纳米TiO2光催化降解植物激素的活性与机理

以纳米TiO2为催化剂研究了紫外光照射下植物激素吲哚-3-乙酸和氯吡苯脲的降解过程和机理。基于吲哚-3-乙酸在278 nm处的特征吸收峰和氯吡苯脲在261 nm处的特征吸收峰,利用紫外-可见分光光度法对二者的光催化降解过程进行跟踪检测。在纳米TiO2催化下,紫外光照240 min吲哚-3-乙酸的降解率为61. 6%;紫外光照300 min氯吡苯脲的降解率高达90. 5%。动力学研究表明,吲哚-3-乙酸和氯吡苯脲的光降解反应均符合准一级反应动力学模型。通过自由基捕获实验确定·OH和·O2-是氧化分解植物激素的主要活性物质,并进一步给出纳米TiO2光催化降解植物激素的机理。在室温下实现了光催化降解植物激素,为解决环境中激素污染提供了一种可行的方法。

Activity and mechanism of nano-TiO2 photocatalytic degradation of phytohormone

The degradation process and mechanism of two phytohormones,indole-3-acetic acid and 1-( 2-chloropyridin-4-yl)-3-phenylurea under UV irradiation were studied with nano-TiO2 as catalyst. Based on the intensity changes of characteristic absorption peak of indole-3-acetic acid at 278 nm and the characteristic absorption peak of 1-( 2-chloropyridin-4-yl)-3-phenylurea at 261 nm,the photocatalytic degradation process of the two phytohormones were detected using UV-vis spectrophotometry. In the presence of nano-TiO2,the degradation ratio of indole-3-acetic acid was 61. 6% under UV irradiation for 240 min,and the degradation ratio of 1-( 2-chloropyridin-4-yl)-3-phenylurea was up to 90. 5% under UV irradiation for 300 min. Kinetic studies suggested that the photodegradation of indole-3-acetic acid and 1-( 2-chloropyridin-4-yl)-3-phenylurea was in accordance with the pseudo-first-order kinetic model. The free-radical capture experiments proved that ·OH and ·O2-are the main active substances for oxidative decomposition of the two phytohormones,and the mechanism of photocatalytic degradation of phytohormones by nano-TiO2 was further discussed. This study realized the photocatalytic degradation of phytohormones at room temperature,which provided a feasible method for solving hormone pollution in the environment.