In this work, macroscopic TiO2 monoliths are proposed to serve simultaneously as support and co-catalyst in a continuous flow photoreactor. The impregnation via one-pot of mesoporous TiO2 with CdS (m-TiO2/CdS) and CuO (m-TiO2/CuO) nanoparticles enabled the formation of photocatalytic heterojunctions retaining high specific surface area (~ 100 m2/g). The impregnated monoliths of 2-3 mm in size were employed as photocatalysts to inactivate airborne bacteria under blue light, reducing the emission of living airborne bacteria up to 0.1% and 37.7% when using m-TiO2/CdS and m-TiO2/CuO, respectively. Bacteria were characterized and quantified by flow cytometry and cell lysis was confirmed by SEM, detecting collapsed bacteria. Along 96 h of continuous photocatalysis at a flow rate of 2.2 L/min, the cell concentration presented maxima and minima due to the adsorption-desorption stages of bioaerosols over the catalysts, in concordance with thermal gravimetric analysis. The reactivation of catalysts was achieved by calcination at 400 °C, however, after a third re-cycle, the photocatalytic activity for all monoliths was practically negligible because the physicochemical surface changes hinder the adequate bioaerosol adsorption. These porous systems could emerge as promising gas-phase catalysts since the mass transport is facilitated by porosity and the release of catalyst nanoparticles is avoided by the active support, providing a safe and viable model for bioaerosols inactivation to improve indoor air quality with the use of interior lighting.
Supplementary information: The online version contains supplementary material available at 10.1007/s10562-021-03659-9.
Keywords: Airborne bacteria; CdS and CuO nanoparticles; Photocatalysis; TiO2 monolith; Visible-light-driven.
© The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2021.