Surface Treatment of Photocatalyst Metal Supports for VOCs Abatement Applications

Abstract: In this work, the preparation of photocatalysts’ metal support for applications in purification of industrial gas emissions has been studied. The supports normally used in literature are ceramics, but they are not suitable for industrial applications. Stainless steel and aluminium are much more common in full-scale reactors and were therefore chosen in this investigation. Chemical etching, anodisation, electrochemical DC etching and AC etching treatment methods were used to modify the surface morphology of aluminium and stainless steel plates in order to improve the mechanical stability of photocatalyst (TiO2) coating. Two-part epoxysiloxane hybrid (ESH) and sodium silicate adhesives have been evaluated for use as TiO2 binder. Dip and spray coating techniques were employed for preparing TiO2 coatings on blank plates, pretreated plates, ESH and sodium silicate coated plates. Stainless steel electrochemically etched in dilute aqua regia gave the most mechanically stable coating. It was demonstrated that a high microscale surface roughness of the support improves the mechanical stability of TiO2. Additionally, photocatalytic performance of the coating was higher than that coated on ceramic support. The mechanical stability of TiO2 coated on ESH and sodium silicate using dip and spray coating techniques was exceedingly improved. However, Energy Dispersive Spectroscopy (EDS) analysis showed that TiO2 was embedded in the adhesives. Nevertheless, sprinkling of TiO2 powder on sodium silicate presented a very stable coating regardless of high TiO2 loading. It was also shown that coating of sodium silicate on pretreated plates did not a↵ect the mechanical stability of TiO2 coating. A well coated and uniform surface of TiO2 was achieved by spray coating technique.