Mesoporous Iraqi red kaolin clay as an efficient adsorbent for methylene blue dye: Adsorption kinetic, isotherm and mechanism study

An eco-friendly and mesoporous Iraqi red kaolin clay (IRKC) was utilized as an efficient and low-cost adsorbent for the removal of methylene blue (MB) dye from aqueous environment. Various analytical techniques were used to investigate the surface area, surface morphology, material crystallinity, and fundamental functional group of the IRKC. The impact of adsorption operational parameters such as adsorbent dosage (0.02-0.20 g), solution pH (2-10), contact time (0-300 min), and initial MB dye concentrations (10-120 mg/L) were studied. The adsorption results were well described by pseudo-first order (PFO) kinetic, and adsorption isotherm was followed both Langmuir and Freundlich models. The maximum adsorption capacity (q(max)) of IRKC for MB dye was found to be 240.4 mg/g at 303 K. Thus, this work indicates that the IRKC can be applied as a natural promising adsorbent for MB dye as model of cationic dye from aqueous environment. The MB dye adsorption mechanism by IRKC can be assigned to several types of interactions such as electrostatic attractions, H-bonding interaction, and n-p interaction.