Isotherm, kinetics and thermodynamics of methylene blue adsorption onto surface-modified Ikpobia clay

Abstract The need for water preservation, restoration and treatment has become very pertinent to address the united nation sustainable development goal. In this study, the isotherm, kinetics and thermodynamics of methylene blue adsorption from aqueous solution using surface modified Ikpobia clay was carried out. The clay samples were characterized for physicochemical and adsorptive properties. Batch adsorption was performed by varying the solution pH (pH 2–11), concentration (1–400 mg/L), adsorbent dosage (10–100 mg), temperature (24–75 °C) and contact time (5–1500 min). The refined clay (RC) exhibits a better performance at slightly acidic solution. Its surface functional groups and crystallinity suggested the presence of Si–O stretching and Al–OH bending. Its textural properties with surface area of 236 m 2 /g offers a maximum adsorption of 53.5 mg/g. The Sips and pseudo-second order models fitted well with the adsorption isotherm and kinetic data, respectively, suggesting monolayer accumulation of methylene blue onto heterogeneous surface and the possibility of strong chemical bonding. The thermodynamic parameters suggested that the adsorption of dye onto Ikpobia clay is feasible and spontaneous, and placed it as a credible adsorbent candidate for effective cationic pollutants removal from wastewater.