Synthesis and characterization of γ-cyclodextrin-graphene oxide nanocomposite: Sorption, kinetics, thermodynamics and simulation studies of tetracycline and chlortetracycline antibiotics removal in water

Abstract

γ-Cyclodextrin-graphene oxide nanocomposite was synthesized and characterized for sorption, kinetics, thermodynamics, and simulation studies of tetracycline and chlortetracycline antibiotics removal from water. The optimized sorption parameters were 400 mg/L concentration, 30 min contact time, pH 8.0, dose 1.0 g/L and 25 °C temperature. The sorption followed Langmuir, Temkin, and D-Rs models. The maximum removals of tetracycline and chlortetracycline were 91.25 and 93.75% respectively, with a variation of percentage removal at different pHs ranges [355.0 (88.75%), 360.0 (90.0%) and 365.0 mg/g (91.25%) for tetracycline and 365.0 (91.25%), 370.0 (92.5%) and 375.0 mg/g (93.75%) chlortetracycline]. The sorption followed pseudo-second kinetic order reaction and liquid film diffusion kinetic model. The positive values of entropy (12.043 & 12.842 kJ/mol.K) and negative values of enthalpy (-0.944 & −1.113 kJ/mol) and free energy (-14.60 to −13.55 kJ/mol) confirmed the spontaneous sorption at all temperatures. The simulation results agreed with the sorption results. Also, the modeling was used to ascertain the supramolecular mechanism, which involved hydrogen bonding and π-π interactions.