以钛氧有机物水解法制备的TiO₂胶体为絮凝剂和光催化剂，对二次纤维造纸厂的混合污水进行了胶体絮凝－光催化处理，并对絮凝机理以及光催化反应的最佳条件进行了探讨．研究表明: 平均粒径为13. 5 nm 的TiO₂胶体粒子具有良好的光催化活性; 在pH值为4、TiO₂用量( 纯TiO₂质量分数) 为0. 025% 的条件下对污水进行絮凝处理，然后在pH 值为3、TiO₂用量为0. 050%的条件下进行光催化处理时，水样COD 从909. 7 mg /L 降至103. 0 mg /L，总的COD 去除率为88. 7%; TiO₂胶体对污水中细小纤维与胶粘物粒子的絮凝主要是依靠纳米粒子在细小纤维和胶粘物质之间的架桥作用; 在光催化过程中，反应前期TiO₂胶体具有高的COD 去除率，6 h 后反应趋于平缓; 该造纸污水光催化剂用量少，能回收再利用，可有效降低能耗及水处理成本．

In this paper,the flocculation-photocatalysis treatment of the mixed wastewater from secondary-fiber paper mill was carried out,with TiO₂ colloid prepared by the hydrolysis of titanyl organic compound as the flocculant and the photocatalyzer. Then,the flocculation mechanism of TiO₂ colloid and the optimal photocatalysis conditions were investigated. The results indicate that ( 1) TiO₂ colloid particles with the average diameter of 13. 5 nm is of
high photocatalytic activity; ( 2) when the flocculation performs at a TiO₂ dosage of 0. 025% ( mass fraction) with a pH value of 4,and when the photocatalysis performs at a TiO₂ dosage of 0. 050% with a pH value of 3,the COD of wastewater sample decreases from 909. 7mg /L to 103.0mg /L,and the total COD removal reaches 88. 7%; ( 3) the flocculation of TiO₂ colloid is mainly due to the bridging between TiO₂ colloid and the fine fibers as well as the dissolved colloidal substances( DCS) in the wastewater; ( 4) the COD removal of TiO₂ colloid is high in the earlier stage of photocatalysis,and then slowly changes after 6 hours; and ( 5) TiO₂ colloid is a kind of reusable photocatalyzer and a small dosage of it helps to reduce the energy consumption and the cost of wastewater treatment.