Electrochemical investigations of copper behaviour in different cupric complex solutions: Voltammetric study

The electrochemical behaviour of copper has been investigated in different cupric complex solutions by cyclic voltammetry. In pyridinic and picolinic solutions the reduction of cupric complex occurred in two stages leading to Cu(I) and Cu(0), respectively. The electrodeposited copper is oxidized in two steps leading to Cu(I) and Cu(II) as in ammoniacal cupric complex solutions. In glycine, alanine, sulfamic acid and ethylenediamine solutions, the cuprous complex is an intermediate in the cupric complex reduction but it is not detected during the oxidation of the electrodeposited copper in these solutions. In EDTA and triethanolamine solutions, the cuprous complex is not observed. The rate of copper etching was determined in pyridinic and ammoniacal cupric solutions and was shown to be faster in ammoniacal cupric solutions than in the pyridinic solutions.     

Influence of ammonium salt on electrowinning of copper from ammoniacal alkaline solutions

In order to develop an energy-saving copper recycling process from wastes, electrochemical measurements were conducted in ammoniacal alkaline solutions containing Cu(I) ions and an ammonium salt of sulfate, chloride or nitrate. The results of each system were then compared. The polarization measurements suggested that the voltage required for the electrode process is lower in the chloride and nitrate systems than that in the sulfate system. The cathode current efficiency during the copper electrodeposition varied from 39 to 97% and increased with current density in the chloride and sulfate systems. In the nitrate system, the lowest cathode current efficiency of 30% was observed because of nitrate ion reduction. Based on these results, the power consumption required for the electrowinning stage of the copper recycling process was calculated. Among these three systems, the chloride system showed the lowest power consumption of 500 kWh t⁻¹ at the current density of 200 A m⁻², which is about 25% of the conventional copper electrowinning process from a copper sulfate-sulfuric acid solution.     

电泳涂装的漆膜缺陷及其防治

介绍了汽车涂装工艺电泳过程中出现的一些常见缺陷，对这些缺陷产生的原因进行分析并阐述其防治方法。     

Hydrogen evolution in alkaline solution on electrolytic nickel-cobalt and nickel-iron deposited with different bath compositions and current densities

Nickel-cobalt and nickel-iron electrodeposits were characterized as hydrogen electrodes in alkaline water electrolysis (6 mol/L KOH, 25°C). The nickel-based codeposits were fabricated with different bath compositions and at different current densities. The hydrogen evolution in water electrolysis on the nickel-based codeposits was apparently enhanced as compared with that on nickel. The improvement of the electrocatalytic behaviour of the hydrogen electrodes is attributed to their composition and an increase of their active surface, which are dependent on the electrodeposition conditions.     

Effect of dopants on the performance of CuO–CeO2 catalysts in methanol steam reforming

Steam reforming of methanol was carried out over a series of doped CuO–CeO₂ catalysts prepared via the urea–nitrate combustion method. XRD analysis showed that at least part of the dopant cations enter the ceria lattice. The addition of various metal oxide dopants in the catalyst composition affected in a different way the catalytic performance towards H₂ production. Small amounts of oxides of Sm and Zn improved the performance of CuO–CeO₂, while further addition of these oxides caused a decrease in catalyst activity. XPS analysis of Zn- and Sm-doped catalysts showed that increase of dopant loading leads to surface segregation of the dopant and decrease of copper oxide dispersion. The addition of oxides of La, Zr, Mg, Gd, Y or Ca lowered or had no effect on catalytic activity, but led to less CO in the reaction products. Noble-metal modified catalysts had slightly higher activity, but the CO selectivity was also significantly higher.     

电沉积Ni—W—P活性阴极的制备研究

研究了电沉积Ni—W—P电极的析氢电催化活性、长期稳定性,并对其催化活性进行了分析。此电极具有优良的析氢电催化活性和长期电解稳定性,是制作活性阴极的材料之一。     

Electrodeposition of silver from nitrate solution: Part II. Mechanism of the effect of phosphate ions

The mechanism of compact Ag-film formation by electrolysis from nitrate solution with addition of small amounts of phosphate ions is elucidated. It is shown that the phosphate ions exert their effect by lowering the exchange current density. Consequently, the radii of nucleation exclusion zones also diminishes, thus producing conditions stimulating electrodeposition of continuous thin Ag-film.     

Polyaniline for corrosion prevention of mild steel coupled with copper

Polyaniline emeraldine base/epoxy resin (EB/ER) coating was investigated for corrosion protection of mild steel coupled with copper in 3.5% NaCl solution. EB/ER coating with 5-10 wt% EB had long-term corrosion resistance on both uncoupled steel and copper due to the passivation effect of EB on the metal surfaces. During the 150 immersion days, the impedance at 0.1 Hz for the coating increased in the first 1-40 days and subsequently remained constant above 10⁹ Ω cm², whereas that for pure ER coating fell below 10⁶ Ω cm² after only 30 or 40 days. Immersion tests on coated steel-copper galvanic couple showed that EB/ER coating offered 100 times more protection than ER coating against steel dissolution and coating delamination on copper, which was mainly attributed to the passive metal oxide films formed by EB blocking both the anodic and cathodic reactions. Salt spray tests showed that 100 μm EB/ER coating protected steel-copper couple for at least 2000 h.     

纤维微粒在电解液中运动方式的模拟

采用Fluent软件提供的离散相模型,重点研究了柱状纤维粒子在电解液流场中的运动情况,分析了溶液参数,如粘度、密度、旋转转速以及颗粒性质对其运动状态的影响.在模拟实验中,建立了磁力搅拌子和板状搅拌子两种搅拌模型.模拟结果表明:溶液粘度为0.2 kg/(m·s)左右,搅拌转速在20～30 rad/s范围内,板状搅拌子模型能够产生稳定的流场.粒子在垂直于搅拌子的平面内基本上作圆周运动,确保在复合电镀过程中,晶须(纤维粒子)将最大程度上以定向的方式被包覆在镀层中.     

[Cu_2(Gly—GlyO)_2(OH)_2(4,4—bpy)]·9H_2O配合物合成、晶体结构研究

采用Gly—GlyOH,4,4＇—联吡啶与Cu(NO_3)_2·H_2O在二次水溶液中反应,合成出以4,4＇—bpy为中继基,Gly—Glyo为螯环新型双核铜配合物。经X射线单晶结构分析确定该配合物品体的化学结构式:[(H_2NCH_2CONHCH_2COO) Cu(OH) (C_(10)H_8N_2)Cu(OH) (H_2NCH_2CONHCH_2COO)]·9H_2O.晶体属于三斜晶系,P_空间群,晶胞参数a=1.1412nm,b=1.2298nm,C=1.4269nm,α=113.82°,β=101.91°,y=103.64°,V=1.6747nm~3,Z=2。衍射数据是在Nicolet XRD R3型四圆衍射仪上收集,结构参数经块矩阵最小二乘法精修后,最终一致性因子R值为0.068,RW值为0.057。