Kinetics and Isotherm Studies on Methylene Blue Adsorption onto Ground Palm Kernel Coat

Palm kernel coat (PKC) was collected from an oil palm seed processing factory and the residual oil on the PKC was removed by saponification. The ability of the PKC to remove Methylene Blue (MB), a basic dye from waste stream, was studied by the method of continuous variation of 2 process variables: Initial MB concentration (mg/l) and PKC dosage (g/l). The amount of MB sorbed per gram of PKC (qt mg/g) increased with increasing initial MB concentration while a reverse trend was observed when the PKC dosage was increased. The experimental data were fitted into the following kinetic models: Lagergren pseudo-first order, the chemisorptions pseudo-second order, Elovich kinetic model, and the intraparticle diffusion model. It was observed that chemisorptions pseudo-second order kinetic model described the sorption process with high coefficients of determination (r2) better than any other kinetic models. The equilibrium isotherms, for the sorption of MB on PKC, were analyzed using 3 widely used isotherm models (Langmuir, Freundlich, and Temkin isotherm models). Error analysis, using the linear correlation coefficients (r2), showed that the Langmuir isotherm best fits the MB adsorption data on PKC. The monolayer coverage capacity of the PKC, obtained from the Langmuir isotherm studies, was 277.77 mg/g. Thermodynamics showed that the adsorption of MB on PKC was most favorable and spontaneous