Synthesis and characterization of magnetic halloysite-chitosan nanocomposites: use in the removal of methylene blue in wastewaters

Magnetic halloysite-chitosan (MHNT-CTN) nanocomposites were synthesized by turning magnetic halloysite nanotubes (MHNTs) into nanocomposites using biopolymeric chitosan (CTN). The magnetic properties of pure halloysite nanotubes (HNTs) were achieved using the co-precipitation method, and MHNTs were synthesized. The characterization of the MHNT-CTN nanocomposite and the pure states of the components forming the nanocomposite was performed by FTIR, TGA, TEM, and VSM. Methylene blue (MB) adsorption on MHNT-CTN nanocomposites was investigated as a function of medium pH, the mass ratio of the components forming the nanocomposite material, and the initial MB concentration. The optimum conditions for MB adsorption on MHNT-CTN were determined as pH 8.0, in a solution volume of 25 mL, 25 mg MHNT-CTN, and the MHNT-to-CTN mass ratio of 2:1. The highest adsorption efficiency for MB adsorption on MHNT2-CTN1 was reached at an initial MB concentration of 20 mg/L, and it was found to be 83.9%. The adsorption equilibrium data obtained from the studies on MB adsorption on MHNT-CTN were used to investigate compatibility with the Langmuir, Freundlich, and Redlich-Peterson adsorption models. It was found out that the MB adsorption kinetics was compatible with the pseudo-second-order model.