Surface modification of biomass derived toluene adsorbent: Hierarchically porous characterization and heteroatom doped effect

Abstract The N–O codoped carbon materials with high specific surface areas and hierarchical porosities were synthesized by a simple dual-templating method using low-cost biomass materials. Toluene was used as a model adsorbate to explore the adsorption performance of all samples, and the sample derived from the greengrocery precursor obtained the highest specific surface area (1650 m2 g−1) and adsorption capacity (627 mg g−1). The experimental results were well fitted by the Langmuir-Freundlich and the Freundlich models, indicating a heterogeneity of the sample surface and a positive adsorption cooperativity. Moreover, the effects of physical structure and surface chemistry on the toluene adsorption performance were also explored. The results showed that the hierarchical porosity and specific surface area were the key factors to physical adsorption, while the presence of nitrogen-containing functional groups could enhance the effect of chemical adsorption significantly and the pyrrolic-N functional groups exhibited the highest affinity with toluene molecules. This study can be used to produce various kinds of low-cost biomass derived heteroatom-doped hierarchically porous carbon adsorbents.