Remarkable performance of N-doped carbonization modified MIL-101 for low-concentration benzene adsorption

Abstract

As a common volatile organic compound (VOC) species emitted from industrial production, benzene poses a severe threat to human health. Due to its ultra-high specific surface area and developed mesoporous structure, MIL-101 based metal–organic framework (MOF) materials are widely used in VOCs adsorption. However, MIL-101 has a poor ability to adsorb non-polar benzene due to its polar ligands and metal nodes. Herein, we presented a simple strategy of carbonization and nitrogen doping to modify MIL-101. The effect of various surface physicochemical properties of modified MIL-101 on its adsorptive capacity was thoroughly evaluated. The interaction mechanism between activated sites of modified MIL-101 and benzene was also deeply explored using density functional theory (DFT) calculation. The results showed that modified MIL-101 featured graphite skeletons doped with different N-containing functional groups. The adsorptive capacity of MCN-800 increased by 100% compared with that of pristine MIL-101, owing to the largest mesoporous volume and the greatest number of the pyridinic-N moiety. Moreover, both experimental and theoretical results proved that N-containing functional groups had a strong interaction with benzene through π-π interaction and N-H hydrogen bond, and pyridinic-N displayed a stronger interaction than pyrrolic-N and graphite-N. This study provides a valuable synthesis strategy of functionalized MOF adsorbents for the removal of low-concentration benzene pollution.