Bi(Ⅲ)在NaCl-KC1熔盐体系中的电化学行为

为开发环境友好型铋提取技术,在700℃下采用循环伏安、方波伏安和计时电位等方法研究了NaCl?KCl熔盐体系中Bi(III)在玻碳电极上的电化学行为。在–0.3 V (vs. Ag/AgCl)电位下以玻碳电极为工作电极对NaCl?KCl?BiCl3进行恒电位电解。结果表明,Bi(III)在NaCl?KCl熔盐体系中的还原反应是一步得到3个电子的准可逆反应Bi3++3e?=Bi,起始还原电位为0.05 V (vs. Ag/AgCl),该反应受扩散控制。Berzins-Delahay方程和Sand方程计算的700℃下Bi(III)在熔盐中的扩散系数分别为0.83×10–5和1.0×10–5 cm2/s。阴极产物为致密纯金属Bi,不含杂质。     

Bi(Ⅲ)在NaCl-KCl熔盐体系中的电化学行为

为开发环境友好型铋提取技术,在700℃下采用循环伏安、方波伏安和计时电位等方法研究了NaCl-KCl熔盐体系中Bi(Ⅲ)在玻碳电极上的电化学行为。在–0.3 V (vs. Ag/AgCl)电位下以玻碳电极为工作电极对NaCl-KCl-BiCl_3进行恒电位电解。结果表明,Bi(Ⅲ)在NaCl-KCl熔盐体系中的还原反应是一步得到3个电子的准可逆反应Bi3++3e-=Bi,起始还原电位为0.05 V (vs. Ag/AgCl),该反应受扩散控制。Berzins-Delahay方程和Sand方程计算的700℃下Bi(Ⅲ)在熔盐中的扩散系数分别为0.83×10~(–5)和1.0×10~(–5) cm~2/s。阴极产物为致密纯金属Bi,不含杂质。     

高碳铬铁盐酸浸出过程工艺及动力学

传统铬盐行业生产过程中铬的价态需经过三价到六价再到三价的转化。六价铬的高毒性导致铬成为国家重点防控的重金属。铬盐行业的可持续发展亟需开发避免六价铬产生的新技术，含铬原料的酸浸为可行的途径。本文提出以高碳铬铁合金为原料，盐酸为浸出剂的酸性浸出制备三价铬盐新工艺。浸出后的氯化铬和氯化亚铁可制备出三价铬盐产品，其可作为铁铬液流电池的电解液。本文在对高碳铬铁元素含量、物相组成及形貌等分析的基础上，系统研究了反应温度、盐酸浓度、搅拌速率和反应时间对铬和铁浸出率的影响规律。结果表明，在反应温度100℃、盐酸浓度9mol/L、搅拌速率250r/min、反应时间6h的条件下，铬浸出率为92%，铁浸出率为95%。进一步研究了高碳铬铁在盐酸中浸出的动力学。高碳铬铁的浸出过程符合未反应收缩核模型，铬浸出过程受化学反应控制，表观活化能E_a=65.95kJ/mol；铁浸出过程受化学反应控制，表观活化能E_a=63.85kJ/mol。     

SiO2对CaCl2熔盐电解还原钛铁矿精矿制备FeTi合金的影响

在不同电解时间和槽电压下,添加SiO2电解还原钛铁矿精矿制备钛铁合金. 结果表明,以添加一定量SiO2的钛铁矿精矿为阴极,控制阴极中主要组元的摩尔比Ti:Fe:Si=1.2:1:0.2,以石墨棒为阳极、CaCl2熔盐为电解质,在槽电压3.2 V、温度900℃下电解2 h,可制得疏松多孔、颗粒尺寸较均匀的FeTi合金粉体. 钛铁矿精电解还原过程中会生成CaTiO3和Fe?Ti?O等中间产物,添加的SiO2在电解时会优先还原生成单质Si,并参与CaTiO3等中间产物的还原反应,降低中间产物电解还原生成FeTi合金的理论电压,有利于加快电解还原钛铁矿精矿制备钛铁合金的速率.     

NiFe2O4/Ag惰性阳极的熔盐腐蚀性能

以Fe2O3,NiO和Ag粉为主要原料,采用固相烧结工艺制备了NiFe2O4/Ag惰性阳极.采用X射线衍射和扫描电子显微镜对材料的组成和微观结构进行了研究,并测量了样品抗热震性、抗折强度、在冰晶石熔盐中的静态热腐蚀以及电解腐蚀速率,对其腐蚀过程作了初步探讨.结果表明:惰性阳极由NiO,NiFe2O4尖晶石和Ag三相组成.随着金属Ag含量的增多,惰性阳极样品在冰晶石熔盐中的静态热腐蚀速率增加,由于抗热震性和抗折强度有了大幅提高,电解腐蚀速率降低.静态热腐蚀和电解腐蚀呈现出物理化学溶解过程,而且由于金属银对晶界的强化作用,电解腐蚀由晶粒开始.     

CaCl2–TiCl2熔盐体系中制备高纯钛

以海绵钛为阳极,纯钛板为阴极,钛离子质量分数为3%~8%的CaCl2–TiCl2混合熔盐作电解质,在温度为1 173 K,阴极电流密度为0.05~0.80 A/cm2的条件下,电解制备了高纯钛。研究了阴极电流密度和钛离子质量分数对阴极电流效率和产物中杂质含量的影响,确定了最佳精炼条件为:阴极电流密度为0.50 A/cm2,钛离子质量分数为6%,电解温度为1 173 K。原料钛的纯度约为98.65%,经优化条件电解后钛的纯度可提高至99.95%。通过扫描电镜对不同电解条件下所得产物形貌进行了表征。     

乏燃料熔盐电解后处理动力学模型研究

电解精炼是乏燃料干法后处理工艺中的关键环节。针对氯化锂-氯化钾（LiCl-KCl）熔盐环境中的电解精炼行为,基于电极表面处的反应过程建立了动力学模型。通过与现有实验数据的比较验证了模型的有效性。通过该模型,可以预测电解精炼过程中液镉阳极中乏燃料的溶解和阴极处金属沉积的动力学特征,以及所涉及元素的分电流、电极电位和熔盐中离子浓度的演变。除此之外,该模型还能模拟多元素复杂体系电解精炼的过程。当使用锆、铀、钚及稀土作为阳极时,模拟结果显示在阳极处锕系元素和稀土元素随时间逐渐溶解,而惰性金属几乎不溶解。在熔盐中,钚的浓度逐渐增加而铀的浓度逐渐减少,当钚开始在固体阴极发生沉积后,铀的沉积速率减小,而稀土元素和锆在阴极的沉积量极少。     

SOM法与FFC法制备海绵钛的对比

对固体透氧膜法(SOM)与熔盐电解法(FFC)直接电解还原制备金属钛进行了对比研究。SEM与EDX分析表明,产物呈海绵结构,电解时间延长,氧含量降低,颗粒尺寸增加;FFC法需电解9 h,TiO2阴极片才会被还原为金属钛;SOM法使用透氧膜隔离阴极与阳极,避免了副反应发生,只需电解3h即可获得金属钛;分析了SOM法电解过程氧离子的迁移行为。     

熔盐电解磁搅拌-真空蒸馏联合法制备多晶硅

以高纯二氧化硅为原料,高纯石墨为阳极,磁场中旋转的镁锌合金为阴极,电解制备镁硅锌合金.通过真空蒸馏分离合金得到了纯度较高的多晶硅.采用熔盐电解监控仪和Teslmcter对电流密度、槽电压、反电动势和磁场强度参数进行测量,研究了电磁搅拌在阴极合金反应过程中的作用,电解过程中的反电动势、电流效率及产物硅浓度的变化.结果表明...     

一种高碳铬铁的生产方法

本发明涉及一种用固体碳质还原剂生产高碳铬铁的方法。采用铬铁矿粉、铁矿粉、煤粉或焦粉、消石灰、硅石粉等原料，通过混匀、压块或造球、干燥后在1350～1500℃高温下还原。还原产物在冷却过程中自然粉化，通过筛分将铬铁颗粒从渣子中分离出来。     

化学激发对微碳铬铁粉渣胶凝性能的影响

采用化学激发的手段来提高微碳铬铁粉渣的早期活性及微碳铬铁粉渣制品的强度。研究结果表明:激发剂Na_2CO_3、Na_2SO_4、硫铝酸盐水泥对于微碳铬铁粉渣浆体均具有比较好的调凝作用,激发剂Na_2CO_3、Na_2SO_4、普通硅酸盐水泥对于微碳铬铁粉渣发泡浆体的强度均有激发作用,以Na_2CO_3的效果最好。复掺Na_2CO_3和普通硅酸盐水泥,微碳铬铁粉渣发泡浆体的强度较单掺有显著提高,通过选择适当的配比,可以配置出符合工程需要的微碳铬铁粉渣发泡砌块。     

Oxygen and hydrogen peroxide reduction catalyses in neutral aqueous media using copper ion loaded glassy carbon electrode electrolyzed in ammonium carbamate solution

An aminated glassy carbon electrode (AGCE) can be obtained by the electrode oxidation of glassy carbon electrode in ammonium carbamate solution. In the cyclic voltammetric experiments, the electrode reduction of the dissolved oxygen began from −0.15 V vs. Ag/AgCl in neutral aqueous media when the aminated glassy carbon electrode was used as a working electrode although it began from −0.40 V vs. Ag/AgCl when a polished GCE was used. The nitrogen containing groups introduced by the electrode oxidation of carbamic acid must be related with the acceleration of the electron transfer rate of oxygen. Moreover, the new reduction wave of the dissolved oxygen appeared at +0.15 V vs. Ag/AgCl when copper (II) ion was coordinated to AGCE surface. This reduction potential of oxygen coincided with that of copper (II) ion and this fact suggests that the coordinated copper ion to the aminated carbon surface works as a redox mediator of oxygen. The reduction product of oxygen was monitored by rotating platinum ring - aminated glassy carbon disk electrode, and it was found that most of oxygen was reduced to water in a potential range negative than −0.4 V vs. Ag/AgCl. By using AGCE, it was recognized that the catalytic reduction of hydrogen peroxide was also taken place as well as oxygen reduction.     

氧化物电还原体系银/氯化银参比电极性能研究

参比电极的研究是高温熔盐电化学必不可少的环节之一。以莫来石作为Ag/AgCl电极隔膜材料,制备了可用于在650 ℃的LiCl熔盐体系中开展氧化物电化学还原实验的Ag/AgCl参比电极。采用开路电位法考察了电极活化时间、可逆性、耐极化性、稳定性及重现性等性能。例如,初次使用的参比电极要经过2 h活化才能达到电位稳定。给予微弱电流后参比电极会发生极化,但极化电位基本能在断电后的几分钟内消除。结果表明,莫来石隔膜Ag/AgCl参比电极具有活化时间短、温度对电极可逆性影响小、耐极化性能、电位稳定性、平行性及重现性良好等特点。该参比电极的研制为将来开发性能更加稳定的可用于高温熔盐氧化物电化学还原的参比电极提供了一定的指导意义。     

电活化玻碳电极作为苯酚伏安传感器的研究

玻碳电极在0.5mol.L-1硫酸溶液中以恒电位法在＋1.7V（vs.Ag/AgCl）电位阳极氧化400s得到电活化玻碳电极。采用循环伏安法和差分脉冲伏安法对苯酚在电活化玻碳电极上的电化学行为进行了研究。结果发现,在pH值7.0的磷酸盐缓冲溶液中,苯酚在0.75V（vs.Ag/AgCl）处有一良好的氧化峰,在0.02～0.10V.s-1范围内,其氧化峰电流与扫描速率呈良好线性关系,表明电极过程为受吸附控制的不可逆过程;氧化峰电流（Ip）与苯酚浓度在1×10-6～1×10-4 mol.L-1范围内呈良好的线性关系（R=0.9852）,检出限为6.0×10-7 mol.L-1（S/N=3）。并应用此法分析了自来水中苯酚的含量。     

Methode nouvelle et aisee d''obtention des electrodes Ag, AgCl/Cl

A method of producing an Ag, AgCl/C⁻ electrode by means of an adsorption cell is described. This cell contains 1 N hydrochloric acid solution into which two electrodes are immersed: a silver rod or platinum rod covered with silver and a carbon powder electrode formed with active carbon compressed into cylindrical shape. The electromotive force of the cell is determined by the adsorption of protons on the active carbon and by the chemisorption of chloride ions on the silver. During the work of this cell, its negative electrode is converted into an Ag, AgCl/Cl⁻ electrode having good properties.     

Electrochemical determination of dissolved oxygen based on three dimensional electrosynthesis of silver nanodendrites electrode

In this paper, a highly sensitive electrochemical sensor for dissolved oxygen was prepared. A glassy carbon electrode was modified with silver nanodendrites that were synthesized by electrochemical deposition on the electrode without the use of a surfactant or template. The electrode displayed efficient electrocatalytic reduction of dissolved oxygen to form hydroxy ions via a four-electron reduction pathway, and a significant decrease in the respective overvoltage. The sensor responded linearly to dissolved oxygen in the 1.0–66.7 μM concentration range, and had a remarkably good sensitivity (0.169 μA μM^?1) at an applied potential of ?300 mV (vs. Ag/AgCl). The lower detection limit was 0.043 μM (at the signal-to-noise ratio of 3), and the response time was 5 s. The good performance was attributed to the enlarged electro-active surface of the dendritic silver nanostructures and to the efficiency of electron transfer between dissolved oxygen and the electrode. The sensor also showed good reproducibility, long-term stability, and relative good selectivity.     

用于熔盐体系的氮化硼隔膜Ag/AgCl参比电极性能

介绍了熔盐中常使用的参比电极的性质和存在的问题,制得可用于高温氟化物盐中的氮化硼隔膜Ag/AgCl的参比电极,并对它的性能做了重点研究。确定了AgCl的物质的量分数为2%时较好,且需确保AgCl均匀地混合在LiCl-KCl熔盐中;该种参比电极在制备过程中应注意在各接口处严格密封,以减缓盐的蒸发和导线的腐蚀。对参比电极的性能做了评价,发现活化温度对活化时间有影响;温度变化对电位影响较小;参比电极的极化可逆性均良好;稳定性良好,但是受AgCl浓度、温度及光线的影响,长期使用电极的重现性较好。最终发现该参比电极性质稳定可长期连续（至少28 d）用于熔盐电化学实验中。     

Enhanced Bio-Electrochemical Reduction of Carbon Dioxide by Using Neutral Red as a Redox Mediator

Microbial electrosynthetic cells containing Methylobacterium extorquens were studied for the reduction of CO₂ to formate by direct electron injection and redox mediator-assisted approaches, with CO₂ as the sole carbon source. The formation of a biofilm on a carbon felt (CF) electrode was achieved while applying a constant potential of −0.75 V versus Ag/AgCl under CO₂-saturated conditions. During the biofilm growth period, continuous H₂ evolution was observed. The long-term performance for CO₂ reduction of the biofilm with and without neutral red as a redox mediator was studied by an applied potential of −0.75 V versus Ag/AgCl. The neutral red was introduced into the systems in two different ways: homogeneous (dissolved in solution) and heterogeneous (electropolymerized onto the working electrode). The heterogeneous approach was investigated in the microbial system, for the first time, where the CF working electrode was coated with poly(neutral red) by the oxidative electropolymerization thereof. The formation of poly(neutral red) was characterized by spectroscopic techniques. During long-term electrolysis up to 17 weeks, the formation of formate was observed continuously with an average Faradaic efficiency of 4 %. With the contribution of neutral red, higher formate accumulation was observed. Moreover, the microbial electrosynthetic cell was characterized by means of electrochemical impedance spectroscopy to obtain more information on the CO₂ reduction mechanism.     

ICP-AES法测定低碳铬铁中锰和磷

以电感耦合体原子发射光谱法(ICP-AES)直接同时对低碳铬铁中微量杂质元素Mn、P进行测定,优化了仪器条件,采取加入基体和钇内标校正的方法消除了试液进样的物理化学影响干扰。精密度、标准样品分析对照均取得了满意的结果。