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Table 1 Summary of green rust chemical compositions and associated Fe2+ concentrations

From: Effects of metal cation substitution on hexavalent chromium reduction by green rust

Reactant

Expected chemical compositiona

[Fe2+](aq) (mmol L−1)b

GR-SO4

\(Fe_{4}^{II} Fe_{2}^{III} \left( {OH} \right)_{12} SO_{4} \cdot2H_{2} O\)

25

Al-GR

\(Fe_{4}^{II} Fe_{1.9}^{III} Al_{0.1} \left( {OH} \right)_{12} SO_{4} \cdot2H_{2} O\)

27

Mg-GR

\(Fe_{3.8}^{II} Mg_{0.2} Fe_{2}^{III} \left( {OH} \right)_{12} SO_{4} \cdot2H_{2} O\)

23

Zn-GR

\(Fe_{3.8}^{II} Zn_{0.2} Fe_{2}^{III} \left( {OH} \right)_{12} SO_{4} \cdot2H_{2} O\)

23

  1. aBased on ratio of cations in solution prior to titration
  2. bExpected [Fe2+](aq) is 20–25 mmol L−1