Attempting to use more than two coatings did not improve the rate of QAY degradation and simply led to more loose P25 removal from the surface during the 24 h agitation period.
Both the Degussa P25 and the QAY are nontoxic, non-flammable and non-corrosive and pose only a minor risk of respiratory irritation when handled in solid form.
QAY degradation exhibits Langmuir-Hinshelwood (LH) kinetics at concentrations between 2 [[micro]meter] and 30 [[micro]meter].
Our experimental results show that a reasonable exposure time (20 minutes), at 30 [degrees] C with a 9W UV-A source and a cylindrical vessel (volume 350 mL, ID 7 cm) is required to degrade QAY to 50% of its original concentration.
The rate of QAY degradation increases with temperature according to the Arrhenius equation:
Adding a 0.35% by weight hydrogen peroxide solution increased the QAY degradation rate by between 15 to 25 percent over that found without hydrogen peroxide.