Formaldehyde removal from air via a rotating adsorbent combined with a photocatalyst reactor: Kinetic modeling

A novel rotating honeycomb adsorbent coupled with a photocatalytic reactor demonstrated by Shiraishi et al. is modeled here. In operation, the air pollutant formaldehyde was adsorbed from a simulated room (10 m3) onto a slowly rotating honeycomb, which then passed slowly through a small chamber (0.09 m3) in which locally recirculated heated air desorbed the formaldehyde and carried it through a photocatalytic reactor, which oxidized the desorbed material. The regenerated rotor-adsorbent then rotated back into the airtight chamber. This system was modeled at steady states and transient states to determine adsorption, desorption, and photocatalyst pseudo-first-order rate constants at the appropriate temperatures (ambient temperature for adsorption, 120–180 °C for desorption and photocatalysis). Intensity-corrected values for the photocatalytic rate constant kcatkcat (cm2/(mW s)) deduced from fitting our model to the data of Shiraishi et al. were in good agreement with those calculated from five literature reports for formaldehyde photocatalytic destruction.