Acid-factionalized biomass material for methylene blue dye removal: a comprehensive adsorption and mechanism study

Coconut (Cocos nucifera) shell was chemically treated with sulfuric acid (H2SO4) to produce acid- factionalized biosorbent for methylene blue (MB) dye removal from aqueous environment. Various analytical techniques were utilized to investigate the surface area, surface morphology, crystallinity, elemental composition, and functional group of the sulfuric acid-treated coconut shell (SATCS). The adsorption parameters such as adsorbent dosage (0.02-0.20 g), solution pH (3-10), contact time (0-360 min), and initial MB dye concentration (25-200 mg/L) were studied. The adsorption results were illustrated by pseudo-second order kinetic and Freundlich isotherm models. It was found that SATCS has a maximum adsorption capacity (q(max)) of 50.6 mg/g at 303 K. The adsorption mechanism of MB dye on the SATCS surface can be assigned to the various types of interactions such as electrostatic attractions, H-bonding interaction, and pi-pi interaction. This work shows SATCS as promising acid- factionalized biosorbent for removal MB dye.