Reactivity of anatase and rutile titanium dioxide powder with hydrogen peroxide vapour: Implication for reactive coating systems for laundry enzymes

Abstract

The reactivity of solid particles of two forms of TiO2, rutile and anatase, with H2O2 vapour was investigated for use as reactive coatings protecting granular formulations of enzymes. Reactivity tests using potassium titanium oxide oxalate as a competition probe showed a high reactivity of anatase at both high and low H2O2 pressure, whereas rutile was moderately reactive only at high H2O2 pressure. Heating H2O2-treated rutile and anatase led to release of oxygen, but not of surface-bound H2O2. For rutile, electron spin resonance measurements showed formation of radical intermediates. Anatase showed a mechanism comprising reversible binding of H2O2 and catalytic cleavage of H2O2 without formation of radicals. Anatase-coated detergent enzyme granules confirmed the protection against H2O2 vapour. Overall, this work shows the potential of anatase as a reactive coating material in laundry granules as an alternative to the current formulation.