超声/Fenton法处理三氯吡啶醇钠废水工艺优化及机理初探

采用超声/Fenton技术处理三氯吡啶醇钠生产过程中产生的高浓度有机废水。通过正交试验确定超声/Fenton氧化最佳操作参数为H2O2投加量0.7 mol/L、Fe2+投加量1.39 g/L、反应时间90 min,此时COD降解率达95.3%。结果表明,Fe2+投加量是影响CODCr去除率最主要的因素。结合气相色谱-质谱联用仪检测,分析了超声/Fenton反应前后产物,初步探讨了超声/Fenton氧化法处理三氯吡啶醇钠废水的反应历程:在·OH作用下,氯苯与苯环转化为氯乙烯等小分子物质;氯乙烯发生加氢反应,进而转化为氯乙烷、氯甲烷。氯原子能够被·OH氧化为Cl·,并通过氢原子取代反应,将氯乙烯转化为1,1-二氯乙烯。

A new approach to the mechanism of sodium 3, 5, 6-richloropyridin-2-ol treatment by the ultrasonic/combined Fenton reaction and its optimization

This paper is aimed to introduce the degradation process of the 3,5,6-richloropyridin-2-ol through the ultrasonic/combined Fenton reaction so as to optimize the processing conditions.As is known,the said 3,5,6-richloropyridin-2-ol production sewage is a kind of refractory organic industrial waste water,which can be treated by way of the ultrasonic/fenton method characterized by its strong oxidizing capability,fast reaction rate and cost-effectiveness.For the treating purpose,we have to study the influential factors concerned,such as the effect of H2O2 dosage (A),Fe2 + dosage (B) and reaction time (C) on the removal of the organic matters by taking into account the advantages of the orthogonal table of L9 (34).At the same time,we have also to apply the 3 levels set for each factor and the CODCr removal rate as an evaluation index to optimize the experimental conditions.So far as we know,the optimized conditions can be determined based on the orthogonal test as follows:H2O2 dosage should be equal to 0.7 mol/L,and the Fe2 + dosage.1.36 g/L,with the reaction time being 90 minutes.And,on the whole,it is necessary to do such verification tests in three sets under the optimum conditions.As a result,we have managed to make the CODCr removal rate so high as to 95.3％,with the concentration of COD,chroma,ammonia,chloride and other indicators being far below the top emission concentration limit except for the total nitrogen.Simultaneously,we have also managed to increase the BOD5/CODCr value from 0.09 to 0.22,and the biodegradability of the sewage significantly so as to ensure the stability and reliability of the subsequent biological treatment unit faithfully.Furthermore,we have also analyzed the products before and after the reaction by means of GC-MS.Besides,in the paper,a preliminary discussion has been done over the degradation pathway of 3,5,6-richloropyridin-2-ol in the ultrasonic/combined Fenton reagent oxidation process.The results of the above investigation and experiments show that,it is possible for chlorobenzene and benzene to be converted into vinyl chloride and other smaller molecules as a consequence of · OH,whereas vinyl chloride can be subsequently transformed into chloromethane and chloroethane due to the hydrogenation reaction.The chlorine atom can be oxidized to Cl ·by · OH,and,in contrast,the vinyl chloride can be turned into 1,1-dichloroethylene by hydrogen atom substitution reaction.What is more,for the time being,the synthetic water can be used on the most of the relevant research purposes,which can be realized based on the actual production sewage both theoretically and practically.