Photocatalytic activity of TiO2 crystallite-activated carbon composites prepared in supercritical isopropanol for the decomposition of formaldehyde

An effort was made to develop photocatalytic TiO2 crystallite-activated carbon (TiO2-AC) composites from tetraisopropyl titanate (TPT)-soaked activated carbon in supercritical isopropanol. It was subsequently found that TPT in supercritical isopropanol could be effectively converted to the anatase form of the TiO2 crystallites. The prepared composites, composed of activated carbon as an adsorbent and the anatase form of TiO2 as a photocatalyst, were evaluated for their adsorption capacity and subsequent photocatalytic activity against formaldehyde, one of the harmful air pollutants in the environment. As a result, the supercritically treated TiO2-AC composites, particularly at 300degreesC and 350degreesC, had much higher formaldehyde-decomposing ability compared to a noncomposite comprising a simple mixture of activated carbon and TiO2 granules. This indicates that the supercritical treatment can be effective for preparing the photocatalytic composites that have a high synergetic effect of adsorption and photocatalytic decomposition of formaldehyde for environmental cleaning.