Preparing high surface area porous carbon from biomass by carbonization in a molten salt medium

Abstract

The preparation of porous carbon with a high surface area from biomass is important for its practical application. In the present study, peanut shells were transformed into porous carbon through a simple ZnCl₂-molten salt synthesis (MSS) process. The carbonization and two activation processes could be completed together in one step, and carbonization time and temperature were reduced significantly because of the favorable flux environment for carbonization provided by the molten ZnCl₂ medium. The properties of peanut shell-activated carbon (PAC) were characterized by XRD, TG-DSC, SEM, TEM, FT-IR spectra and BET isotherms. The results showed that the as-prepared PAC was amorphous and had a hierarchical porous structure with a high surface area of 1642 m² g⁻¹. Some functional groups were retained on the surface of the PAC and provided more adsorption sites. When the prepared PAC was used as an adsorbent to remove methylene blue (MB) dye from an aqueous solution, it exhibited superior adsorption capacity as high as 876 mg g⁻¹, which indicates that the PAC from peanut shells can be used as a low-cost and effective adsorbent for water purification.