枞酸和松香在紫外光辐照下的氧化反应动力学

Oxidation Reaction Kinetics of Abietic Acid and Rosin under Ultraviolet Light Irradiation

设计了紫外光辐照下枞酸和松香的氧化反应装置,采用紫外分光光度法实时测定它们的氧化反应过程,计算氧化反应动力学常数(kb)和反应活化能(Ea),考察光量子产率(Φ)和光强度(I)对氧化反应动力学的影响.结果表明,枞酸和松香的光氧化反应均呈表观一级反应,它们的速率常数的对数与光强度的对数均呈线性关系.枞酸在20,25和35℃下的关系式分别为:lnkb=0.9911lnI-8.860,lnkb=0.8786lnI-8.069和lnkb=0.8364lnI-7.690.松香于20℃下的关系式为:lnkb=1.204lnI-10.49.枞酸初始反应的光量子产率Φ为0.471.且枞酸在不同光强度下的活化能与光强度的对数成线性关系,线性方程为:Ea=-7.549lnI+60.02.

We designed an oxidation reactor for abietic acid and rosin oxidation under ultraviolet light irradiation. The oxidation process of abietic acid and rosin were determined by UV spectrophotometry and the rate constants （kb） and activation energy （Ea） of the oxidation process were calculated. The kinetic effect of the quantum efficiency （Φ） and the light intensity （I） on the photooxidation reaction were also investigated. The experimental results showed that the photooxidation kinetics of abietic acid and rosin were pseudo first order. The relationship between the natural logarithm of rate constant （lnkb） and the natural logarithm of the light intensity （lnI） is linear. When the reaction temperatures were 20, 25, and 35 ℃, the apparent reaction rate constants of abietic acid were： lnkb=0.9911lnI-8.860, lnkb=0.8786lnI-8.069, and lnkb=0.8364lnI-7.690, respectively. At 20 ℃, the apparent reaction rate constant of rosin was lnkb=1.204lnI-10.49. The initial quantum efficiency of abietic acid is 0.471 and the relationship between the activation energy （Ea） of abietic acid and the natural logarithm of the light intensity （lnI） is also linear： Ea=-7.549lnI＋ 60.02.