Experimental and computational investigation on the organic acid modification of porous carbon for toluene adsorption under humid conditions

Abstract

Co-existence of moisture in exhaust gas reduces significantly the adsorption capacity of porous carbon toward volatile organic compounds (VOCs). In this study, hydrophobic porous carbon (AC-MA), which is highly efficient for toluene adsorption under high-humidity conditions, was synthesized by modification with natural organic acids. It was found that the alkane groups of organic acids were all grafted onto the porous carbon to form non-polar surfaces with high hydrophobicity. In the presence of H2O moisture, the AC-MA demonstrated superior capacity and high selectivity in toluene adsorption, due to the π-π interaction, hydrophobic effect and van der Waals interaction between toluene and porous carbon surface, and could sustain its performance even after five regeneration cycles. Grand Canonical Monte Carlo simulation, supplemented with experimental verifications, showed that AC-MA was more selective for adsorbing toluene molecules than non-modified AC, which adsorbed water molecules more easily. This study provides a new and viable solution to improve the performance of porous carbon in VOC adsorption under high-humidity conditions.