| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a high-purity silica-photocatalyst composite capable of exerting a photocatalytic action efficiently and achieving a high degree of purification of a target material, e.g. water or air. <P>SOLUTION: A high-purity silica is prepared through (A) an alkali dissolving process of mixing powder of siliceous shale with an aqueous alkali solution to form an alkaline slurry of a pH of ≥11.5 so as to dissolve Si, Al and Fe in the powder of siliceous shale in the solution and subjecting the alkaline slurry to solid-liquid separation to obtain a solution containing Si, Al and Fe, (B) an Si solution separation process of mixing the solution obtained in the process (A) with an acid to make the pH equal to or higher than 10.3 and lower than 11.5 to precipitate Al and Fe in the solution and carrying out sold-liquid separation to obtain a solution containing Si and (C) a silica separation process of mixing the solution obtained in the process (B) with an acid to make the pH equal to or higher than 9.0 and lower than 10.3 to precipitate Si in the solution and carrying out solid-liquid separation to obtain a solid content containing SiO<SB>2</SB>. The high-purity silica-photocatalyst composite is formed by causing titanium oxide serving as a photocatalyst to be supported with the high-purity silica. <P>COPYRIGHT: (C)2011,JPO&INPIT |
