Investigation of tetracycline removal from aqueous solutions using halloysite/chitosan nanocomposites and halloysite nanotubes/alginate hydrogel beads

Abstract

In this study, halloysite nanotube-based composites were synthesized using chitosan and alginate biopolymers. The removal of tetracycline from aqueous solutions containing the tetracycline antibiotic with these composites was examined in batch-stirred vessels.The characterization of halloysite/chitosan nanocomposites and alginate hydrogel beads filled with halloysite nanotubes was performed using FTIR, BET, XRD and compared with their pure states. To examine the surface morphology, the SEM images of alginate hydrogel beads filled with halloysite nanotubes and TEM images of halloysite/chitosan nanocomposites were obtained.The tetracycline adsorption of halloysite/chitosan nanocomposites and halloysite/alginate hydrogel beads was investigated as a function of the medium pH, initial tetracycline concentration, the amount of sorbent, and the ratio of the components forming the composite to each other by mass. The tetracycline adsorption capacity and efficiency of the composites were compared with the adsorption systems in which pure halloysite nanotubes, chitosan nanoparticles and alginate beads were used as a sorbent alone. The fit of tetracycline adsorption of halloysite nanotubes, halloysite/chitosan nanocomposites, and halloysite/alginate hydrogel beads to the Langmuir and Freundlich adsorption models was investigated. To evaluate adsorption kinetics of tetracycline on halloysite based nanocomposites, the fit to the pseudo-first-order kinetic model and pseudo-second-order kinetic model was investigated.The removal of tetracyclines in different chemical forms from medical wastewater in a wide pH range can be ensured by using halloysite nanotubes alone or in composite forms. Halloysite-based composite structures have been shown to be effective in the removal of tetracyclines by the adsorption method.