Functionalization of carbon nanotubes with chitosan based on MALI multicomponent reaction for Cu2+ removal.

In this work, we reported a novel "one-pot" strategy for preparation of chitosan-coated carbon nanotubes (CNTs) composites via a combination of Diels-Alder (DA) reaction and mercaptoacetic acid locking imine (MALI) reaction for the first time. To evaluate the adsorption characteristics, the as-prepared samples were applied to remove copper ions (Cu2+) from aqueous solution. The effects of contact time, solution pH, temperature and initial Cu2+ concentration on the adsorption of Cu2+ onto the as-prepared samples were investigated. The chitosan modified CNTs composites showed high affinity and fast kinetics for the adsorption of Cu2+ ions, and adsorption capacity of the composites was found to be 2 times that of pristine CNTs. Adsorption kinetics and thermodynamic indicated a spontaneous and endothermic nature of the adsorption of Cu2+ on the surface of chitosan-coated CNTs composites, kinetically obeyed the pseudo-second-order model. Equilibrium data could be best described by the Langmuir isotherm model, with a maximum monolayer adsorption capacity of 115.84 mg/g. In view of the extensive applicability of DA chemistry and MALI reaction, different carbon nanomaterials based composites with various functional groups could be fabricated and applicable to different fields such as environmental catalysis and biomedicine.