Zinc chloride–activated glycerine pitch distillate for methylene blue removal—isotherm, kinetics and thermodynamics

This work was aimed at evaluating the adsorptive properties of glycerine pitch distillate-based activated carbons by zinc chloride activation. A commercial activated carbon derived from petroleum pitch distillate was employed for comparison. Activated carbons were characterized for elemental composition, textural characteristics, and surface chemistry. The adsorption data were analyzed using isotherm and kinetic models, and thermodynamic parameters. The specific surface area of activated carbons is between 50.4 and 804 m²/g. The maximum methylene blue capacity of 368 mg/g is comparable with that of commercial activated carbon. The fitting of adsorption data suggests a monolayer coverage of dye molecules onto activated carbon via chemisorption where a cooperative mechanism of particle diffusion and film diffusion may be the controlling mechanism. The adsorption is spontaneous for potential applications in dye wastewater treatment.