Fabrication of Functionalized Porous Silica Nanocapsules with a Hollow Structure for High Performance of Toluene Adsorption–Desorption

Functionalized mesoporous silicas are an emerging kind of adsorbents for the removal of volatile organic compounds (VOCs). Breaking the limitations of traditional mesoporous silica, in this study, porous silica nanocapsules (PSNs) functionalized with phenyl and n-octyl groups (named as p-PSN and n-PSN, respectively) were developed for the first time. Under dry conditions, the PSNs exhibited highest dynamic adsorption capacity and desorption efficiency among the ever-reported typical adsorbents (i.e., SBA-15, KIT-6, silicalite-1, and activated carbon). Under wet conditions, the functionalized PSNs made up the defects of pure PSNs, displaying excellent hydrophobicity. The Q_WET for n-PSN and p-PSN increased by 44 and 76%, respectively, as compared with that of pure PSNs in 50% relative humidity. The Henry constant of static adsorption demonstrated that p-PSN had a better capture ability for toluene, which was owing to the π-interaction between the phenyl groups and the toluene molecules. In addition, p-PSN showed considerable stability after six consecutive dynamic adsorption–desorption cycles in 50% relative humidity.