酸性溶液中Fe^(2+)/Fe^(3+)相互转换对电极还原行为的影响  

Effect of Fe^(2+)/Fe^(3+) Interconvertion on Reduction Behavior of Fe^(3+) in Acidic Electrolytes

作　　者：秦建新[1] 林峰[1] 刘文平[1] 陈超[1] 任孟德[1] 

机构地区：[1]中国有色桂林矿产地质研究院国家特种矿物材料工程技术研究中心广西超硬材料重点实验室,广西桂林541004

出　　处：《电化学》2017年第6期702-707,共6页Journal of Electrochemistry

基　　金：广西科技计划基地和人才专项(重点实验室建设项目;No.16-380-35)资助

摘　　要：采用线性扫描伏安法和循环伏安法研究了含有Cl^-、SO_4^(2-)的酸性溶液中Fe^(2+)/Fe^(3+)相互转换对电极反应和Fe^(3+)还原过程的影响.结果表明,[Fe]T=1 mol·L^(-1)条件下,溶液中Fe^(3+)/Fe^(2+)的还原析出过程经过两个阶段:1)E=0.35 V左右Fe^(3+)还原成Fe^(2+)过程;2)E=-0.3 V之后H+的还原,同时Fe^(2+)离子与OH-相结合生产Fe(OH)_2;Fe^(3+)/Fe^(2+)的相互转化主要影响Fe^(3+)的第一还原阶段的还原峰电流和峰电位.|ipa/ipc|值随c(Fe^(3+))/c(Fe^(2+))的增大而增大,且扫描速率慢时影响大,扫描速率快时影响小;0.50 mol·L-1Fe^(2+)+0.50 mol·L-1Fe^(3+)时,随扫描速率的变化|ipa/ipc|值变化最小(|ipa/ipc|≈1.20).同时,c(Fe^(3+))/c(Fe^(2+))也影响着平衡电位,平衡电位随c(Fe^(3+))/c(Fe^(2+))增大而正移,电位从E1=0.501 V升至E5=0.565 V.The influences of ferrous/ferric（Fe2＋/Fe3＋） interconvertion on electrochemical reduction and electrode reaction of Fe3＋were investigated by using linear sweep voltammetry,potentiostatic method and cyclic voltammetry（CV） in acidic electrolytes containing chloride ion（Cl-） and sulfate ion（SO42-）.It was shown that the reduction process of Fe3＋/Fe2＋would take place in two independent stages：1） the reduction of Fe3＋ to Fe2＋at E=0.35 V and 2） the co-precipitation of Fe2＋by forming Fe（OH）2（E ≤-0.3 V）instead of Fe.The major effect of Fe2＋/Fe3＋interconvertion on the reduction is the ｜ipa/ipc｜ of quasi-reversible and equilibrium potential in the first stage.Practically speaking,the ｜ipa/ipc｜ values increased with the increase of c（Fe3＋）/c（Fe2＋）,and the values of ｜ipa/ipc｜ at fast sweep rates were less strongly affected than those at slow sweep rates.The least variation in ｜ipa/ipc｜（｜ipa/ipc｜≈1.20） with sweep rate was observed in 0.50 mol·L-1 Fe2＋ and 0.50 mol·L-1 Fe3＋solutions.Meanwhile,the equilibrium potential was also affected by c（Fe3＋）/c（Fe2＋）.The equilibrium potential shifted more positively from E1= 0.501 V in No.1 to E5=0.565 V in No.5 among the five samples studied in this work.

关 键 词：Fe2+/Fe3+相互转换 循环伏安 极化曲线 还原行为 

分 类 号：O646.5[理学—物理化学]