Microporous activated carbon developed from KOH activated biomass waste: surface mechanistic study of methylene blue dye adsorption

In this work, sugarcane bagasse waste (SBW) was used as a lignocellulosic precursor to develop a high-surface-area activated carbon (AC) by thermal treatment of the SBW impregnated with KOH. This SBW activated carbon (SBWAC) was characterized by crystallinity, porosity, surface morphology and functional groups availability. The SBWAC exhibited Type I isotherm which corresponds to microporosity with high specific surface area of 709.3 m²/g and 6.6 nm of mean pore diameter. Further application of SBWAC as an adsorbent for methylene blue (MB) dye removal demonstrated that the adsorption process closely followed the pseudo-second order kinetic and Freundlich isotherm models. Conversely, a thermodynamic study revealed the endothermic nature and spontaneity of MB dye adsorption on SBWAC with high acquired adsorption capacity (136.5 mg/g). The MB dye adsorption onto SBWAC possibly involved electrostatic interaction, H-bonding and π-π interaction. This work demonstrates SBW as a potential lignocellulosic precursor to produce high-surface-area AC that can potentially remove more cationic dyes from the aqueous environment.