Decomposition of 2-chlorophenol employing goethite as Fenton catalyst. I. Proposal of a feasible, combined reaction scheme of heterogeneous and homogeneous reactions
Decomposition of 2-chlorophenol employing goethite as Fenton catalyst. I. Proposal of a feasible, combined reaction scheme of heterogeneous and homogeneous reactions
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DOI：
10.1016/j.apcatb.2009.12.005
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发表时间：
2010-03-12
影响因子：
22.1
通讯作者：
Cassano, Alberto E.
中科院分区：
文献类型：
--
作者：
Ortiz de la Plata, Guadalupe B.;Alfano, Orlando M.;Cassano, Alberto E.
以针铁矿为催化剂，在pH = 3的条件下，采用非均相芬顿反应降解2-氯苯酚。研究的目的是获得一个可行的动力学表达式，适合发展的动力学模型，放大的目的。在现有文献中已经描述了反应的几个方面，但目前还没有对整个反应行为的合理表示。为了对整个观察到的性能提供更全面和可能的解释，进行了一组实验，系统地改变了所有重要的变量。该提案认为，该反应本质上是与一个典型的均相芬顿反应相关联的四个非均相过程的组合。三个表面反应解释了一个非常小的铁浸出介质中的质子诱导的溶解，还原溶解反应和非还原铁释放所产生的检测2-CP化学分解副产物，特别是，氯氢醌（CIHQ）和草酸（OxA）。在反应的最后阶段，在大部分2-CP已经降解之后，通过参与第三表面反应的OxA的出现，溶液中的铁浓度可以进一步增加。第四种多相反应使高催化剂负载下不寻常的过氧化氢消耗合理化。在均相反应期间，CIHQ和CIBQ的存在产生Fe 3 + -> Fe 2+转化的均相自催化有益增强。因此，酚类衍生物在混合物中或作为反应副产物的存在产生反应速率的有益提高。需要非常低的铁浸出来产生均相芬顿反应的开始，这被证明是强烈依赖于反应温度。所有的实验结果都用一套19步可行的反应方案满意地描述了。该方法可用于处理含有酚类衍生物的污染物的废水，只要铁浸出保持在可容忍的限度内。(C)2009爱思唯尔有限公司版权所有。
A study has been conducted on the decomposition of 2-chlorophenol (2-CP) applying a heterogeneous Fenton reaction using goethite as catalyst at pH 3. The research was aimed at obtaining a workable kinetic expression apt for developing a kinetic model for scaling up purposes. Several aspects of the reaction have been described in the available literature but, for the moment, without a reasonable representation of the entire reaction behavior. In order to provide a more comprehensive and probable explanation of the whole observed performance, a set of experiments was carried out varying systematically all the significant variables. The proposal considers that the reaction is essentially a combination of four heterogeneous processes associated with one typical homogeneous Fenton reaction. Three of the surface reactions explain a very small iron leaching to the medium by a proton induced solubilization, a reductive dissolution reaction and a non-reductive iron release produced by detected 2-CP chemical decomposition byproducts, particularly, chlorohydroquinone (CIHQ) and oxalic acid (OxA). Iron concentration in the solution may be further increased in the final stages of the reaction after most of the 2-CP has been degraded, by the appearance of OxA that takes part in a third surface reaction. The fourth heterogeneous reaction rationalizes the unusual hydrogen peroxide consumption at high catalyst loadings. During the homogeneous reaction, the presence of CIHQ and CIBQ produces a homogeneous autocatalytic beneficial enhancement of the Fe3+ -> Fe2+ transformation. Consequently, the existence of phenolic derivatives either in the mixture or as reaction byproducts produces a beneficial enhancement of the reaction rate. Very low iron leaching is required to produce the onset of the homogeneous Fenton reaction, which was shown to be strongly dependent upon the reaction temperature. All the experimental findings were satisfactorily described by a set of 19-step feasible reaction scheme. The process could be useful for the treatment of wastewaters containing pollutants with phenolic derivatives, as long as iron leaching remains within tolerable limits. (C) 2009 Elsevier B.V. All rights reserved.