Effect of Polarity of Activated Carbon Surface, Solvent and Adsorbate on Adsorption of Aromatic Compounds from Liquid Phase
Effect of Polarity of Activated Carbon Surface, Solvent and Adsorbate on Adsorption of Aromatic Compounds from Liquid Phase
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DOI：
10.1248/cpb.c15-00039
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发表时间：
2015-09-01
影响因子：
1.7
通讯作者：
Imazeki, Fumio
中科院分区：
文献类型：
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作者：
Goto, Tatsuru;Amano, Yoshimasa;Imazeki, Fumio
在这项研究中，酸性官能团的碳表面上的引入和他们的去除进行了通过两种氧化方法和脱气，研究具有不同极性的芳香族化合物（苯和硝基苯）的吸附机理。对这些芳烃在水溶液和正己烷溶液中的吸附进行了实验，以获得作为起始材料的商业活性炭（BAC）、其两种类型的氧化BAC样品（0Xs）以及它们在900 ℃下的脱气样品（OGs）的吸附等温线。研究了硝基苯在水溶液中对生物活性炭、氧化物和有机玻璃的吸附和脱附动力学。结果表明，水溶液中丰富的酸性官能团显著阻碍了苯分子的吸附，而随着溶液浓度的增加，硝基苯在氧化物表面的吸附量逐渐增加，说明硝基苯由于其高的偶极矩而有利于吸附在亲水性表面上.在正己烷溶液中，由于苯与正己烷溶剂之间的亲和力很强，苯很难吸附在任何样品上。在正己烷溶液中，硝基苯在氧化石墨上的吸附量大于氧化石墨，说明硝基苯可以吸附两个吸附位点，即石墨烯层和表面酸性官能团。硝基苯在OXs上的吸附和解吸速率常数均低于BAC上的速率常数，这是由于酸性官能团对扩散的干扰。
In this study, introduction of acidic functional groups onto a carbon surface and their removal were carried out through two oxidation methods and outgassing to investigate the adsorption mechanism of aromatic compounds which have different polarity (benzene and nitrobenzene). Adsorption experiments for these aromatics in aqueous solution and n-hexane solution were conducted in order to obtain the adsorption isotherms for commercial activated carbon (BAC) as a starting material, its two types of oxidized BAC samples (0Xs), and their outgassed samples at 900 degrees C (OGs). Adsorption and desorption kinetics of nitrobenzene for the BAC, OXs and OGs in aqueous solution were also examined. The results showed that the adsorption of benzene molecules was significantly hindered by abundant acidic functional groups in aqueous solution, whereas the adsorbed amount of nitrobenzene on OXs gradually increased as the solution concentration increased, indicating that nitrobenzene can adsorb favourably on a hydrophilic surface due to its high dipole moment, in contrast to benzene. In n-hexane solution, it was difficult for benzene to adsorb on any sample owing to the high affinity between benzene and n-hexane solvent. On the other hand, adsorbed amounts of nitrobenzene on OXs were larger than those of OGs in n-hexane solution, implying that nitrobenzene can adsorb two adsorption sites, graphene layers and surface acidic functional groups. The observed adsorption and desorption rate constants of nitrobenzene on the OXs were lower than those on the BAC due to disturbance of diffusion by the acidic functional groups.