Kinetic Modeling of a Photocatalytic Reactor for Indoor Formaldehyde Abatement

PASSALIA, C.; ALFANO, O.M.; CASSANO, A.E.

Montreal, Quebec, Canada

Congreso; 8th World Congress of Chemical Engineering; 2009

Formaldehyde is one of the most representative pollutants present indoors; it can affect human health, particularly the upper respiratory tract, even at low concentrations and is a suspected carcinogen. The need for its elimination has led to the study of advanced oxidation processes, among which heterogeneous photocatalysis has proven its efficiency. This work addresses the kinetic model of the photocatalytic degradation of formaldehyde in air using an experimental catalytic wall continuous reactor. A stainless steel flat plate coated with titanium dioxide was placed within the reactor; air with a known concentration of formaldehyde flows over both sides of the plate. The energy source for the ultraviolet radiation that initiates the degradation reactions is a group of black light lamps on each side of the reactor's windows. A kinetic model for the degradation of formaldehyde in air was proposed, based on published literature; a reaction rate expression was obtained and combined to the macroscopic mass balance for the pollutant in the reactor. Once determined the kinetic control regime for the reactor, experiments were conducted according to an experimental design with three levels for the three operating variables of the photocatalytic reaction rate: the concentration of formaldehyde, the relative humidity and the level of radiation. Kinetic parameters were estimated from the experimental data and the reactor model, applying a nonlinear regression procedure. The photocatalytic oxidation process for the removal of formaldehyde in air proved to be feasible and reasonably efficient under the operating conditions analyzed.