可见光照射下染料茜素红的光催化降解机理

MECHANISM OF PHOTOCATALYTIC DEGRADATION OF DYE POLLUTANT—ALIZARIN RED UNDER VISIBLE LIGHT RADIATION

研究了 可见光（ ≥４２ ０ ｎ ｍ ） 照射下 染料茜素 红在空气 饱和 的 Ｔｉ Ｏ２ 水溶 液中 发生 的光 催化降解过 程． 借 助紫外 、核磁、顺 磁、红外 、色质 联用等手 段，发现 染料茜素 红的光 催化 降解 过程 符合 Ｌａｎｇ ｍ ｕｉｒ Ｈｉｎｓｈｅｌｗ ｏｏｄ 模型，在 降解过程 中产 生了 过氧 化 物． 核磁 、红 外和 色质联 用等 结 果证 实，主要降解 中间产 物为邻苯 二甲酸 ． Ｃ Ｏ Ｄ 测试 结 果表 明， 其矿 化产 率 达３ ０ ％ ， Ｅ Ｓ Ｒ 结 果证 实， 在降解过程 中有 ⒒ Ｏ Ｈ 自由基 生成，说 明其与 染料的降 解机理有 密切联 系．

Alizarin red can be rapidly degraded in air equilibrated aqueous TiO 2 dispersion under visible light radiation ( λ ≥420 nm). UV Vis, NMR, spin trapping ESR, IR and GC MS were employed to study the photodegradation process of alizarin red. The degradation process was also fit for the Langmuir Hinshelwood model, and the peroxide intermediates were observed during the process. The principal intermediate was phthalic acid according to the results of NMR, IR and GC MS. The mineralization yield of alizarin red was ca 30% by means of COD measurement. H radical was formed during the degradation process, and it was closely related to the degradation of the dye under visible light radiation.