Quasi-complete separation Re(VII) from Mo(VI) onto magnetic modified cross-linked chitosan crab shells gel by using kinetics methods

Abstract

In this work, a novel di-2-ethylhexylamine modified magnetic chitosan (FCS-DIOA) was successfully synthesized and used to recovery Re(VII) in Mo-Re binary mixtures. The percentage content and the chemical structure of adsorbent were characterized by elemental analysis, gas sorption, magnetic properties, X-ray diffraction analysis, infrared spectroscopy, and Boehm titration, respectively. We discussed the effects of steric hindrance and basic strength of the secondary, the tertiary ammonium, or the quaternary ammonium gel on rhenium adsorption selectivity and capacity. More important, Re-Mo binary component separations on the FCS-DIOA gel consistently showed that the kinetic separation method exhibited a greater sorption capacity and selectivity (SelRe/Mo = 1.70-4.40). It was found that rhenium(VII) was adsorbed on the FCS-DIOA via charge-interactions and complexation by an infrared spectroscopy and X-ray photoelectron spectroscopy analysis. Relationships between adsorption mechanism and pH, adsorption isotherms, adsorption kinetics, adsorption thermodynamics, desorption, and regeneration were also discussed.