A facile method to prepare translucent anatase thin films in monolithic structures for gas stream purification
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.
KeywordsGas-phase photocatalysis VOCs Honeycomb structures Solar light Bacteria inactivation TiO2
Financial support was provided by project PTDC/EQU-EQU/100554/2008 (AIRPHOTOXI). This work was also financially supported by Project POCI-01-0145-FEDER-006984—Associate Laboratory LSRE-LCM funded by FEDER through COMPETE2020—Programa Operacional Competitividade e Internacionalização (POCI)—and by national funds through FCT—Fundação para a Ciência e a Tecnologia. Caio Rodrigues-Silva acknowledges CAPES (2013:8674/13-2) and FAPESP (2014:2014/16622-3) research scholarship and the project CAPES/FCT 308/11 for financial support. R.A.R. Monteiro gratefully acknowledges FCT for his post-doc research fellowship, SFRH/BPD/112900/2015. V.J.P. Vilar and A.M.T. Silva acknowledge the FCT Investigator 2013 Programme (IF/00273/2013 and IF/01501/2013, respectively).
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