Adsorption of tetracycline antibiotics from an aqueous solution onto graphene oxide/calcium alginate composite fibers

In this study, we report the preparation of a novel environmentally friendly and highly efficient adsorbent, graphene oxide/calcium alginate (GO/CA) composite fibers, via a freeze-drying method using calcium chloride as a cross-linking reagent between graphene oxide and sodium alginate. The maximum tetracycline adsorption capacity of the GO/CA composite fibers predicted by the Langmuir model reached 131.6 mg g(-1). The adsorption properties of tetracycline onto the fibers were investigated through several parameters including the solution pH, the adsorbent dose, the initial concentration of tetracycline, and the agitation time. The Langmuir and Freundlich adsorption isotherms were used to investigate the adsorption equilibrium. The kinetics of the adsorption process was predicted using the pseudo-first-order and pseudo-second-order kinetic equations. Furthermore, the mechanism of adsorption was investigated, and it was found that the hydrogen bonding and p-p interaction should serve as predominant contributions to the significantly enhanced adsorption capability.