摘要
选择了5种水体中常见的阴离子(Cl-,SO24-,HCO3-,NO3-以及HPO24-/H2PO4-),分别考察了其对TiO2薄膜光催化还原模拟Cr(Ⅵ)废水的影响.从上述离子的光吸收,对.OH的捕获作用以及与Cr(Ⅵ)的竞争吸附三个方面讨论了上述离子影响TiO2薄膜光催化还原Cr(Ⅵ)速率的原因.结果表明,体系酸性越强,越有利于Cr(Ⅵ)的还原;在pH值约为6时,HCO3-,Cl-和SO24-对TiO2薄膜光催化还原Cr(Ⅵ)具有促进作用,NO3-具有抑制作用,H2PO4-/HPO24-在低浓度时具有促进作用,而在高浓度时具有抑制作用.造成上述结果的主要原因是Cl-,SO24-和HCO3-具有较强的.OH捕获作用和在TiO2表面较低的吸附能力;H2PO4-/HPO42-在TiO2表面具有较强的吸附能力;NO3-对紫外光吸收作用降低了TiO2表面的紫外光强度以及自身光化学反应产生了.OH.
The effect of five inorganic anions （Cl-, SO4^2- , HCO3- , NO3-and HPO4^2-/HPO4^2- ） which are commonly present in water and wastewater on the photocatalytie activity of TiO2 thin films for the photocatalytic reduction of Cr（ Ⅵ ） was investigated. On the following three aspects： UV-vis absorption by inorganic anions, ~ OH scavenging by inorganic anions and adsorption of inorganic anions to the TiO2 surface. The results indicated that, the reduction rate of Cr（ VI ） by photocatalytically-induced electrons was significantly higher in acidic solutions than in for alkaline solutions. HCO3- , Cl- and SO2^4- promoted the photocatalytic reduction of Cr（Ⅵ） at pH 6 due to their potentness of · OH scavenging and adsorption to the TiO2 surface. H2PO4-/ HPO4^2- enhanced the photocatalytic reduction of Cr （Ⅵ） at lower concentration but inhibited it at higher concentration mostly because of its strong adsorption to the TiO2surface. NO3-also inhibited the photocatalytic reduction of Cr（ WI ） , by the two mechanisms ： firstly, · OH was produced under irradiated ultraviolet in the presence of NO3- , secondly, light intensity to the TiO2 surface was reduced because of adsorption by NO3-.
出处
《环境化学》
CAS
CSCD
北大核心
2009年第6期829-832,共4页
Environmental Chemistry
基金
兰州交通大学"第四批‘青蓝’人才工程基金资助"项目(QL-06-04-A)
国家水体污染控制与治理科技重大专项(2008ZX07425-005-3)
甘肃省高等学校研究生导师科研项目(20874)
