论文部分内容阅读
在725℃温度下,对MgCl2-KCl-NaCl-CaCl2熔盐体系进行电解。研究结果表明,镁电解过程中阴极过电压ηc只有12~51 mV,电解过程的过电压主要是由阳极引起的;阴极还原过程的极限扩散电流密度id为1.56 A/cm2;镁离子阴极放电反应的电子转移数为1.98;2个电子转移步骤之前存在着前置转化步骤MgCl+Mg2++C1-。应用循环伏安法对4种不同配比下的镁离子行为进行的研究结果表明,CaCl2质量分数从10%增加到40%,维持MgCl2质量分数为10%以及NaCl与KCl的质量比为6∶1不变,随着CaCl2质量分数的增加,镁离子结合成不易移动的络合阴离子,镁离子迁移的电流分数减小,镁离子的析出电位从-1.595 V逐渐负移至与钙、钠共同沉积,阴极峰值电流Ipc值逐渐增大,阳极峰值电位与阴极峰值电位之差的绝对值|φpa-φpc|逐渐增大,阴极放电反应的可逆性逐渐降低。
The molten salt system MgCl2-KCl-NaCl-CaCl2 was electrolyzed at 725 ℃. The results show that the cathode overvoltage ηc is only 12 ~ 51 mV in the process of magnesium electrolysis, and the overvoltage in the electrolysis process is mainly caused by the anode; the limit diffusion current density id of the cathode reduction process is 1.56 A / cm2; The number of electron transfer was 1.98. Preceding conversion step MgCl + Mg2 ++ C1- existed before the two electron transfer steps. The results of cyclic voltammetry on the behavior of magnesium ions in four different ratios show that the mass fraction of CaCl2 is increased from 10% to 40%, the mass fraction of MgCl2 is 10% and the mass ratio of NaCl to KCl is 6: 1, with the increase of CaCl2 mass fraction, the magnesium ions combine to form non-moving complex anions, the current fraction of magnesium ions decreases, and the precipitation potential of magnesium ions gradually shifts from -1.595 V to that of calcium and sodium The cathodic peak current Ipc gradually increased, and the absolute value of the difference between the anodic peak potential and the cathodic peak potential | φpa-φpc | increased gradually. The reversibility of cathodic discharge reaction gradually decreased.