高等学校化学学报

高等学校化学学报 ›› 2002, Vol. 23 ›› Issue (12): 2313.

• 研究论文 • 上一篇    下一篇

正十六烷光催化降解的羟自由基测定及其反应速率常数

钟萍, 孔令仁, 刘光明, 眭云霞   

  1. 南京大学环境学院, 污染控制与资源化研究国家重点实验室, 南京210093
  • 收稿日期:2002-01-10 出版日期:2002-12-24 发布日期:2002-12-24
  • 通讯作者: 孔令仁(1941年出生),男,教授,博士生导师,从事有机污染物深度光氧化研究.E-mail:linrenkon@sohu.com E-mail:linrenkon@sohu.com
  • 基金资助:

    国家自然科学基金(批准号:29877011)资助

EPR Measurement of Hydroxyl Radicals and Rate Constant of n-Hexadecane Photocatalytic Degradation

ZHONG Ping, KONG Ling-Ren, LIU Guang-Ming, SUI Yun-Xia   

  1. State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093, China
  • Received:2002-01-10 Online:2002-12-24 Published:2002-12-24

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被引次数

9

摘要： 以5,5-二甲基-1-吡咯啉-N-氧化物(DMPO)为自旋捕集剂,采用电子顺磁共振(EPR)方法,在光照的TiO2磷酸缓冲水溶液(pH=7.4)中检测到羟自由基的自旋加合物(DMPO-OH),其强度随光照时间增加而加大.在1min时达到稳态,此时DMPO-OH的产生和猝灭达到平衡.根据已知的羟自由基(HO·)与DMPO结合的速率常数k0,推导出纳米级TiO2光催化生成羟自由基氧化正十六烷(n-C16H34)的速率常数k=5.0×1011mol-1·L·s-1.

关键词: 光催化降解, 羟自由基, 电子顺磁共振, 纳米TiO2, 正十六烷

Abstract: Spin trapping technique was used to detect the free radicals formed upon light irradiation of TiO2 in aqueous solutions. 5,5-dimethylpyrroline-N-oxide(DMPO) was used as a spin trapper. The Electron paramagnetic resonance( EPR) signal obtained 1 min after reaction initiated by 180 W mercury lamp irradiation with a mixture of 1 g/L TiO2, 0.05 mol/L DMPO in phosphate buffer(pH=7.4) gave the 1/2/2/1 quartet with hyperfine splittings of a N=a H=1.49×10-3 T, g=2.005 0, which were typical peaks of DMPO-OH. A model was used to speculate on the free radical mechanisms of n-hexadecane photodegradation by TiO2 in aqueous solutions. The intensity increased with increase of the irradiation time and the steady state was achieved at 1 min light irradiation. By employing the known rate constant for the reaction of hydroxyl radicals(HO ·) with the DMPO, the rate constant k=5.0×1011 mol-1·L·s-1 for the reaction of hydroxyl radicals with n-hexadecane could be obtained. In conclusions, TiO2 photocatalytic reaction proceeded in a free radical mechanism.

Key words: Photocatalytic degradation, Hydroxyl radicals, EPR, Nano TiO2, n-Hexadecane

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