摘要
选择了5种水体中常见的阴离子(Cl-,SO42-,HPO42-/HPO24-,HCO3-/CO32-和NO3-),分别考查了其对TiO2薄膜光催化降解模拟甲醛废水的反应速率的影响;从上述离子的光吸收,对.OH的捕获及其生成的相应的无机自由基的氧化作用以及与甲醛的竞争吸附3个方面讨论了上述离子影响TiO2薄膜光催化降解模拟甲醛废水的反应速率的原因。结果表明,HCO3-/CO32-对TiO2薄膜光催化降解甲醛具有抑制作用,Cl-和SO24-的影响不大,H2PO4-/HPO42-和NO3-具有促进作用。造成上述结果的主要原因是HCO3-/CO23-具有很强的.OH捕获作用;Cl-,SO24-对.OH捕获作用以及竞争吸附都较弱;H2PO4-/HPO24-在TiO2表面具有较强的吸附能力,释放出的H+起到了酸催化剂的作用;NO3-在紫外光的照射下可以产生.OH,此外NO3-作为电子受体而降低了TiO2表面光生电子和空穴的复合几率。
The effects of five inorganic anions（Cl^-,SO4^2- ,HPO4^2- /HPO4^2- ,HCO3^- /CO3^2- and NO3^-）which are commonly present in water and wastewater on the photocatalytic activity of TiO2 thin films for the photodegradation of formaldehyde were investigated. They were observed from three respects：UV-vis absorption by inorganic anions, OH scavenging by inorganic anions and direct oxidation of formaldehyde by anion radicals, and adsorption of inorganic anions to the TiO2 surface. The results indicatedthat, HCO3^-/CO3^2- significantly inhibited formaldehyde oxidation due to its potentness of · OH scavenging,instead of Cl^- and SO4^2- ,which had neither hydroxyl radical scavenging nor direct oxidation by the corresponding anion radicals. H2PO4^2-/HPO4^2- enhanced formaldehyde photocatalytic oxidation mostly because of its ability of adsorption to the TiO2 surface,which result in release of H ^＋ playing a catalyst role. NO3^- also promoted formaldehyde oxidation,which was lied in two aspects ： firstly, · OH produced under irradiated ultraviolet in the presence of NO3 ^-, secondly,NO3^- act as electron acceptor to reduce the recombination of electron and hole on the TiO2 surface.
出处
《环境工程学报》
CAS
CSCD
北大核心
2008年第10期1339-1344,共6页
Chinese Journal of Environmental Engineering
基金
兰州交通大学"青蓝"人才工程基金资助项目(QL-06-04-A)
甘肃省自然科学基金项目(3ZX062-B25-009)
关键词
无机阴离子
TIO2薄膜
光催化降解
甲醛
羟基自由基
吸附
inorganic anions
TiO2 thin films
photocatalytic degradation
formaldehyde
hydroxyl radical
adsorption
