Evidence for Fenton Photoassisted Processes Mediated by Encapsulated Fe ions at Biocompatible pH Values

Iron alginate gel beads were prepared starting from sodium alginate solutions. Fe complexed with carboxylate is active during the Fenton-enhanced decoloration/degradation of Orange II via the encapsulated Fe catalyst. By energy-dispersive X-ray microanalysis (EDX) it was shown that a significant amount of Fe was on the catalyst surface and only a smaller fraction inside the cross-linked Fe alginate. The Fe alginate beads were ∼2 mm in diameter containing highly dispersed Fe species with sizes of about 0.5 nm. The Fe alginate mediated decoloration of Orange II takes place in less than an hour in the presence of H 2 O 2 under visible light irradiation, at pH values between 5 and 8. Repetitive decoloration of Orange II solutions was observed by addition of the azo dye at the beginning of each cycle.