Nitrogen doped porous hollow carbon spheres for enhanced benzene removal

In this work, nitrogen doped hollow carbon spheres (NHCS) were synthesized via modified "silica-assistant" route and further examined as adsorbents for the removal of benzene, which is a typical volatile organic compounds (VOCs). To understand the structure and composition on benzene removal, solid carbon spheres (SCS), nitrogen doped solid carbon spheres (NSCS) and hollow carbon spheres (HCS), were also prepared for comparison. The structure and morphology characterization revealed that the resultant carbon spheres possess uniform spherical shape, abundant micropores and mesopores with solid or hollow structure and high pore volume. Combined with Raman and XPS spectra, the composition of carbon spheres was successfully tailored via introduction of nitrogen atom into carbon matrix. To present the removal performance of carbon spheres for VOCs, the dynamic adsorption behavior was evaluated. Attributed to the combined effect of hollow structure and nitrogen doping, NHCS presents remarkable dynamic adsorption performance for benzene vapor with adsorption capacity of 766 mg/g. The enhancement on desorption behaviors resulting from hollow structure of HCS is confirmed when compared with SCS. Carbon spheres exhibit good regenerability based on desorption experiment. The mechanism of enhanced adsorption performance caused by nitrogen doping is clarified as the combined action of adjustment on porous structure and composition. These results indicate that NHCS would become a promising candidate for VOCs removal. (C) 2017 Elsevier B.V. All rights reserved.