苯酸液相臭氧化动力学特性的研究

Experimental observation about dynamics of oxidationof phenol in liquid phase

应用Stopped-flow光谱仪对苯酚在288～313K温度和pH=3.2～9.3的液相臭氧化反应动力学特性进行了实验研究。通过实验及分析认为:苯酚的O_3氧化降解反应中,O_3与苯酚的计量比为3;在不同酸度的实验条件下,苯酚的液相O_3氧化降解的途径及动力学不同。

The present research concerns mechanism and rate of reaction between dissolved Ozone and phenol in homogeneous so-lutions. The stopped- flow spectrophotometer was employed to obtain absorbances during reactions;the kinetic experiments were conduct-ed at temperatures varying from 288 to 313 K in aqueous solutions with pH values ranging from 3.2 to9.3 (the pH values of aqueous solu-tions were regulated by using H2 SO4 and NaOH .).The conclusion coming from experiments and analyses is that the stoichiometric ratio of ozonation reaction between O3 and phenol are 3. We think that the the pathways and the reaction kinetics are different in various acidity as that the absorbance curves vs time of the mixtures of O3 and phenol are difference in various acidity. At pH3.2, the overall kinetics of the ozonation of phenol is 0.3 order with respect to the concentration of phenol and independent of the concentrations of the ozone . At pH4.0 and 6.2, the overall kinetics of the ozonation of phenol is 1.4 order with 0.4 order in the concentration of phenol and first order in the concentrations of the ozone . At pH9. 3, the overall kinetics of the ozonation of phenol is second order with first order each in the concentration of phenol and ozone . The rate constant increases with temperature, and the activation energy of 17. 1KJ/mol at pH3.2 was obtained .