Preparation of TiO2-Coated Polyester Fiber Filter by Spray-Coating and Its Photocatalytic Degradation of Gaseous Formaldehyde

Abstract

Heterogeneous photocatalytic oxidation (PCO) has shown great potential for indoor air purification of gaseous pollutants. Research attention has been drawn to the synthesis of new functional photocatalysts, as well as to kinetic studies of the influences of various reaction parameters, e.g., relative humidity. Nevertheless, when applied for practical use, the coating method and coating stability of are also important factors that will directly affect the removal efficiency. In the present study, a simple and economical spray coating method was developed to effectively immobilize TiO 2 nanoparticles onto a polyester fiber filter at low temperature. Colloidal silica was added as a binder in the coating suspension. PCO efficiency evaluation of the coating was carried out using gaseous formaldehyde. The results indicate that the formaldehyde removal rate is associated with the amount of binder added. The highest removal rate was achieved for a coating with the TiO 2 to binder (SiO 2 equivalent) mass ratio of 1:1, with the results supported by XRF, SEM, FTIR and BET analyses. As compared to the conventional dip coating method, the spray-coated sample showed much higher PCO efficiency and stability, which may be mainly attributed to the more uniform dispersion of the catalyst and the stronger binding formed during high pressure spray coating. This coating method has great potential for large-scale applications of immobilized photocatalyst for indoor air purification.

Preparation of a TiO2-coated photocatalytic air filter for use with an electrostatic air filter pack for xylene removal

“…This study shows that high binder dosage of PEG 4000 might result in enhancing the coating agglomerate size and decreasing the surface area limiting the contact between TiO 2 and xylene molecules. This interpretation is in agreement with a later study 27 . However, the xylene degradation with PCO may be limited by other parameters such as adsorption, UV light intensity, relative humidity, mass transfer rate 4,5,28 .…”

Technical Note: Concerns on the Use of Ozone Scrubbers for Gaseous Carbonyl Measurement by DNPH-Coated Silica Gel Cartridge

“…Without correcting the concentration values by the measured collection efficiencies, the next abundant carbonyl species were acetaldehyde and acetone. Higher carbonyl concentrations were observed at the urban sampling location compared to those measured at the rural location, suggesting the dominance of anthropogenic sources (e.g., vehicular and cooking emissions) in local carbonyl emissions (Ho and Yu, 2002;Ho et al, 2006;Hwang et al, 2011;Panagopoulos et al, 2011;Han et al, 2012;Ho et al, 2012;Wang et al, 2012). Unsaturated carbonyls including acrolein and crotonaldehyde were detected but their abundances were uncertain or inaccurate.…”

Removal of Low-Concentration Formaldehyde by a Fiber Optic Illuminated Honeycomb Monolith Photocatalytic Reactor

“…and Fujishima, 1998;Ao et al, 2004;Yu et al, 2006a;Zuo et al, 2006;Hodgson et al, 2007;Wang et al, 2007;Yang et al, 2007a;Shie et al, 2008;Zhang and Liu, 2008;Chen et al, 2009;Mo et al, 2009;Lu et al, 2010;Aïssa et al, 2011;Bourgeois et al, 2012;Han et al, 2012;Dozzi et al, 2013). In the photocatalytic oxidation, the ultraviolet (UV) radiation with energy above the band-gap of titanium dioxide (TiO 2 ) (wavelength < 385 nm) can induce the formation of electron-hole pairs and generate hydroxyl radicals further on the UV-illuminated TiO 2 surface, and then the oxidation of organic contaminants to H 2 O, CO 2 and other final products is mediated by hydroxyl radicals (Anpo et al, 1991;Yu et al, 2006b;Zuo et al, 2006;Hodgson et al, 2007;Yu and Lee, 2007;Mo et al, 2009Sun et al, 2010Yu et al, 2010;Kandiel et al, 2013;Klementova and Zlamal, 2013;Silva et al, 2013).…”