The Effect of Electronic and Optical Properties on the Kinetic Photocatalytic Model of Methyl Blue Degradation

The photocatalytic activity as a function of effective irradiance, photocatalytic quantum yield and reactant coverage was thoroughly assessed for the proper photoreactor (PhR) selection. The emitted wavelength and effective irradiance of several PhRs, equipped with fluorescent and light-emitting diode (LED) lamps, were tested in the photodegradation of methylene blue (MB) in the solid phase using an AgTiO₂ photocatalyst. Among all tested PhRs, the one equipped with the low-pressure Hg lamp enhanced the photodegradation of MB, as the Hg lamp emitted UV-type radiation, which promotes the simultaneous photoactivation of the TiO₂ and the surface plasmon resonance phenomenon of the Ag nanoparticles. It was determined that high values of effective irradiance promoted photocatalytic activity because of the greater amount of photogenerated species [e^-/h⁺]. Also, it was determined that the effective irradiance used in the photocatalytic process slows down the recombination rate of the [e^-/h⁺] into photocatalytic material. A kinetic photocatalytic model (KPM) was proposed to describe photocatalytic reactions as a function of effective irradiance, photocatalytic quantum yield and reactant coverage, considering photocatalytic pseudo-steady state according to the reactant equilibrium coverage (Langmuir isotherm) and the transfer processes of the photoinduced charge carrier species.