Evaluation of hematin catalyzed Orange II degradation as a potential alternative to horseradish peroxidase

AGOSTINA CORDOBA; IVANA MAGARIO; MARIA LUJAN FERREIRA

INTERNATIONAL BIODETERIORATION & BIODEGRADATION

ELSEVIER SCI LTD

Lugar: Suitland; Año: 2012 p. 60 - 72

0964-8305

The catalytic performance of hematin was evaluated for the decolorization of solutions of the monoazoic textile dye Orange II in comparison to horseradish peroxidase (HRP) by means of response surface methodology. Conversions were mostly affected by medium pH followed by catalyst and peroxide concentration whereas temperature impact was negligible. Both catalysts removed more than 92 % colour from 75 mg l-1 solutions after 60 min. The optima for catalytic performances were identified at alkaline conditions and low peroxide to dye molar ratio (2.5 for HRP and 5 for hematin). Conversion results suggest existence of a catalatic route for activity recuperation and a lower sensitivity of hematin to peroxide and organic radical attack. Chemical oxygen demand values revealed lack of mineralization after treatment. UV/visible and FTIR spectra of treated solutions confirmed azo bond breaking and presence of oxygenated aliphatic hydrocarbon moieties as main products with both catalysts whereas in case of HRP coupling products are also produced after 24 h. These results are presented for the first time for hematin as biomimetic of peroxidase for dye degradation with a systematic study of variables using the Doehlert array. As a result, hematin emerges as an effective alternative to HRP for azo-dyes removal.