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Journal of Electrochemistry ›› 2017, Vol. 23 ›› Issue (6): 702-707.doi: 10.13208/j.electrochem.161129

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Effect of Fe2+/Fe3+Interconvertion on Reduction Behavior of Fe3+ in Acidic Electrolytes

QIN Jian-xin*, LIN Feng, LIU Wen-ping, CHEN Chao, REN Meng-de   

  1. Guangxi Key Laboratory of super-hard material, National Special Mineral Materials Engineering Technology Research Center, China Nonferrous Metals (Guilin) Geology and Mining Co., Ltd. Guilin 541004, China
  • Received:2016-11-29 Revised:2017-03-03 Online:2017-12-28 Published:2017-03-30
  • Contact: QIN Jianxin E-mail:qdqinjianxin@163.com

Abstract: 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=0.35V 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.

Key words: Fe2+/Fe3+ interconvertion, cyclic voltammetry, polarization curve, reduction behavior

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