Carbon materials for catalytic degradation of organic compounds in carbon-sulfide systems have received great interest for potential environmental remediation application. Either the surface oxygen functional groups or the graphite/graphene region on the carbon surface is commonly recognized as the controlling factor in mediating the reductive degradation. In this study, by introducing 21 carbon materials for catalytic degradation of nitro-aromatic compounds (NACs) in a carbon-sulfide system, we found a new mechanism that the particle size of carbon materials played a more dominant role in the reaction. This is because only the mesopores and the exterior carbon surface are accessible for the reaction. The measured double-layer capacitances of carbons could be used for indicating the accessible surface area. However, further adsorption experiments suggested that the reduction of nitrobenzene in the carbon-sulfide system might not be merely adsorption controlled. We hypothesized that the nonadsorbed NACs might be directly reduced via an outer-sphere electron transfer pathway. The influence of ionic strength and the molecular charges of NACs provided the necessary evidence. These results improve our understanding about the catalytic role of carbon materials and highlight the advantage of the smaller sized activated carbons for degradation of NACs in carbon-sulfide systems.

中文翻译：

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活性炭对硫化碳还原系统中硝基芳烃催化降解的尺寸效应

用于催化降解碳-硫化物体系中有机化合物的碳材料在潜在的环境修复应用中受到了极大的关注。碳表面上的表面氧官能团或石墨/石墨烯区域通常被认为是介导还原降解的控制因素。在这项研究中，我们通过引入 21 种碳材料在硫化碳体系中催化降解硝基芳香族化合物 (NACs)，发现了碳材料的粒径在反应中起更主导作用的新机制。这是因为只有中孔和外部碳表面可用于反应。测量的碳的双层电容可用于指示可及表面积。然而，进一步的吸附实验表明，碳-硫化物体系中硝基苯的还原可能不仅仅是吸附控制的。我们假设未吸附的 NAC 可能通过外球电子转移途径直接还原。NACs 的离子强度和分子电荷的影响提供了必要的证据。这些结果提高了我们对碳材料催化作用的理解，并突出了较小尺寸的活性炭在硫化碳系统中降解 NAC 的优势。NACs 的离子强度和分子电荷的影响提供了必要的证据。这些结果提高了我们对碳材料催化作用的理解，并突出了较小尺寸的活性炭在硫化碳系统中降解 NAC 的优势。NACs 的离子强度和分子电荷的影响提供了必要的证据。这些结果提高了我们对碳材料催化作用的理解，并突出了较小尺寸的活性炭在硫化碳系统中降解 NAC 的优势。