Effect of silanization of titanium dioxide on photocatalytic decomposition of 2,4-dinitropheonol under irradiation with artificial UV light and sunlight

BACKGROUND: TiO₂-based heterogeneous photocatalysis is an effective way to degrade harmful refractory organic compounds. However, the rate of photocatalytic reaction is significantly decreased by film diffusion resistance and several other factors. To overcome this problem, TiO₂ immobilized on a stainless steel screen is hydrophobically treated using a (γ-aminopropyl) triethoxysilane-toluene solution and the performance of the silanized TiO₂ for the photocatalytic decomposition of 2,4-dinitrophenol (2,4-DNP) is investigated. RESULTS: The reactant 2,4-DNP is slowly decomposed when its aqueous solution is treated using an unsilanized TiO₂ screen without mixing the solution, whereas the rate of decomposition is certainly increased by use of a silanized TiO₂ screen, and further increased by mixing the solution. The use of sunlight as a UV light source provides a higher rate of decomposition than does the use of an artificial UV lamp. The rate of decomposition in a well-mixed solution is less affected up to 1.5 cm in solution depth. CONCLUSIONS: The use of the TiO₂ screen silanized with a 2% silane-toluene solution under liquid mixing decreases film diffusion resistance and facilitates rapid decomposition of 2,4-DNP. The simultaneous use of sunlight as a UV light source and a wind-powered propeller for liquid mixing is effective.