摘要
分别采用两种光催化剂(TiO2与Pd/TiO2)和三种紫外光源(黑光灯、杀菌灯、臭氧灯)分解水溶液中的甲醛,同时以酶法测定光催化降解过程中生成的低浓度过氧化氢.发现波长较短的紫外光源生成过氧化氢的浓度较高.当以臭氧灯为光源时,无论是否有催化剂存在,生成的过氧化氢浓度都在50mmol·m-3以上,因为185nm以下的紫外光可以直接由水与溶解氧生成臭氧,而后生成过氧化氢.不管有无催化剂存在,在臭氧灯作用下,甲醛溶液中生成的过氧化氢浓度高于纯水中生成的过氧化氢浓度.但是,在以黑光灯或臭氧灯为光源时,上述结果正好相反.此外,对于每种光源而言,当采用Pd/TiO2代替TiO2时,甲醛的分解和过氧化氢的生成都得到加强.甲醛光催化分解速率与相同条件下纯水中过氧化氢的生成速率呈正比,表明光催化降解的活性与光催化生成过氧化氢的能力近似呈正相关.
To characterize the photocatalytic reaction more clearly, HCHO in water has been decomposed using TiO2 or Pd/TiO2 irradiated with three types of UV lamps （blacklight blue fluorescent lamp, BL, germicidal lamp, GL, and ozone lamp, OL） and the concentration of H2O2 formed in parallel has been studied by introducing an enzymatic method in order to accurately measure a low concentration of H2O2. UV light with a shorter wavelength produces a larger amount of H2O2 at a higher rate. Irradiation with UV light from the OL produces H2O2 at a concentration of more than 50 mmol · m^-3 in both the presence and absence of the photocatalyst because the UV light with a wavelength of 185 nm can also produce H2O2 via the formation of ozone from water and dissolved oxygen. The H2O2 concentration measured in the HCHO decomposition is higher than that formed from only water by UV light or by the photocatalyst under UV-irradiation. This relation is reversed with the BL and GL. In every light source, the rates of decomposition and formation of H2O2 are increased by depositing Pd on TiO2. The rate of decomposition of HCHO in the presence of the photocatalyst is directly proportional to the rate of H2O2 formed from only water by UV light or by the photocatalyst under UV-irradiation, indicating that the photocatalytic activity is closely related to the capability of the photocatalyst to form H2O2.
出处
《环境化学》
CAS
CSCD
北大核心
2005年第5期520-524,共5页
Environmental Chemistry
基金
江苏省创新人才(学术)项目(No.BK2004401).
