Assessment of an intrinsic kinetic model for TiO2–formic acid photodegradation using LEDs as a radiation source

Abstract

Dependency of HCOOH photodegradation on radiation wavelength was evaluated by using LEDs with different emission spectra. Two commercial TiO₂ photocatalysts, one of them modified with carbon, were used. From the optical properties of the photocatalyst suspensions, higher scattering coefficients were detected for the C modified TiO₂. Radiation absorption profiles and volumetric rates of photon absorption were calculated to analyze the effect of radiation wavelength, photocatalyst loading and the amount of incident radiation flux. A 365 nm LED provided faster photodegradation rates and quantum efficiencies and consumed less electric power. Furthermore, when an LED with an emission peak centered at 405 nm was employed, the photocatalyst modified with carbon yielded faster photodegradation rates than the photocatalyst only made of TiO₂. Finally, an intrinsic kinetic model was developed to simulate the process and the intrinsic kinetic parameters were obtained for the LEDs employed, obtaining root mean square error (RMSE) values below 10%. For both photocatalysts, the highest intrinsic kinetic parameters were obtained with the LED with an emission peak at 365 nm.