物理化学学报 >> 2001, Vol. 17 >> Issue (12): 1067-1071.doi: 10.3866/PKU.WHXB20011203

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铂电极上醋酸-醋酐溶液中Mn(III)/Mn(II)电对研究

潘湛昌;陈启元;黄慧民   

  1. 中南大学化学化工学院，长沙　410631；广东工业大学轻工化工学院，广州　510090
  • 收稿日期:2001-04-04 修回日期:2001-07-26 发布日期:2001-12-15
  • 通讯作者: 潘湛昌 E-mail:wlhx@gdut.edu.cn

Studies of Mn(III)/Mn(II) on Platinum Electrode in Acetic Acid-Anhydride Solution

Pan Zhan-Chang;Chen Qi-Yuan;Huang Hui-Min   

  1. College of Chemistry and Chemical Engineering, Central South University, Changsha　410083；Faculty of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou　510090
  • Received:2001-04-04 Revised:2001-07-26 Published:2001-12-15
  • Contact: Pan Zhan-Chang E-mail:wlhx@gdut.edu.cn

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摘要： 平衡电极电势实验确定了25 ℃， 1.5 mol•L－1醋酸钾＋醋酸-醋酐(3:1体积比)溶液中Mn(III)/Mn(II)的条件电极电势为0.719 V（vs SCE）;采用电势扫描和旋转圆盘电极技术研究了醋酸-醋酐溶液中铂电极上Mn(III)/Mn(II)电对的阳极氧化动力学. 结果表明:Mn(II)阳极氧化成Mn(III)的电极反应控制步骤属电荷传递过程, 阳极传递系数β=0.347,交换电流密度i0=5.84×10－6 A•cm－2，阳极标准反应速率常数ka=1.35×10－8 m•s－1, Mn(II)和OAc－的反应级数均为一级.

关键词: Mn(III)/Mn(II), 醋酸, 条件电极电势, 阳极氧化, 电荷传递动力学参数

Abstract: The electrochemical behavior of Mn(III)/Mn(II) on platinum electrode in acetic acid-anhydride was investigated. The results show that the conditional electrode potential of Mn(III)/Mn(II) was 0.719 V(vs SCE) in the solution of 1.5 mol•L－1 KOAc＋HOAc-Ac2O(3:1 volume ratio) at 25 ℃. The results of potential sweep and RDE on platinum electrode show that the rate determing step of the electrode processes for Mn(II) anodic oxidation was a charge-transfer step. The anodic charge-transfer kinetic parameters were determined. The results show that the anodic charge-transfer coefficient is 0.347, the exchange current density i0 is 5.84×10－6 A•cm－2, the conditional charge-transfer rate constant ka is 1.35×10－8 m•s－1 at 25 ℃. The rate was found to be first order with respect to the concentration of both Mn(II) and OAc－.

Key words: Mn(III)/Mn(II), Acetic acid, Conditional electrode potential, Anodic oxidation, Change-transfer kinetic parameters