Metallic ion leaching from heterogeneous catalysts: an overlooked effect in the study of catalytic ozonation processes
Metallic ion leaching from heterogeneous catalysts: an overlooked effect in the study of catalytic ozonation processes
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DOI：
10.1039/c7ew00273d
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发表时间：
2017-10
期刊：
影响因子：
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通讯作者：
Wenwen Yang;B. Vogler;Y. Lei;Tingting Wu
中科院分区：
文献类型：
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作者：
Wenwen Yang;B. Vogler;Y. Lei;Tingting Wu
近年来，多相催化臭氧氧化降解难降解有机水污染物和矿化的研究日益受到重视。与均相催化剂相比，多相催化剂的一个重要优点是可以很容易地从处理后的水中分离出来，使该工艺在经济上是可行的。虽然许多研究都集中在基于金属氧化物的催化臭氧氧化的开发和评价上，但有时忽略了金属离子的可能浸出以及随后对污染物降解的影响。在这里，我们考察了几种固体催化剂上的金属浸出情况，并进一步考察了在连续臭氧氧化过程中浸出的金属离子对两种模型化合物(草酸盐和硝基苯)矿化的影响。在实验室条件下，对市售催化剂和湿化学法制备的催化剂进行了金属离子浸出实验。水基质已被证明在金属浸出中起着重要作用。浸出的金属离子具有明显的均相催化作用。通过·OH与铜(II)/草酸盐反应生成不稳定的铜(III)/草酸盐络合物的机理，解释了实验观察结果。我们的结果表明，在催化臭氧氧化有机污染物的过程中，必须仔细检查固体催化剂的稳定性和浸出离子的影响。通过这项研究，我们强调了在研究界内评估和报告水/废水处理中多相催化剂性能的严格、公认的协议的重要性。
Heterogeneous catalytic ozonation has been increasingly studied for the degradation and mineralization of refractory organic water pollutants in recent years. Compared with homogeneous catalysts, an important advantage of heterogeneous catalysts is that they can be easily separated from the treated water, making the process economically viable. While many studies have focused on the development and evaluation of metal oxide-based catalytic ozonation, possible leaching of metal ions and the subsequent effect on the contaminants' degradation are sometimes overlooked. Here, we examined metal leaching from several solid catalysts and further investigated the influence of the leached metal ions on the mineralization of two model compounds (oxalate and nitrobenzene) during continuous ozonation. Metallic ion leaching was observed from both commercially-available catalysts and catalysts prepared via wet-chemistry methods in the lab. The water matrix has been demonstrated to play an important role in metal leaching. The homogeneous catalytic effect resulting from the leached metal ions was found to be significant. A mechanism involving the formation of an unstable Cu(III)/oxalate complex through the reaction between ˙OH and Cu(II)/oxalate was proposed to explain the experimental observations. Our results indicate that the stability of the solid catalysts and the effects of the leached ions must be carefully examined during the catalytic ozonation of organic contaminants. Through this study we highlight the importance of rigorous, accepted protocols for evaluating and reporting heterogeneous catalyst performance in water/wastewater treatment within the research community.