双膜三室电解槽中电沉积金属钴（英文）

对离子交换膜电解槽中电沉积钴的参数进行了优化研究,并探讨了阴极液成分、电流密度、温度等因素对电沉积钴的电流效率、单位能耗、质量的影响规律。阴极液为含氯化钴混合溶液,初始中间液为稀盐酸溶液,阳极液为硫酸溶液。采用阴离子交换膜将阴极液与中间液隔开,阳离子交换膜将阳极液与中间液隔开。结果表明:最佳实验条件为80 g/L钴、20 g/L硼酸、3 g/L氟化钠、pH 4、电流密度250 A/m~2、温度50°C,在该条件下电流效率为97.5%。中隔室可得到电化学再生的盐酸,酸浓度达到0.45 mol/L,实现了产酸抑氯同步化。     

钛材在离子膜电解槽中的应用

在离子膜电解槽中阴、阳极室温度为90℃左右,阳极室有氯气和食盐溶液,阴极室有30～35％(wt)浓度的烧碱溶液,离子膜电解槽一般运行电流密度为30～40A/dm~2。如此苛刻的工况条件,在电解槽设计时,必须充分考虑电解槽的材料使用及防腐结构。离子膜电解     

粉煤灰制氧化铝工艺电解除铁方法探索研究

为满足粉煤灰制氧化铝过程中除铁的工艺要求，研究了离子交换膜电解法去除浸出母液中杂质铁的工艺条件，使用离子交换膜分隔阳极室和阴极室，以FeCl₂溶液为阴极电解液，NaCl溶液为阳极电解液，钛板和石墨分别做阴极和阳极。考察了Fe²⁺初始浓度、电解液pH、电流密度、电解温度等条件对电解除铁效果的影响规律。试验结果表明：Fe²⁺初始浓度对电解除铁效果没有影响；电解液的最佳pH为2.50;电流密度过高会使电解除铁的效率变低，当Fe²⁺初始浓度为3 g/L时，最佳的电流密度为2 A/dm²;温度对低Fe²⁺浓度(<0.4 g/L)电解效率的影响不显著，但Fe²⁺浓度大于0.4 g/L,提高温度可以提升电解除铁速率。     

双膜三室电沉积金属锰联产EMD的离子传输过程

针对传统单槽电解金属锰或二氧化锰存在能耗高、资源利用率低、环境污染严重等问题,提出双膜三室电解法实现阴极电沉积锰同时阳极联产电解二氧化锰,中隔室电化学再生硫酸。通过分析各隔室离子浓度变化,探究双膜三室电解法技术可行性,并对比三种离子交换膜对电沉积效果的影响。结果表明:双膜三室电解法电沉积金属锰同时联产电解二氧化锰可以实现,并且阴极电流效率可达80%以上,阳极电流效率可达60%以上,中隔室酸回收率高于65%;与Ionsep-HC、LANRAN-AM相比,TRJM-10W均相膜槽压最低,电解12 h后,阴极电流效率为86.25%,阳极电流效率为70.6%,中隔室酸回收率可达73.08%,但阴极液pH增幅最大,中间液Mn^2+浓度最高。     

采用铝阴极从硫酸锰溶液中电沉积金属锰

在MnSO_4-(NH_4)_2SO_4溶液中,以铝板为阴极电沉积金属锰,分别研究电流密度、电解液成分、温度等因素对阴极电流效率、能耗和阴极产物的影响。结果表明:在含Mn~(2+)溶液浓度为30 g/L、(NH_4)_2SO_4浓度为130 g/L、SeO_2浓度为0.04g/L、初始pH值为7.0、电流密度为400 A/m~2、电解温度为35℃时,铝阴极的阴极电流效率为85.8%,能耗为4870.9 kW?h/t,得到的金属锰纯度高于99.5%,晶型为α-Mn。与传统不锈钢阴极(0Cr19Ni9)对比,Mn~(2+)在铝阴极表面的起始沉积电位与在不锈钢阴极表面的相同,但在电沉积初期可以抑制H_2的析出;铝阴极可加速Mn~(2+)的电沉积,增加阴极电流效率,降低直流电耗;同时,铝阴极可以抑制SeO_3~(2-)的还原,减小添加剂SeO_2的消耗量,提高阴极锰的纯度。因此,金属铝具备替代不锈钢作为电沉积金属锰的潜力。     

工艺因素对氨基磺酸盐镀铟阴极电流效率的影响

对氨基磺酸盐体系镀铟阴极电流效率的影响因素及其规律进行了系统的研究,通过分析镀液pH值、电流密度、镀液温度、添加剂以及电镀时间与阴极电流效率的关系,确定了镀铟最佳工艺参数.结果表明:当pH值为1.8～2.0,电流密度为1.8～2.2 A/dm2,温度为20～30 ℃,胺类添加剂加入量少于0.2g/L,电沉积1min,可以获得银白色的铟镀层,且阴极电流效率达到80%以上.     

基于隔膜电积的硫酸铅渣湿法提铅新工艺及电化学机理

根据物料平衡和电荷平衡原理,对Pb(Ⅱ)-Ac~--H~+-H_2O体系进行热力学分析,分析结果表明在接近于实际浸出液的pH值范围内,溶液中PbAc~+平衡浓度最高。以湿法炼锌产出的硫酸铅渣为原料,采用单因素实验法优化"乙酸盐配位浸出-隔膜电积提取铅"的主要工艺条件,采用单因素试验法优化乙酸铅溶液隔膜电积工艺条件,采用线性扫描、循环伏安等电化学测试手段研究Pb(Ⅱ)-Ac~--H_2O体系铅电积过程中阴极电化学行为。结果表明:在反应时间1h、浸出温度70℃、乙酸铵浓度4mol/L、液固比4:1的优化条件下浸出硫酸铅渣,铅浸出率93.28%。在电积温度30℃、Pb~(2+)浓度50 g/L、电流密度100 A/m~2的条件下阴极电流效率98%左右,每吨Pb直流电耗约700 kW·h。在此条件下以硫酸铅渣浸出液直接作为电积液隔膜电积8 h在阴极可以获得纯度99.2%较为致密平整的电铅,阴极电流效率96.16%。铅的还原沉积过程是一个不可逆过程,铅在电沉积初期遵循三维连续成核与颗粒长大机制,升高温度和提高阴极液Pb~(2+)浓度可以促进溶液离子扩散,提高电流效率。     

采用阴离子膜电解法从红土镍矿常压浸出液中制备金属镍

以红土镍矿常压酸浸净化液为原料,采用阴离子交换膜与电解结合的方法制备金属镍。分别研究电解液成分、温度、时间、电流密度和p H等因素对阴极电流效率、回收率、能耗以及槽电压的影响。结果表明:含Ni2+溶液浓度为64 g/L、H3BO4浓度为40 g/L、H2SO4浓度为0.1 mol/L、温度为40℃、电流密度为300 A/m2、p H为5.2时,阴极电流效率达到98.47%,能耗为3470 k W·h/t,得到的金属镍纯度达到99.9%以上,能够满足工业上的要求。     

负压-温度梯度电沉积镍镀层的耐腐蚀性

在负压-温度梯度环境下制备镍镀层,并研究分析不同电沉积工艺条件和参数(如沉积空间气压、阴极面温度、阴极电流密度、添加剂等)对镍镀层在10%HCl溶液和10%H2SO4溶液中的耐腐蚀性的影响。结果表明:无添加剂镀液中制备而成的镍镀层在两种酸性溶液中的腐蚀率均随沉积空间气压(20～5kPa)的降低及阴极面温度(40～65℃)的升高而减小,随阴极电流密度(3～81A/dm2)的增加而增大;相同操作条件下,镀液中加入适量十二烷基硫酸钠添加剂后所得镍镀层的腐蚀率更低。与常态环境(常压、大气环境)下获得的镍镀层相比,负压-温度梯度环境下电沉积的镍镀层的耐腐蚀性增强。     

SnCl_4-HCl体系废电路板元器件的分离及锡的回收

针对现有废旧线路板元器件分离及锡回收工艺所存在环境污染严重、效率低、难以大规模推广应用等问题,采用超声辅助下SnCl_4-HCl体系退除元器件管脚处焊锡,达到废线路板元器件分离的目的;同时,采用隔膜电积技术回收退锡液中的锡并再生出SnCl_4-HCl退锡剂。结果表明:在反应温度50℃、Sn~(4+)浓度30 g/L、盐酸浓度4.0 mol/L、超声频率40 kHz、超声功率100 W的条件下,反应20 min后废线路板元器件管脚及过孔处的焊锡全被退除。以退锡后的液体为电解液,采用隔膜电积技术回收退锡液中的锡;在温度35℃、电流密度200 A/m~2、异极距5 cm、石墨板为阳极、不锈钢板为阴极的条件下进行隔膜电积8 h,阴极得到了平整致密的电积锡,阴极电流效率97.3%,电锡纯度99.9%,阳极电流效率为88.8%,阳极液再生出SnCl_4-HCl溶液,可作为退锡液返回用于超声退锡。     

Nickel electrodeposition from novel citrate bath

A new type of electroplating bath suitable for nickel electrodeposition was developed. Trisodium citrate was used as a complexing agent and a buffer in the bath. The buffering capacity between trisodium citrate and boric acid were compared. The effects were investigated under different conditions of bath composition, current density, pH and temperature on the potentiodynamic cathodic polarization curves, cathodic current efficiency and throwing index, as well as the electrical conductivity of these baths. The optimum conditions for producing sound and satisfactory nickel deposits were： NiSOn6H2O350 g/L, NiCl2·6H2O 45 g/L and Na3C6H5 O7 30 g/L at pH=4 and 55 ℃. The surface morphology of the as-plated Ni deposit was examined by SEM. The results reveal that the nickel deposition obtained from the optimum conditions are composed of compact, non-porous fine grains covering the entire surface. X-ray analysis shows that nickel deposits obtained from the citrate bath have a fine crystal structure compared with deposits from the Watts bath.     

Electrodeposition of Nickel from N,N-dimethylformamide

The electrodeposition of nickel from nickel chloride dissolved in pure N,N-dimethylformamide (DMF) was carried out. The presence of a little hydrochloric acid (specific gravity, 1.18) was essential for electrolysis to occur. Cathode current efficiencies as high as 95%–100% were recorded. A bright deposit with a cathode current efficiency of 97.2% was obtained under operating conditions of pH 4.7, temperature 40 °C and current density 0.5 A dm^-2. An NiCl₂·6H₂O-DMF electrolyte resulted in minimum evolution of hydrogen gas during electrodeposition. X-ray analysis confirmed the deposition of nickel in its purest form with an f.c.c. lattice. A small concentration of Co²⁺ played a vital role in enhancing the cathode current efficiency as well as significantly improving the hardness. Scanning electron micrographs revealed a fine-grained structure void of cracks when the coating was deposited in the presence of an optimum concentration of cobalt chloride.     

Electrochemical studies on the performance of SS316L electrode in electrokinetics

Organic and trace metal pollutants are removed by employing various electrodes in an electrokinetic (EK) process. Stainless steel was used either as an anode or a cathode by various investigators in electroremediation systems. In the present study, the role of SS316L as an anode and cathode in EK system was studied by the measurements of pH, conductivity of electrolyte, and potential of the anode and cathode at different current densities. The weight loss of the anode and cathode and the leaching of chromium, iron, and nickel at different current densities were measured and discussed with an electroosmosis process. The electrochemical behavior of SS316L electrode in neutral, acidic and alkaline pH in soil environment was studied by an electrochemical technique viz. polarization study. Surface analysis of SS316L after EK was done by XPS and SEM. The higher conductivity was noticed at anolyte when compared to catholyte. The weight loss of the anode was in the following order 0.615 > 0.307 > 0.123 mA/cm² and the cathode corrosion rate was vice versa. Peroxide production was also noticed at the anolyte, which may encourage the degradation of the total organic content (TOC) in the soil. The OCP (open circuit potential) of SS316L was about +75 mV vs SCE in the soil extract; while adding acetic acid, the potential shifted to the positive side, to about +380 mV vs SCE. The breakdown potential and the range of passivation potential were higher in acetic acid added system when compared to other systems. Pitting was observed on both the anode and cathode within 48 h during the EK process. The present study concludes that SS is not a proper electrode material for the EK process.     

Composition and Morphologies of Electrodeposited Zinc- nickel-manganese Coatings

A ternary alloy of Zn-Ni-Mn was electrodeposited onto mild steel from a sulphate-citrate bath containing boric and ascorbic acid using both pulse and direct current (DC). The relationships between current density, current efficiency and composition were investigated. Thickness measurements, current efficiency calculations, and compositional analysis using energy dispersive X-ray analysis (EDAX) and SEM characterisation, were undertaken. It was possible to produce an alloy containing up to 10% Ni and 6% Mn. The nickel underwent anomalous co-deposition and the manganese regular co-deposition. Both DC and pulse electrodeposition showed an increase in the Mn and Ni percentage as the applied current density was increased. DC electrodeposition tended to produce higher nickel and manganese contents.     

A Study into the Electrodeposition Mechanisms of Zinc-Nickel Alloys from an Acid-Sulphate Bath

Zinc-nickel alloys were electrodeposited under galvanostatic conditions from a sulphate based electrolyte. The effect of deposition current density on alloy composition was determined for an electrolyte containing 0.58 mol/l nickel and 0.92 mol/l zinc (as sulphates). At current densities exceeding 0.01 A/dm², a transition from normal deposition to anomalous co-deposition (ie where the less noble metal deposits preferentially) was observed and alloys rich in zinc were obtained. The transition current density was observed to increase with an increase in electrolyte temperature or a decrease in electrolyte pH.

The electrodeposition mechanism for zinc-nickel alloys in the transition regions was studied in detail using potentiodynamic cathodic polarisation techniques. The results were consistent with the suppression of nickel deposition due to the precipitation of zinc hydroxide on the cathode surface. This was supported by pH measurements made in the vicinity of the cathode where a rise in pH was detected as the transition current density was approached and exceeded the critical pH for zinc hydroxide precipitation.     

槽边循环电解法回收电镀废水中Ni的研究

对槽边循环电解法回收电镀废水中Ni进行了分阶段实验研究,包括小型试验、扩大试验以及系统扩大试验。试验结果表明,适合工业生产中使用的操作条件如下：Ni离子浓度可在0．5～2．5/L变化,电流密度40～80A／m^2,槽电压3—6V,pH=4．5～5．5;当Ni离子浓度保持在1．0～2．5g／L,若连续操作电流密度采用100～150A／^2,则电流效率仍大于40％;若从高浓度操作到低浓度,每次回收到0．5/L,电流密度应取40～80A／^2,操作10次后,可回收到使浓度小于0．1g／L,弃掉,则回收槽的回收率大于99％;由3类不同规模试验的对比中可以看出,在相同条件下,电流效率几乎相等。研究表明,采用槽边循环电解法回收电镀废水中的Ni是完全可行的,且可保证较高回收效率。     

Chlorine inclusion mechanism in high purity copper electrorefining from nitric acid system

A practical approach was introduced to study the inclusion mechanism of chlorine in high purity copper electrorefining from nitric acid system via cyclic voltammetry (CV) combined with electrodeposition experiments. The CV curves display an obvious reduction peak of CuCl intermediate, which can provide an insight into the electrochemical behavior of this inclusion. Experimental results show that the increase of HNO₃ concentration is favorable to reducing the quantity of chlorine inclusion although there is a slight decline in cathodic current efficiency. The optimum conditions for copper electrorefining in nitric acid system are HNO₃ concentration in solution of 1−2 mol/L, moderate temperature of ~35 °C with current density not exceeding 25 mA/cm². Based on the theoretical studies, an optimized copper electrorefining experiment was designed to simulate the industrial electrolysis, by which high purity copper can be obtained with chlorine inclusion less than 10 μg/g and current efficiency higher than 90%.     

氯盐体系锡隔膜电沉积仿真模拟

采用COMSOL多场耦合计算机仿真软件对氯盐体系锡隔膜电沉积进行了仿真模拟,研究锡隔膜电积时电解槽内离子浓度、流体密度、流体速度、电流密度等的分布特征及其随时间的变化规律。结果表明:锡隔膜电积时槽内离子浓度分布受到入口流速、电流密度、电积时间、槽内离子互相作用的影响而发生变化。增加进液速度及降低HCl浓度有利于提高电解液平均密度及阴极表面Sn^2+的最低浓度。电积时极板边缘发生离子对流,顶部对流速度高于边缘处对流速度,且流体密度梯度影响离子对流方式。极板周围电流密度分布呈非均匀分布,在电极边缘发生电流偏转。增加电流密度能降低阴极表面Sn^2+最低浓度及流体的平均密度,同时也将增加阴极表面流体的平均流速,并使得阴极产物厚度不均匀。     

氨络合物体系中杂质Zn~(2+)对电沉积镍的影响

通过霍尔槽试验研究氨络合物体系中杂质Zn~(2+)对镍电沉积的影响,采用电化学工作站测试不同Zn~(2+)浓度时的循环伏安曲线、稳态极化曲线及电流时间暂态曲线.结果表明:杂质Zn~(2+)的含量为0.1 g/L时,在小于2.78 A/dm的电流密度范围内可正常沉积出金属镍;杂质Zn~(2+)含量大于0.5 g/L时,在较大的电流密度范围内均无法正常沉积出金属镍;过电位小于640 mV时,Zn~(2+)的存在不影响阴极反应的传递系数,且不改变阴极反应机理;当过电位大于640 mV,且杂质Zn~(2+)的浓度大于0.5 g/L时,阴极反应的传递系数减小,阴极反应机理发生改变;杂质Zn~(2+)浓度大于0.5 g/L时,严重影响镍电结晶过程的成核速率,这是其抑制金属镍电沉积的主要原因.因此,采用镍氨络合物体系电积金属镍,应控制杂质Zn~(2+)的含量小于0.1 g/L.