Preparation, surface functionalization, and characterization of carbon micro fibers for adsorption applications

Abstract

In this study, the phenolic resin and viscose rayon precursor-based activated carbon fibers (ACFs) were prepared by carbonization and steam-activation. Prepared ACFs were surface-functionalized by hydrogen peroxide and applied as adsorbents in environmental remediation applications. Carbonization and activation conditions (temperature, time, and heating rate) were varied to prepare ACFs of different specific surface area and pore size distribution. At the activation temperature of 900°C, the specific surface area was found to be maximum (∼1,700 m²/g for the phenolic resin precursor- and ∼2,300 m²/g for the viscose rayon precursor-based ACFs). However, former precursor-based ACFs contained mostly micropores, whereas the latter contained both micropores and mesopores. Adsorption of methylene blue, the reagent used as a test adsorbate molecule, was found to be dependent on the surface area, pore volume, and pore size distribution of the prepared ACFs, and also on the surface oxygen functional groups incorporated therein. These surface characteristics were found to be controlled by carbonization and activation conditions. Rayon precursor-based ACFs were found to be superior to the phenolic resin-based ACFs for adsorbing methylene blue from aqueous solution, with ∼646 mg/g of the equilibrium ions loading observed in the former, in comparison to ∼540 mg/g in the latter.