Zaror C, Segura C, Mansilla H, Mondaca M A, González P
Chemical Engineering Department, University of Concepcion, Correo 3, Concepción, Chile.
Water Sci Technol. 2008;58(1):259-65. doi: 10.2166/wst.2008.661.
This paper presents experimental results on the effect of temperature on the rate of Imidacloprid removal from waste water using homogeneous photo-Fenton processes. Experiments were conducted in a 2 L photo reactor set at 15-42 degrees C, initial concentrations in the range of 10 to 40 mg L(-1) Fe(II) and 100-450 mg L(-1) H(2)O(2); 30 150 min processing times. Initial H(2)O(2) concentration determined the extent of the oxidation process, whereas iron concentration played a key role in the process kinetics. Homogeneous photo-Fenton showed a fast initial reaction leading to 50% Imidacloprid degradation after less than 1 min of treatment, followed by a slower process until full removal was achieved. Rapid Fe(II) oxidation to Fe(III) seems responsible for the initial Imidacloprid removal. Imidacloprid removal fitted well a pseudo-first order kinetic scheme, with apparent activation energy of approximately 31.6 kJ/mole. Untreated Imidacloprid samples showed significant acute toxicity to Daphnia magna and genotoxic effects on Bacillus subtilis. Acute toxicity and genotoxicity remained detectable even after complete pesticide removal, showing that toxic by-products were present. The design and operation of photo Fenton processes should focus on toxicity removal rather than on specific target pollutants.
本文介绍了温度对采用均相光芬顿法从废水中去除吡虫啉速率的影响的实验结果。实验在一个2升的光反应器中进行，温度设定为15至42摄氏度，初始浓度范围为10至40毫克/升的Fe(II)和100至450毫克/升的H₂O₂；处理时间为30至150分钟。初始H₂O₂浓度决定了氧化过程的程度，而铁浓度在过程动力学中起关键作用。均相光芬顿法显示出快速的初始反应，处理不到1分钟后吡虫啉降解50%，随后是一个较慢的过程，直至完全去除。Fe(II)快速氧化为Fe(III)似乎是初始去除吡虫啉的原因。吡虫啉的去除很好地符合拟一级动力学方案，表观活化能约为31.6千焦/摩尔。未经处理的吡虫啉样品对大型溞显示出显著的急性毒性，并对枯草芽孢杆菌有遗传毒性作用。即使在农药完全去除后，急性毒性和遗传毒性仍然可以检测到，表明存在有毒副产物。光芬顿法的设计和操作应侧重于去除毒性，而不是特定的目标污染物。
