21 research outputs found
Zinc Dioxide Nanoparticulates: A Hydrogen Peroxide Source at Moderate pH
Solid peroxides are a convenient
source of hydrogen peroxide, which
once released can be readily converted to active oxygen species or
to dissolved dioxygen. A zinc peroxide nanodispersion was synthesized
and characterized, and its solubility was determined as a function
of pH and temperature. We show that zinc peroxide is much more stable
in aqueous solutions compared to calcium and magnesium peroxides and
that it retains its peroxide content down to pH 6. At low pH conditions
H<sub>2</sub>O<sub>2</sub> release is thermodynamically controlled
and its dissolution product, Zn<sup>2+</sup>, is highly soluble, and
thus, hydrogen peroxide release can be highly predictable. The Gibbs
free energy of formation of zinc peroxide was found to be −242.0
± 0.4 kJ/mol and the enthalpy of formation was −292.1
± 0.7 kJ/mol, substantially higher than theoretically predicted
before. The biocidal activity of zinc peroxide was determined by inactivation
studies with Escherichia coli cultures,
and the activity trend agrees well with the thermodynamic predictions