氢氧化钠水溶液体系中金属铬的电化学氧化过程  

Electrochemical Oxidation of Metal Chromium in Sodium Hydroxide Aqueous Solution

作　　者：韩平 冯海涛[1,2] 董亚萍 田森[1,2,3] 张波 李武 HAN Ping;FENG Hai-tao;DONG Ya-ping;TIAN Sen;ZHANG Bo;LI Wu(Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources,Qinghai Institute of Salt Lakes,Chinese Academy of Sciences,Xining 810008,Chinas;Qinghai Engineering and Technology Research Center of Salt Lake Resources Development,Xining 810008,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院青海盐湖研究所,中国科学院盐湖资源综合高效利用重点实验室,西宁810008 [2]青海省盐湖资源开发工程技术研究中心,西宁810008 [3]中国科学院大学,北京100049

出　　处：《电化学》2020年第3期413-421,共9页Journal of Electrochemistry

基　　金：青海省科技厅基础研究项目(No.2017-ZJ-786);青海省重大科技专项(No.2016-GX-A10)资助。

摘　　要：铬铁电氧化溶出技术是一种全新的制备铬酸钠的方法,具有反应条件温和、过程可控、工艺环保等优点,然而金属铬在NaOH水溶液中的电化学氧化过程尚不明确.本文采用循环伏安法(CV)和阳极极化法(LSV)对金属铬在NaOH水溶液中的电化学氧化过程进行研究.使用EDS、SEM、XRD和XPS对电解前后的金属铬表征,判断中间物的产生,使用紫外可见分光光度计验证电解液中生成了铬酸钠.结果表明,金属铬和中间产物Cr(OH)3可能依次发生电化学氧化直接生成Na2CrO4,阳极极化为金属铬的活化.随着NaOH溶液浓度的增加,Cr(OH)3和Na2CrO4的生成量在增加,金属铬电化学氧化制备铬酸钠的适宜条件为碱浓度≥2 mol·L^-1,阳极电势≥1.6 V(vs.SCE).Ferrochrome electrolysis technology is a novel method for preparing sodium chromate(Na2CrO4). Although the method performs well at soft reaction conditions, controllable process, environmentally friendly production process, etc., the electrochemical oxidation process of metal chromium in NaOH aqueous electrolyte is still unclear. At present, there are few research articles about specific electrochemical oxidation of metal chromium in NaOH aqueous electrolyte. It is, therefore, meaningful to carry out the research in electrochemical oxidation mechanism of chromium. The electrochemical oxidation of metal chromium in 0.01 mol·L^-1- 10 mol·L^-1 NaOH aqueous electrolytes at 20 ℃ was studied by cyclic voltammetry(CV, Scan rate: 100 m V·s^-1) and linear sweep voltammetry(LSV, Scan rate: 1 m V·s^-1) through controlling the potential range. The working electrode(WE) was a chromium rod,the counter electrode(CE) was a platinum sheet, and the reference electrode(RE) was a saturated calomel electrode(SCE). EDS,SEM, XRD and XPS were used to characterize the metal chromium before and after the electrolysis to determine intermediate during electrochemical oxidation. Ultraviolet-visible(UV) spectrophotometer was used to analyze the electrolyte solution after the electrolysis to confirm the formation of Na2CrO4. The results indicated that Cr(0) and Cr(OH)3 might undergo electrochemical oxidations in sequence to directly form Na2CrO4. When the anode potential was negative, chromium generated Cr(OH)3 film through electrochemical oxidation, while hydroxide ions(OH-) underwent electrochemical oxidation to form oxygen. On the othere hand,when the anode potential was positive, two electrochemical reactions:(1) Cr(0) → Cr(Ⅵ);(2) Cr(OH)3→ Cr(Ⅵ) took place. Thus,the anodic polarization included activation of Cr(0). The dissolution reaction of chromium was stimulated by OH-at a higher concentration of NaOH aqueous solution. Futhremore, the amounts of Cr(OH)3 and Na2CrO4 formed were increased with the increased concentration of

关 键 词：金属铬 NAOH水溶液 电化学氧化 循环伏安 阳极极化 

分 类 号：O646[理学—物理化学] TQ151[理学—化学]