Engineering surface functional groups on mesoporous silica: towards a humidity-resistant hydrophobic adsorbent

Practical volatile organic compound (VOC) adsorption requires the functional materials to work in humid conditions, whereas most proposed materials fail to overcome this challenge. We report a facile thermal treatment approach to create an organic functional group-enriched and hydroxyl group-limited mesoporous silica, that exhibits dramatically improved humidity resistance and toluene adsorption capacity. Fundamental adsorption behaviors of the materials were investigated both statically and dynamically to distill the functional mechanisms of the performance enhancement. In particular, the results of adsorption heat demonstrated their hydrophobicity and strong affinity to toluene, and dynamic adsorption tests illustrated a higher adsorption selectivity for toluene (with 1.39-1.84 times the hydrophobicity values of Q(wet)/Q(dry) (76.4-71.5%) compared with pristine silica) and reusability, which were both attributed to the durable and stable surface hydrophobicity.