Photodissolution of iron oxides in malonic acid

Abstract

The influence of 254-nm irradiation on the dissolution rate of magnetite (Fe 3 O 4 ) and maghemite (γ-Fe 2 O 3 ) suspended in aqueous solutions of malonic acid is analyzed and compared with the dark reaction. The effect of the addition of Fe 3+ , reductants such as ascorbic acid and oxidants such as Ag + or O 2 is described. Photochemical initiation involves the production of >Fe II by electrons photogenerated on the oxide, which triggers thermal dissolution. Experimental results are fitted by analytical and numerical solutions of the set of kinetic equations. The calculated fitting parameters reflect the lower activity of iron oxides in malonic acid compared to EDTA media.