pH below optimum

Reference

pH above optimum

Reference

Scavenging of ^ŸOH by excess H⁺

[88]

Deficiency of H⁺, which hampers ^ŸOH formation

[59]

Formation of [Fe(H₂O)]²⁺ which has low oxidative power

[89]

Decomposition of H₂O₂

[90]

Prevent the interaction between Fe³⁺ and H₂O₂

[91]

Decline in the oxidative power of ^ŸOH

[92]

H₂O₂ may be unstable to formed ${\text{H}}_{\text{3}}{\text{O}}_{\text{2}}^{\text{+}}$ which impedes production of ^ŸOH

[93]

Precipitation of Fe³⁺ as iron hydroxide

[60] [61]