Yu Li, Zhang Pei-Long, Hou Jia-Cai, Pang Li-Fei, Li Yue, Jia Shou-Hua
College of Chemistry and Material Science, Shandong Agricultural University, Tai'an 271018, China.
Huan Jing Ke Xue. 2013 Jun;34(6):2210-7.
The rate constants for the reaction of higher concentrations of DMP with ozone and hydroxyl radical (*OH) were determined by competition kinetics method, in which nitrobenzene (NB) was selected as the reference organic compound. The effects of *OH inhibitor tert-butyl alcohol, pH and a variety of ions on the degradation of DMP were discussed. Experimental results showed that the degradation of DMP by ozonation followed pseudo-first-order kinetics. The rate constants of DMP with ozone and *OH were (0.064 +/- 0.014) L x (mol x s)(-1) and 3.59 x 10(9) L x (mol x s)(-1), respectively. The system pH decreased due to the carboxylic acids intermediates generated by ozonation at initial pH of 6.08 and 9.07, but the system pH was stabilized in strong alkali or acidic solution. A large number of intermediates resulted in the removal rate of COD lagging behind the degradation efficiency of DMP, and part of the intermediates were difficult to be mineralized. The reaction of DMP with *OH was not inhibited by lower concentrations of tert-butyl alcohol. But the reaction was inhibited when the concentration of tert-butyl alcohol was 90.21 times as high as that of DMP, and the degradation efficiency of DMP decreased from 98.7% to 8.8%. The degradation efficiency of DMP was higher with phosphate buffer solution for pH adjustment than NaOH/H2SO4 solution. Low concentrations of cations and anions had no effects on the degradation efficiency of DMP. High concentrations of SO4(2-), NO3(-) and HPO4(2-) had no remarkable effects on ozonation. But high concentrations of Cl(-) and HCO3(-) inhibited the degradation and the inhibitory effect of HCO3(-) was stronger than Cl(-). The degradation efficiency of DMP was only 50.5% and 26.2%, respectively, after 40 min under 7 097 mg x L(-1) of Cl(-) and 6 093 mg x L(-1) of HCO3(-).
采用竞争动力学方法，以硝基苯（NB）作为参考有机化合物，测定了较高浓度邻苯二甲酸二甲酯（DMP）与臭氧和羟基自由基（·OH）反应的速率常数。探讨了·OH抑制剂叔丁醇、pH值及多种离子对DMP降解的影响。实验结果表明，臭氧氧化DMP的过程遵循准一级动力学。DMP与臭氧和·OH的反应速率常数分别为(0.064±0.014) L·(mol·s)-1和3.59×109 L·(mol·s)-1。在初始pH值为6.08和9.07时，由于臭氧氧化产生的羧酸中间体，体系pH值下降，但在强碱性或酸性溶液中体系pH值稳定。大量中间体导致化学需氧量（COD）去除率滞后于DMP的降解效率，且部分中间体难以矿化。较低浓度的叔丁醇对DMP与·OH的反应无抑制作用。但当叔丁醇浓度为DMP浓度的90.21倍时，反应受到抑制，DMP的降解效率从98.7%降至8.8%。用磷酸盐缓冲溶液调节pH值时DMP的降解效率高于用NaOH/H2SO4溶液。低浓度的阳离子和阴离子对DMP的降解效率无影响。高浓度的SO42-、NO3-和HPO离子对臭氧氧化无显著影响。但高浓度的Cl-和HCO3-抑制降解，且HCO3-的抑制作用强于Cl-。在7097 mg·L-1的Cl-和6093 mg·L-1的HCO3-存在下，40 min后DMP的降解效率分别仅为50.5%和26.2%。
