Epoxidized Natural Rubber-Derived Carbon Nanofibers with Tunable Microporosity for Efficient CO2 Capture

Abstract

This study developed porous carbon nanofibers (CNFs) to enhance the carbon dioxide (CO2) uptake capacity and adsorption kinetics. The CNFs were fabricated via electrospinning of a polymeric precursor consisting of epoxidized natural rubber (ENR) with polyacrylonitrile (PAN), followed by subsequent thermal treatment. ENR contents ranging from 10 to 80 wt % were incorporated into PAN to investigate their effects on the textural properties and porosity development of CNFs produced by electrospinning. The influences of textural characteristics, physical activation, and adsorption kinetics on the CO2 uptake capacity were systematically investigated. Among the prepared samples, 20ENR-CNF exhibited the highest CO2 uptake capacity, achieving 3.53 mmol g–1 for the as-prepared sample and 4.35 mmol g–1 after activation at 273 K under 1 bar. This enhanced performance is attributed to its high porosity and favorable isosteric heat of adsorption (28.18 kJ mol–1). Kinetic studies demonstrated that varying the ENR content significantly affected both the CO2 uptake capacity and adsorption rate, with intraparticle diffusion identified as a key controlling mechanism. ENR incorporation played a crucial role in tailoring the pore structure within the CNF matrix, thereby improving the CO2 adsorption performance. A pressure swing adsorption test conducted over five cycles confirmed the excellent recyclability of the activated 20ENR-CNF sample. Furthermore, increasing the ENR content was found to significantly enhance the CO2 adsorption rate.