• journal_title：Clays and Clay Minerals
• Contributor：Liang Tao ; Fangbai Li ; Yongkui Wang ; Kewen Sun
• Publisher：Clay Minerals Society
• Date：2010-
• Format：text/html
• Language：en
• Identifier：10.1346/CCMN.2010.0580507
• journal_abbrev：Clays and Clay Minerals
• issn：0009-8604
• volume：58
• issue：5
• firstpage：682
• section：Articles

Much attention has been paid to the adsorption of Fe(II) onto mineral surfaces as it is a crucial step in enhancing the reductive activity of Fe(II) species. The present study elucidates the role of Fe(II) adsorbed on Fe (oxyhydr)oxides (γ-FeOOH, α-FeOOH, and α-Fe₂O₃) for the reductive transformation of 2-nitrophenol (2-NP), using cyclic voltammetry (CV). Studies of Fe(II) adsorption and 2-NP reduction kinetics showed that an increase in pH gave rise to an elevated density of adsorbed Fe(II) on mineral surfaces, which further resulted in an enhanced reaction rate of 2-NP reduction. In addition, CV tests showed that the enhanced activity of Fe(II) species is attributed to the negative shift of peak oxidation potential (E_P) of the Fe(III)/Fe(II) couple. The dependence of adsorbed Fe(II) reactivity on pH values was proven by the three linear correlations obtained (ln k vs. pH, E_P vs. pH, and ln k vs. E_P). The present study demonstrated that the reductive activity of adsorbed Fe(II) species can be indicated by the E_P value of active Fe(II) species. Moreover, the electrochemical approach can be used as an effective tool to study the reductive activity of adsorbed Fe(II) species in subsurface environments.