Activation of H2O2 and superoxide production using a novel cobalt complex based on a polyampholyte

Abstract

A new catalyst based on Co(II) and a hydrogel with property of polyampholyte was characterized by equilibrium studies of Co(II) uptake, solid-state NMR and energy dispersive X-ray analysis. The matrix derived from methacrylic acid and 2-methylimidazole is easily synthesized in one-spot strategy, and combines coordination properties with chemical resistance. The catalytic activity of this material on H2O2 activation was studied by electron spin resonance, which confirmed the release of superoxide radical. A possible mechanism of interaction involves the simultaneous production of dioxygen, protons and water. The catalytic performance was assessed in the activation of H2O2 for the oxidation of two representative organic compounds of environmental concern. About 70% of methyl orange, a model azo dye, was removed from distilled water in 2 h by oxidation with H2O2 60 mM and by adsorption on the catalyst. The amount of adsorbed dye was minimized in the presence of 0.1 M Na2SO4. The kinetics of the processes followed a pseudo-first-order empirical model, and the catalyst was recovered and re-used. Epinephrine was chosen as a pharmaceutical model susceptible to superoxide attack. About 80% of conversion to adrenochrome was reached in less than 6 min, following a pseudo-first-order kinetic model.