Waste Hemp Fibers (HFs) Derived Porous Carbons: Preparation, Characterization, and Potential Applications
Abstract
The main objective of the present research was to develop environmentally friendly and cost-effective porous carbon materials of improved properties from waste hemp fibers. Two different types/categories of porous carbons were prepared from hemp fibers. In one type, porous carbon materials were developed by a simple one-step method of carbonization and activation. The other type of carbon materials developed in this study were nitrogen-containing activated carbons, which were developed by introduction of nitrogen-containing functional groups on the surface of hemp fibers followed by activation and carbonization. The pore structure/distribution and surface chemistry of the prepared carbons were investigated through the analysis of BET (Brunauer-Emmett-Teller) surface area, pore size and pore volume, X-ray diffraction (XRD), scanning electron microscopy (SEM) images, high resolution transmission electron microscopy (HRTEM) images, Fourier transform-infrared (FT-IR) spectra, and Raman scattering. The carbons developed in this study were mostly mesoporous, and the BET surface area and pore volume of the carbon prepared under optimal conditions were significantly higher than those of commercially available carbon products such as granular and powder activated carbons. The potential of hemp fiber-derived carbons as adsorbents for removal of model naphthenic acids from contaminated aqueous solutions was studied, and the removal efficacy of the prepared carbons was evaluated against that of commercial granular activated carbon. The carbons prepared in this study demonstrated substantially higher efficiency than the commercial carbons for removal of model naphthenic acids from aqueous streams.