Ionic liquid functionalization of chitosan beads for improving thermal stability and copper ions uptake from aqueous solution

Abstract Chitosan (CHI) beads modified with ionic liquids (ILs) were synthesized to remove copper ions from aqueous solution by adsorption. This paper presents the results of isotherm and kinetics for both pristine and ILs-modified CHI beads, comparing their adsorption capacity and evaluating the mechanisms involved in the batch adsorption process. Isotherm data for Cu(II) ions adsorption were fitted to Langmuir and Freundlich models, while adsorption kinetic was assessed by adjusting the data to pseudo-first order, pseudo-second order and intra-particle models. Characterization results indicate that IL functionalization promotes a significant modification on bead morphology, crystallinity and thermal stability. ILs lead to an increase in the adsorption capacity at lower Cu(II) concentrations (20 mg L −1 ), followed by the higher affinity of Cu(II) to the adsorbate. Due to the higher stability and affinity to copper ions, ILs-modified CHI beads come out as a promising strategy for developing new materials and processes with improved heavy metal uptake properties.