Apatite-coated titanium dioxide photocatalyst for air purification

A multifunctional composite material, titanium dioxide covered with apatite, has been developed for application in air purification and as an antimicrobial, antifungal, and antifouling coating. This composite can absorb and decompose bacteria and various other materials. TiO2 powder was soaked in a simulated physiological solution containing phosphate ions for periods of about 1 h at 37 degreesC. The composite material has the following characteristics: (1) the apatite adsorbs contaminants even without exposure to light; (2) material adsorbed by the apatite is decomposed by the titanium dioxide photocatalyst on exposure to light; (3) the apatite is used as an inert spacer, allowing blending of the material with resins, organic coatings, and other organic materials; (4) though the photocatalyst requires some time to fully decompose organic materials, capture of contaminants by the apatite ensures complete decomposition. (C) 2004 Elsevier B.V. All rights reserved.