Novel environment-friendly magnetic bentonite nanomaterials functionalized by carboxymethyl chitosan and 1-(2-pyridinylazo)-2-naphthaleno for adsorption of Sc(III)

Abstract

Abstract For effective adsorption and separation of precious rare metal scandium (Sc) from waste water, a new bifunctional magnetic bentonite material was prepared, named bentonite/CoFe2O4@SiO2-CMC/PAN to enhance the selective extraction of scandium. Magnetic bentonite was functionalized with carboxymethyl chitosan (CMC) and 1-(2-pyridinylazo)-2-naphthaleno (PAN). The adsorbent was characterized by BET, XRD, EDS, SEM, TEM and FTIR. Factors such as pH, initial concentration, reaction time, adsorbent dosage, selectivity, and reusability were systematically investigated. The results showed that the adsorption isotherm and kinetic data were accurately described by Langmuir model and pseudo second order model, indicating that the adsorption conformed to the monolayer chemical adsorption, and the adsorption rate was controlled by multiple steps. The adsorption rate was 98%, and the maximum adsorption capacity was up to 49.05\xa0mg·g−1. The bentonite/CoFe2O4@SiO2-CMC/PAN showed high selectivity. Additionally, the adsorbent could be magnetically separated quickly. XPS analysis results showed that scandium ion (Sc(III)) could not only carry out electrostatic and complexation with carboxyl groups and hydroxyl, but also chelate with amino, azo and pyridine groups. In general, bentonite/CoFe2O4@SiO2-CMC/PAN showed a hopeful way for the recovery and utilization of Sc.