Adsorption of Cationic Red X-GRL from Aqueous Solutions by Graphene: Equilibrium, Kinetics and Thermodynamics Study

Graphene was prepared and used as an adsorbent for removal of cationic red X-GRL from aqueous solutions. The physico-chemical properties of graphene were characterized by the transmission electron microscope (TEM), the Brunauer–Emmett–Teller (BET) specific surface area measurement, atomic force microscope (AFM), and Raman microscope. The adsorption properties of cationic red X-GRL onto graphene were studied as a function of pH, adsorbent dosage, contact time, and temperature. Kinetic data were well fitted by a pseudo second-order model. Langmuir and Freundlich adsorption models were applied to describe the isotherms and isotherm constants. Equilibrium data agreed very well with the Langmuir model. Thermodynamic studies showed that the adsorption was a spontaneous and endothermic process