紫外光辐射下臭氧在水中的分解动力学

研究了紫外光辐射下臭氧在水中的分解过程。实验表明，稳态液相臭氧浓度随气速的增加而增加，但随pH值和紫外光强度的增加而降低。根据双膜理论建立了臭氧分解过程的动力学模型，并得出了臭氧分解速率常数的迭代计算式。由计算结果知，在恒定温度（30℃）下，速率常数与气相速率和pH值无关，而与紫外光强度的0.617次方成正比。

Decomposition Kinetics of Ozone in Water with Ultraviolet Radiation

A methodology was given for determining first-order rate constants (k1) of ozone decomposition in water with ultraviolet (UV) radiation. The experiments were conducted at a constant temperature of 30C with gas velocity ranging from 0.98 to 4.09 cms-1, pH from 2.0 to 8.0, and UV light intensity (I) from 0.2 to 0.6 Wm-2. A semi-batch bubble-column reactor was employed in which the gaseous ozone was absorbed into 0.05 molL-1 phosphate buffer and simultaneously underwent auto-decomposition, and the steady state ozone concentration in the liquid could be reached. The experimental results showed that the steady state ozone concentration in aqueous phase increased with the increase of gas velocity, but decreased with increasing pH or UV light intensity. A mathematical model of ozone absorption was proposed from the film theory. The decomposition rate constants of ozone were determined according to the model. It indicated that gas velocity had no effect on the rate constants. And the rate constants were also independent on pH, which was different from ozone decomposition without UV radiation due to the different decomposition mechanism. The rate constants increased with the increase of UV light intensity, which could be expressed as the following equation, k1 = 0.269 I 0.617.