Antibiotic removal by adsorption using chitosan and halloysite based nanoparticles from aqueous medium in batch stirred reactors

The halloysite- based composites were produced by using chitosan and alginate in this study. These composites were used as sorbents to remove tetracycline antibiotics from aqueous solution in batch stirred reactors. After the synthesis of the halloysite/ chitosan nanocomposites and halloysite/ alginate hydrogel beads, to investigate the crystalline structure and to compare the structures after composite formation XRD (X-Ray Diffraction), to see the surface morphology SEM (Scanning Electron Microscopy) and TEM (Transmission Electron Microscopy), to obtain the groups which is bonded chemically FTIR (Fourier Transform Infrared Spectroscopy), to observe the structural effects of temperature TGA (Thermogravimetric Analysis) and DSC (Differential Scanning Calorimeter) analyses were performed. The results of adsorption studies by using the halloysite/ chitosan composites and the halloysite/ alginate hyrogel beads were compared with the adsorption results by using the halloysite nanotubes, chitosan nanoparticles and alginate beads as a sorbent only. The maximum adsorption efficiency using halloysite nanotube as a sorbent was obtained as 73.53% at pH 5.00. The adsorption efficiency for the systems using the chitosan nanoparticles and alginate hydrogels as sorbent is very low relatively. In the systems using composite hydrogel spheres synthesized by combining halloysite nanotubes with alginate at different mass ratios, the optimum mass ratio of halloysite to alginate was determined as 3:1 and a adsorption efficiency of 73.06% at pH 2.80 was reached. In this thesis, the compliance of the tetracycline adsorption on halloysite nanotubes, halloysite/ chitosan nanocomposites and halloysite/ alginate beads to the Langmuir and Freundlich models was investigated. It was determined that the experimental data of tetracycline adsorption on halloysite nanotubes show the best fit to the Langmuir Model. On the other hand, tetracycline adsorption on halloysite/ chitosan and halloysite/ alginate sorbents was detected to be better represented by the Freundlich Model.It has been determined that tetracycline adsorption of halloysite/ chitosan nanocomposites was also compatible with the Langmuir model while tetracycline adsorption of halloysite/ alginate beads can not be represented by the Langmuir model. The fit of adsorption kinetics of tetracycline on halloysite nanotubes, halloysite/chitosan nanocomposites and halloysite/ alginate beads to pseudo first order and pseudo second order kinetic models were evaluated. The tetracycline adsorption on halloysite nanotubes and halloysite/ chitosan nanocomposites showed better fit to the pseudo second order kinetic model. On the other hand, the tetracycline adsorption on halloysite/ alginate hydrogel beads was seen to be represented by the pseudo-first order model. Keywords: halloysite nanotube, halloysite/ chitosan nanocomposite, halloysite/ alginate hydrogel beads, tetracycline.