伏安、交流阻抗等电化学方法研究了镀Ti金刚石-Ni镀液中Ni电沉积过程。结果表明:与未镀覆金刚石相比,镀Ti金刚石与Ni层浸润性得到提高。浓度为0.05 g/L的SDS对Ni电结晶过程有抑制作用,而浓度为0.05 g/L的CTAB能促进Ni~(2+)离子转移并加快Ni的电沉积过程。SDS和CTAB都能促进电沉积过程中氢气的析出并细化Ni镀层,同时减少镀层针孔和凹痕。     

Rare earth contribution in solid state electrolytes, especially in the chemical sensor field

In solid state electrolytes, rare earths are commonly used, and a number of their properties are exploited in these applications. Firstly, the rare earth can be utilized as a dopant to produce the mobile ion vacancies in an electrolyte and to enhance the ionic conducting characteristics. Secondly, they can be used as the principal constituent of the electrolytes. In both these case, the characteristics that the rare earths hold a stable trivalent state even though the main ionic mobility is via mono- or trivalent ions. Thirdly, the rare earth trivalent ion alone can migrate in some solids. This unexpected feature has been recently clarified by selecting the appropriate structure for the trivalent ion conduction in order to reduce the electrostatic interaction between the mobile ions and the framework of the solid. In solid electrolytes, only one ionic species can migrate. This feature is very advantageous for chemical sensor applications, especially from the viewpoint of selective and quantitative detection of specific gas species. The rare earth contribution to solid state electrolytes has been rapidly increasing, and has been expanding further the realms of application not only in the industrial field but also in the whole science field. Here, the rare earths contribution to the solid state electrolyte field is briefly reviewed.     

铝土矿选矿尾矿性质及沉降性能研究

采用沉降法研究了细粒铝土矿选矿尾矿在水介质中的絮凝行为，考查了pH值、阳离子型、阴离子型和非离子型聚丙烯酰胺有机高分子絮凝剂及阴离子型絮凝剂的分子量变化对细粒尾矿沉降性能的影响。测试了加入絮凝剂前后颗粒表面Zeta电位、界面高度的变化。结果表明，介质pH在7～7．2时，阴离子型聚丙烯酰胺对细粒尾矿的絮凝效果最好；阳离子型和非离子型聚丙烯酰胺对细粒尾矿的絮凝效果较差；阴离子型聚丙烯酰胺的最佳药剂用量为25g／t。     

Preparation of TiO2/PANI composites in the presence of surfactants and investigation of electrical properties

“In situ” polymerization was carried out in the presence of titanium dioxide (TiO₂) to synthesize TiO₂/polyaniline (TiO₂/PANI) composite in an aqueous medium containing anionic (sodium dodecylbenzenesulfonate), DBSNa, cationic (tetradecyltrimethylammonium bromide), TTAB, and nonionic surfactants (poly(ethylene oxide) (20) sorbitan monolaurate), Tween 20). The composites were characterized by FTIR, UV–vis spectroscopy, scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Gouy balance measurements. The FTIR and UV–vis spectra reveal that the interaction between TiO₂/PANI composite and surfactants. The anionic and cationic surfactants incorporated with TiO₂/PANI composite structure. The stability of the composites in terms of direct-current electrical conductivity retention was studied in isothermal conditions. Electrical conductivity measurements indicate that the conductivity of TiO₂/PANI synthesized in the presence of the cationic surfactant has the highest conductivity value. All composites showed negative mass magnetic susceptibility values.     

Gel electrolytes containing several kinds of particles used in quasi-solid-state dye-sensitized solar cells

Composite gel electrolytes containing several kinds of particles used as the quasi-solid-state electrolytes in dye-sensitized solar cells (DSSCs) were reported. Mesoporous particles (MCM-41) with unique structures composed of ordered nanochannels were served as a new kind of gelator for quasi-solid-state electrolytes. MCM-41, hydrophobic fumed silica Aerosil R972 and TiO2 nanopatricles P25 were dispersed into gel electrolytes respectively. The solar energy-to-electricity conversion efficiency of these cells is 4.65%, 6.85% and 5.05% respectively under 30 mW·cm-2 illumination. The preparation methods and the particles sizes exert an influence on the performance of corresponding solar cells. Owing to unique pore structures and high specific BET surface area, mesoporous silica MCM-41 was expected to have the potential to afford conducting nanochannels for redox couple diffusion.