A facile method to prepare translucent anatase thin films in monolithic structures for gas stream purification

Caio Rodrigues-Silva, Ricardo A. R. Monteiro, Márcia Dezotti, Adrián M. T. Silva, Eugénia Pinto, Rui A. R. Boaventura, Vítor J. P. Vilar

In the present work, a facile method to prepare translucent anatase thin films on cellulose acetate monolithic (CAM) structures was developed. A simple sol-gel method was applied to synthesize photoactive TiO2 anatase nanoparticles using tetra-n-butyl titanium as precursor. The immobilization of the photocatalyst on CAM structures was performed by a simple dip-coating method. The translucent anatase thin films allow the UV light penetration through the CAM internal walls. The photocatalytic activity was tested on the degradation of n-decane (model volatile organic compound-VOC) in gas phase, using a tubular lab-scale (irradiated by simulated solar light) and pilot-scale (irradiated by natural solar light or UVA light) reactors packed with TiO2-CAM structures, both equipped with compound parabolic collectors (CPCs). The efficiency of the photocatalytic oxidation (PCO) process in the degradation of n-decane molecules was studied at different operating conditions at lab-scale, such as catalytic bed size (40-160 cm), TiO2 film thickness (0.435-0.869 μm), feed flow rate (75-300 cm3 min-1), n-decane feed concentration (44-194 ppm), humidity (3 and 40%), oxygen concentration (0 and 21%), and incident UV irradiance (18.9, 29.1, and 38.4 WUV m-2). The decontamination of a bioaerosol stream was also evaluated by the PCO process, using Pseudomonas aeruginosa (Gram-negative) and Staphylococcus aureus (Gram-positive) as model bacteria. A pilot-scale unit was operated day and night, using natural sunlight and artificial UV light, to show its performance in the mineralization of n-decane air streams under real outdoor conditions. Graphical abstract Normally graphics abstract are not presented with captions/legend. The diagram is a collection of images that resume the work.