In recent years, CaO has been frequently used as a substitute for HO to address the limitations of HO. However, commercially available CaO are facing the shortcomings of low purity and limited preparation conditions. Oyster shells can provide superior and abundant biomass calcium element with low cost for developing CaO. In this work, highly purified CaO functional biomaterials were prepared via a facile approach derived from waste oyster shells, which were applied in a Fenton-like system to remove organic pollutants. Experimental results indicated that the oyster shells-derived CaO with 100% purity exhibited a greatly enhanced catalytic performance compared with other CaO materials in Fenton-like catalytic degradation of organic pollutants, which can be completely removed within 60 s. The high purity of CaO would facilitate the release of HO during the Fenton-like catalytic reaction and promote the generation of more active species to oxidize pollutants. Besides, the abundant trace metal elements originated from oyster shells can further motivate the Fenton-like reaction and accelerate the degradation of pollutants, endowing oyster shells-derived CaO an excellent catalytic activity. Furthermore, the Fenton-like catalytic mechanism was proposed on basis of tests of radicals trapping and electron spin resonance, validating the vital roles of ⋅OH, ⋅O and O generated throughout the reaction process. This work not only provides a novel and low-cost approach to exploit CaO with highly efficient catalytic ability, but also realizes the effective resource utilization of waste shells.

中文翻译：

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变废为宝：基于类芬顿系统，从牡蛎壳中轻松制备 CaO2，用于高效降解有机污染物

近年来，CaO 经常被用作 H2O 的替代品，以解决 H2O 的局限性。然而，市售CaO存在纯度低、制备条件有限的缺点。牡蛎壳可为CaO的开发提供优质、丰富的生物质钙元素，且成本低廉。在这项工作中，通过从废牡蛎壳中提取的简便方法制备了高纯度的CaO功能生物材料，并将其应用于类芬顿系统中以去除有机污染物。实验结果表明，100%纯度的牡蛎壳CaO在类Fenton催化降解有机污染物方面表现出比其他CaO材料大大增强的催化性能，可在60 s内完全去除。高纯度的CaO有利于类芬顿催化反应过程中H2O的释放，并促进产生更多活性物质来氧化污染物。此外，牡蛎壳中丰富的微量金属元素可以进一步激发类芬顿反应，加速污染物的降解，赋予牡蛎壳CaO优异的催化活性。此外，基于自由基捕获和电子自旋共振测试，提出了类芬顿催化机理，验证了整个反应过程中生成的·OH、·O和O的重要作用。该工作不仅为开发具有高效催化能力的CaO提供了一种新颖、低成本的途径，而且实现了废贝壳的有效资源化利用。