Porous carbon fibers from low-temperature sodium amide activation for acetone adsorption

Abstract

The low energy consumption and facile activation methods are of great significance to synthesize porous carbon fibers. In this work, polyacrylonitrile-based porous carbon fiber (ACFN-X) was synthesized by sodium amide activation at the temperature ranges of 400–600 °C. The characterization of ACFN-X proves the formation of porous structure and N–O doped surface. Acetone was used as an adsorbate to explore the adsorption performance of the ACFN-X samples. The maximum acetone adsorption capacity is 4.80 mmol g−1 (at 25 °C, 18 kPa). The experimental results are well fitted by the Freundlich model, Sips model and Langmuir model to express the equilibrium adsorption, which indicates that the ACFN-X has a positive adsorption cooperativity on the acetone. Besides, the pseudo-first-order and pseudo-second-order kinetic model could well describe the kinetic processes. The rate constant k2 is mainly affected by the positive effect of the nitrogen functional groups. Moreover, the coupling roles of pore structure and functional groups on acetone adsorption performance were also explored. The results show that micropores play a crucial role in acetone adsorption. Nitrogen functional groups play a promoting role in micropores, and the addition of the pyrrolic exhibits the highest affinity with acetone molecules in the presence of oxygen functional groups. This study provides ideas an option for the preparation of porous carbon fibers as VOCs adsorption.