Chu W, Chan K H, Graham N J D
Department of Civil and Structural Engineering, Research Centre for Environmental Technology and Management, The Hong Kong Polytechnic University, Hunghom, Kowloon, Hong Kong.
Chemosphere. 2006 Aug;64(6):931-6. doi: 10.1016/j.chemosphere.2006.01.028. Epub 2006 Feb 20.
In this study, the degradation of atrazine (ATZ) by ozone (O3) oxidation and its associated processes (i.e. UV, UV/O3) in the presence and absence of surfactant was investigated and compared. A non-ionic surfactant, Brij 35, was selected. It was found that the presence of a low concentration of surfactant could improve the removal of ATZ by increasing the dissolution of ozone and the indirect generation of hydroxyl radicals. The saturated ozone level and the reaction rate constants were increased with increasing the concentration of surfactant and then decreased at higher surfactant doses at pH level of 2.5. A similar trend was observed at pH level of 7.0 in the presence of bicarbonate ion, because it is capable of deactivating the hydroxyl radicals generating at higher pH level. However, when the radical reactions become dominant in the ozonation (at pH 7.0 without bicarbonate), the saturated ozone level was higher than that with bicarbonate and the kinetic rate constants were increased first and levelled off with increasing of the dose of surfactant. Through the examining of a proposed unit performance index, the low concentration of surfactant is surely beneficial to the ozonation process. Besides, the direct photolysis and photo-assisted ozonation were compared to the ozonation. A significant enhancement on the decay rate of ATZ was resulted exclusively by adding the surfactant. An enhancement index for quantifying the improvement of the various processes was developed.
本研究考察并比较了在有无表面活性剂存在的情况下，臭氧（O₃）氧化及其相关过程（即紫外光、紫外光/臭氧）对莠去津（ATZ）的降解情况。选用了一种非离子表面活性剂Brij 35。结果发现，低浓度表面活性剂的存在可通过增加臭氧的溶解以及间接产生羟基自由基来提高莠去津的去除率。在pH值为2.5时，饱和臭氧水平和反应速率常数随表面活性剂浓度的增加而升高，然后在表面活性剂剂量较高时降低。在pH值为7.0且存在碳酸氢根离子的情况下观察到类似趋势，因为它能够使在较高pH值下产生的羟基自由基失活。然而，当自由基反应在臭氧化过程中占主导地位时（在pH值为7.0且无碳酸氢根的情况下），饱和臭氧水平高于有碳酸氢根时的情况，动力学速率常数先增加，然后随着表面活性剂剂量的增加趋于平稳。通过考察一个提出的单元性能指标，低浓度表面活性剂确实有利于臭氧化过程。此外，还将直接光解和光助臭氧化与臭氧化进行了比较。仅通过添加表面活性剂就显著提高了莠去津的衰减速率。开发了一个用于量化各种过程改进的增强指数。
