Application of a hybrid system comprising carbon-doped TiO₂ film and a ceramic media-packed biofilter for enhanced removal of gaseous styrene

It is difficult to efficiently remove gaseous styrene using a TiO₂ film-coated photoreactor under UV light. Therefore, we used a hybrid system consisting of a carbon-doped TiO₂ (C-TiO₂) film and a media-packed biofilter in order to enhance the removal efficiency (RE) of gaseous styrene compared to that of a pure (undoped) TiO₂ photoreactor. The C-TiO₂ was synthesized by a sol–gel combustion method, and its absorption spectrum was stronger that of pure (undoped) TiO₂ in the UV–vis range. The resultant RE of the C-TiO₂ film was 113–200% higher than that of the pure TiO₂ film. The initial RE of the photoreactor for input styrene concentrations of 630mgm⁻³, 420mgm⁻³, and 105mgm⁻³ was 20.6%, 29.8%, and 40.0%, respectively. When the biofilter was added, the RE increased to 93.3%, 97.9%, and 99.0%, respectively. Thus, application of the hybrid system consisting of both a photoreactor coated with a C-TiO₂ film and a biofilter is advantageous in terms of the removal efficiency of gaseous styrene.