Effect of rhodamine B degradation during the formation of lepidocrocite

• Adsorption and degradation of RhB during lepidocrocite formation were analyzed.
• Adsorption and degradation of RhB were affected by the action of system itself.
• Comprehensive effect occurred in the degradation of RhB during the reaction.

This paper described the adsorption and degradation of rhodamine B (RhB) during lepidocrocite (γ-FeOOH) formation by air oxidation of Fe(OH)2 under visible-light irradiation in the presence of trace ethylenediaminetetracetic acid (EDTA). The results showed that RhB could be adsorbed on a green rust II (GR II) intermediate and on the γ-FeOOH product surface during γ-FeOOH formation and be degraded via heterogeneous and homogeneous photo-Fenton-like reactions. Fe2+ and H2O2 coexisted in the reaction system, and Fe2+ or H2O2 both promoted the adsorption and degradation of RhB. As the reaction proceeded, the increase in acidity enhanced the efficiency of the photo-Fenton-like reactions, which led to an increase in RhB degradation. The adsorbed RhB exhibited desorption behaviors because of the transformation of GR II and growth of γ-FeOOH. A possible mechanism was suggested for the comprehensive effect of RhB degradation during the reaction.

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