甲酸光催化降解过程中的过氧化氢生成机制

Relationship between photocatalytic degradation of formic acid and formation of hydrogen peroxide

考察了在3种紫外光源(黑光灯、杀菌灯、臭氧灯)的照射下,分别以TiO2与Pd/TiO2为催化剂,甲酸降解过程中过氧化氢的生成机制.研究发现,在黑光灯/催化剂条件下,可在纯水中生成过氧化氢,但当催化剂缺失时几乎不能生成.在黑光灯或杀菌灯照射下,甲酸溶液在有催化剂存在时可被稳定分解,但当催化剂不存在时则分解非常缓慢.对各种光源而言,Pd/TiO2比TiO2催化降解甲酸的效果好.对光源条件的比较发现,甲酸分解速度与过氧化氢生成速度依次为臭氧灯>杀菌灯>黑光灯.结果表明,甲酸光催化分解初速度与过氧化氢生成的初速度呈正比,过氧化氢生成是光催化降解有机物的关键因素.

The formation of H2O2 in the decomposition of HCOOH in water with TiO2 or Pd/TiO2 as catalyst under irradiation with one of the three types of UV lamps （blacklight blue fluorescent lamp, BL; germicidal lamp, GL; ozone lamp, OL） was investigated. Irradiation with UV light from the BL synthesized H2O2 from water in the presence of the photocatalyst. Similarly, irradiation with UV light from the BL or GL decomposed HCOOH in the presence of the photocatalyst. Under irradiation with every light source, HCOOH was decomposed more quickly with Pd/TiO2 than with TiO2. The rate of decomposition of HCOOH was large and in decreasing order of OL, GL and BL. The rate and amount of H2O2 formed were also large and in the same order. The result showed that the initial rate of decomposition of HCOOH was directly proportional to the initial rate of formation of H2O2, indicating that the photocatalytic activity was strongly dependent on the capability of the photocatalyst to form H2O2.