Enhanced adsorption-oxidation of Sb(III) over chitosan bimetallic beads: In-situ generated O2•– and autocatalytic effect of Sb(III)

Abstract

Recently, the oxidation-coupled adsorption technologies for Sb(III) detoxification as well as adsorption are of great concern. To develop a kind of material for not only improving the Sb(III) adsorption efficiency but also enabling the oxidation of the adsorbed Sb(III) with low reagent or energy consumption, we prepared a magnetite-cuprite@chitosan bead adsorbent (nMC@CS) using a one-step method. Batch experiments and characterization of the beads demonstrated that Sb(III) adsorption was highly dependent on the Fe3O4 nanoparticles in the beads, and the adsorbed Sb(III) was oxidized by the reactive oxygen species (ROS) generated in-situ upon activation of the dissolved oxygen by Cu(I). Importantly, the Sb(III) adsorbed onto the surface of the beads could effectively catalyze the redox cycles of Fe(III)/Fe(II) and Cu(II)/Cu(I) in the system through the generation of O2•– while being oxidized to Sb(V), forming a closed-loop circulation of electrons. This cyclic electron transfer facilitated the adsorption-oxidation process of Sb and further improved their synergistic efficiency. Under the optimal adsorption conditions, 97.4% of the Sb(III) in solution was adsorbed onto the nMC@CS, 84.3% of which was oxidized to Sb(V), providing a simple and promising strategy for efficient Sb(III) adsorption and simultaneous detoxification.