对硝基苯酚臭氧化反应动力学研究

Kinetics of Ozonation of p-Nitrophenol in Aqueous Solutions

在T=298K,pH=2.1～6,采用停流光谱仪研究了对硝基苯酚与臭氧在水溶液中的臭氧化反应动力学。实验结果表明,对硝基苯酚臭氧化总的反应是2级,对臭氧浓度和对硝基苯酚浓度分别为1级。臭氧化反应速率常数随溶液pH值的增大而增大;T=298K时,当pH值从2.1变化到6,总的反应速率常数从5.88×104L(mol·s)-1增大到1.56×106L(mol·s)-1。为了验证其适用性,对臭氧在搅拌釜中在对硝基苯酚溶液中的吸收过程进行了模拟。采用MATLAB软件求解臭氧在搅拌釜中在对硝基苯酚溶液中吸收过程的质量平衡方程,模拟得到了吸收过程中臭氧和对硝基苯酚浓度的变化,并与实验值进行了比较。结果表明,在85%的对硝基苯酚降解之前,模拟值和实验值能很好地一致。在反应末期,模拟值和实验值出现了一定的偏差。

A stoppedflow spectrophotometer system was applied to study the kinetics of the ozonations between dissolved ozone and pnitrophenol in aqueous solutions of pH values varying from 2.1 to 6 at 298K. It was experimentally Showed that the overall ozonation reaction of pnitrophenol was second order, and first order for each reactant, respectively. The ozonation rate of pnitrophenol increased with the solution pH in the range of 2.1 to 6 investigated. As the pH value increases from 2.1 to 6, the overall rate constant increased from 5.88×104 to 1.56×106 L(mol·s)-1 at 298K. The mass balance equations about ozone absorption in pnitrophenol solution in a stirredtank operating in the complete mixing mode were solved by utilizing the Matlab ODE program. The ozone concentrations and the concentrations of pnitrophenol during absorption experiments were simulated. The results were compared with the measured concentrations. The simulated results indicated the simulated concentrations of pnitrophenol agreed well with the measured concentrations up to 85% consumption of pnitrophenol. As the pnitrophenol concentration declined to certain level, there were a few of deviations between the simulated and measured concentrations.