Modeling of a TiO2-coated quartz wool packed bed photocatalytic reactor

A fixed-bed, photocatalytic laboratory reactor aimed to degrade pollutants from water streams was designed and built. Quartz wool coated with a thin film of TiO2 was employed as the reactor filling. The photocatalyst was placed in the reactor forming a loose packing to guarantee the intimate contact among reactants, photons, and the photocatalytic surface. This reactor was employed to study the photocatalytic decomposition of a model pollutant (formic acid). A reactor–radiation–reaction model was developed, which was comprised of the reactor mass balance, radiation model, and kinetic model for the degradation of formic acid. The local superficial rate of photon absorption, which was necessary to evaluate the kinetic, was obtained from the results of a radiation model. The Monte Carlo approach was employed to solve the radiation model, where the interaction between photons and the TiO2-coated fibers of the packing was considered. The kinetic model was derived from a plausible kinetic scheme. Experimental results obtained in the packed-bed reactor, operating in a differential mode and without mass transfer limitations, were used to estimate the parameters of the kinetic model. A satisfactory agreement was observed between model simulations with the derived parameters and experimental results, with a root mean square error less than 8.3%.