Facile synthesis of magnetic/halloysite‐based chitosan Schiff base for the efficient removal of toxic metals from aqueous solutions

Abstract A novel pyrazole‐based heterocyclic aldehyde was utilized for the preparation of a chitosan Schiff base via the condensation method, and further the chitosan‐based Schiff base was incorporated with magnetic/halloysite to form a nanocomposite. The novel functionalized material was analyzed and characterized employing a range of analytical techniques. The nanocomposite exhibited a significant increase in surface area and porosity, which showed enhanced adsorptive ability, and the adsorptive process was screened at various concentrations varying from 20 to 100 ppm. The adsorptive nature towards metal ions is brought about by the electrostatic interaction between modified chitosan and metal ions. Under the best conditions, an increase in the uptake capacity of 89.285 and 163.934 mg g −1 for Cu(II) and Cr(VI) was observed. The equilibrium adsorption capacity obtained followed the Langmuir model with a monolayer coverage process, and the phenomenon tends to follow second‐order kinetics. The thermodynamics of the sample were spontaneous in nature, and the heat content of the system was determined to be endothermic. Desorption studies indicated successful regeneration of the material using suitable stripping solutions. The modified chitosan with high removal efficiency and reusability makes it a promising bioadsorbent material for the wastewater purification process. © 2026 Society of Chemical Industry.