Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

PHOTOCATALYTIC SELF CLEANING SURFACES FORHOUSEHOLD COOLING APPLIANCESS. Di Giulio 1 , P. Faraldi 2 , N. Russo 1 , D. Fino 1 , G. Saracco 1 and V. Specchia 11 Materials Science and Chemical Engineering Department, Politecnico di Torino,C.so Duca degli Abruzzi 24, Torino 10129 Italy,phone/fax: +39 011 0904710/4699, e-mail: nunzio.russo@polito.itPP-III-32 Indesit Company, Innovation and Technology Department,Via Lamberto Corsi 55, Fabriano (AN) 60044 Italy, phone/fax: +39 0732 668330/8201IntroductionHousehold refrigerators are meant to store and preserve food at low temperatures. Therefrigerator cabinet is a closed environment, where organics releases from stored foodrepresents the main concern and harm for users. Hygiene perception is a primary value forpotential customers: colour and shapes of inside surfaces are designed to communicate andprovide ease of cleaning. Nevertheless, cleaning of inside cabinet is still a major issue forcustomers. The work described in the present paragraph represents a novel approach torefrigerator cleaning. The potential of photo-catalysis as a self cleaning process isinvestigated. The well known oxidative properties of titanium dioxide (anatase form) isworthwhile to be investigated. TiO 2 commercial availability and cost make it suitable forwhite goods market.A low temperature in-situ synthesis was adopted to obtained a catalytic layer that wascharacterised by Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD), toverify layer integrity and morphology. Photocatalytic activity towards organic dirtdecomposition was measured through the oxidation of various organic dyes, as theperceivable decolouring of the dirt can be a clear activity indicator for users.ExperimentalThe refrigerator-grade polystyrene liner requires a tailored TiO 2 deposition process. Theinvestigated TiO 2 substrate was polystyrene (PS) extruded in sheets, being the typical materialused as liner for the refrigerator internal cabinet. For this purpose, a low temperature coatingprocess was applied to achieve a photocatalytic layer, based on the production of anamorphous type titanium hydroxide gel, to be used as a coating precursor [1,2]. Thepreparation method described in literature uses, as precursor, a titanium tetrachloride aqueoussolution, to be reacted with an ammonium hydroxide solution in an acidic range of pH 2 to 6.Being TiCl 4 a quite dangerous and difficult compound to handle in an industrial process, theauthors decided to modify the process, by using an organic titanium oxide precursor, namelytitanium isopropoxide Ti(OC 3 H 7 ) 4 , in the same conditions.307