纳米TiO2薄膜耦合光催化氧化还原反应脱除水中无机氮

由溶胶-凝胶法制备了固定化二氧化钛薄膜，研究了薄膜催化剂光催化脱除含氨氮-亚硝酸氮混合液中无机氮的活性。考察了溶胶制备工艺、催化反应条件（尤其pH）对光催化活性的影响。实验证明：酸性条件有利于亚硝酸氮的还原，碱性条件有利于氨氮的氧化，通过调节pH可以获得光催化氧化氨氮和还原亚硝酸氮耦合效果。如果加入甲酸维持酸性条件，反应0．5h后再将pH调回碱性，可以大大提高光催化脱氮的效果：经过2h的光催化反应，二氧化钛膜催化总氮去除率可达50％以上。经多次试验证明附载二氧化钛薄膜不脱落，光催化活性未见减弱，可重复利用。提出了光催化脱氮的反应机理。

Immobilized TiO2 and its Photocatalytic Application in Removing Nitrogen from Water

The photocatalytic nitrogen removal from water by coupling photocatalytic oxidation of ammonia and reduction of nitrite were studied, using an immobilized TiO2 catalyst. The preparation of the catalyst films, their photocatalytic activities and effect of conditional factors(especially pH )on nitrogen removal were also investigated. Under N2 flow, Nitrite reduction was the major reaction under acidic condition, while ammonia oxidation was the main reaction under basic condition. By adjusting the pH value of the solution using formic acid, photocatalysis carried out under acidic condition first for 0.5 h to 1 h, then under basic condition by adjusting pH, increased the overall nitrogen removal level. The result of the experiment showed that after 2 h irradiation, the removal of TN more than 50% by the photocatalytic process was achieved. The catalyst film can be used repeatedly without decline of activity. A reaction mechanism was proposed for photocatalytic nitrogen removal.