Efficient capture of ReO4− on magnetic amine-functionalized MIL-101(Cr): Revealing from selectivity to mechanism

The efficient decontamination of pertechnetate (99TcO4−) is an essential task for managing radioactive 99Tc in nuclear wastes. Perrhenate, (ReO4−), as a nonradioactive analog, exhibits almost identical physicochemical properties as 99TcO4−. Herein, a novel magnetic amine-functionalized MIL-101(Cr) (NH2-MIL-101(Cr)@Fe3O4) was prepared and used to efficiently remove ReO4− from solution for the facile magnetic separation. A series of environmental parameters were considered to investigate the adsorption performance of NH2-MIL-101(Cr)@Fe3O4. Experimental results suggested that NH2-MIL-101(Cr)@Fe3O4 has reached a satisfied adsorption capacity (~401 mg/g) and a very fast adsorption kinetics at pH 7.0. The selectivity for ReO4− was maintained even in the presence of interfering anions with relatively high concentrations. ReO4− were mainly captured by N-donor sites of the surface-decorated amine via complexation and were trapped in the cavities of modified MIL-101(Cr). NH2-MIL-101(Cr)@Fe3O4 exhibits satisfactory adsorption performance for ReO4− and can be conveniently separated from wastewaters after adsorption.