Preparation of loofah vine-based hierarchical porous activated carbon for methylene blue adsorption

A loofah vine-derived activated carbon (LVAC) with hierarchical porous structure is reported for the first time. It was prepared from the natural material by potassium hydroxide (KOH) and carbon dioxide (CO2) activation. The LVAC has been characterized by SEM-EDAX, FTIR, and nitrogen sorption. The results show that the LVAC has a large specific surface area (904.6 m(2)/g) and hierarchical porosity (micropores, mesopores, and macropores). The LVAC was used as an adsorbent to adsorb methylene blue, and the maximum adsorption capacity from the Langmuir model (q(max)) was 515.46 mg/g, which was achieved at a fast rate. The high adsorption capacity and fast adsorption rate are determined by the pore structure. Macropores provide fast channels for diffusion of the adsorbate. Mesopores serve as both fast channels and adsorption surfaces. Micropores provide a high surface area for adsorption. These findings suggest that loofah vine may be an inexpensive precursor source of activated carbon, and the obtained LVAC shows considerable potential for the removal of dyes from wastewater.