Zaror C, Carrasco V, Perez L, Soto G, Mondaca M A, Mansilla H
Forest Products Laboratory, Chemical Engineering Department, University of Concepción, PO Box 53-C, Correo 3, Concepción, Chile.
Water Sci Technol. 2001;43(2):321-6.
The presence of toxic aromatic organic compounds in industrial wastewater affects the efficiency of conventional biological treatment. The oxidizing power of ozone represents an interesting pretreatment to reduce toxicity and increase biodegradability. At low pH, ozone is known to attack electron-rich structures by direct electrophilic reactions which open aromatic rings, and generate smaller oxidized compounds. This paper reports experimental results on kinetic and toxicity aspects of ozone direct reactions with 1,2-dihydrobenzene. This toxic compound is frequently found in cellulose bleaching effluents. Although the reaction pathway is rather complex, 4-carbon compounds, such as maleic acid, are readily formed during the first stage of ozonation. These 4-carbon compounds are further oxidized to form smaller molecules (mostly 2-carbon, such as oxalic acid). The apparent kinetics of 1,2-dihydrobenzene follows a second order law, with a rate constant around 0.36 (dm3 mmol-1s-1), at pH 2 and 20 degrees C. Results show that the BOD:COD ratio increase five-fold as ozonation progresses. Furthermore, the mutagenicity of 1,2-dihydrobenzene totally disappears as the aromatic compound is destroyed by ozonation.
工业废水中有毒芳香族有机化合物的存在会影响传统生物处理的效率。臭氧的氧化能力是一种有趣的预处理方法，可降低毒性并提高生物降解性。在低pH值下，已知臭氧会通过直接亲电反应攻击富电子结构，打开芳香环，并生成较小的氧化化合物。本文报道了臭氧与1,2 - 二氢苯直接反应的动力学和毒性方面的实验结果。这种有毒化合物经常出现在纤维素漂白废水中。尽管反应途径相当复杂，但在臭氧化的第一阶段很容易形成4 - 碳化合物，如马来酸。这些4 - 碳化合物进一步氧化形成较小的分子（主要是2 - 碳，如草酸）。在pH值为2和20摄氏度时，1,2 - 二氢苯的表观动力学遵循二级定律，速率常数约为0.36（dm³ mmol⁻¹ s⁻¹）。结果表明，随着臭氧化的进行，生化需氧量与化学需氧量的比值增加了五倍。此外，随着芳香族化合物被臭氧化破坏，1,2 - 二氢苯的致突变性完全消失。
