The sequestration of Sr(II) and Cs(I) from aqueous solutions by magnetic graphene oxides

The adsorption of Sr(II) and Cs(I) on magnetic graphene oxides was investigated by batch techniques. The adsorption kinetics indicated that adsorption of Sr(II) and Cs(l) on magnetic graphene oxides can be satisfactorily fitted by pseudo-second-order kinetic model. The adsorption of Sr(II) and Cs(I) on magnetic graphene oxides increased with increasing pH from 2.0 to 6.0, then high level adsorption of Sr(II) and Cs(I) was observed at pH > 6.0. The maximum adsorption capacity of magnetic graphene oxides calculated from Langmuir model at pH 4.0 and 293 K was 14.706 and 9259 mg/g for Sr(II) and Cs(I), respectively. The thermodynamic parameters showed that the adsorption of Sr(II) and Cs(I) on magnetic graphene oxides was an exothermic and spontaneous process. According to surface complexation modeling, the adsorption mechanism of Sr(II) and Cs( I) on magnetic graphene oxides was cation exchange, whereas the inner-sphere surface complexation dominated the sorption mechanism of Sr(II) and Cs(I) on magnetic graphene oxides. The finding suggested that magnetic graphene oxides can be one of the promising adsorbents for the immobilization and preconcentration of radionuclides from aqueous solutions in environmental cleanup. (C) 2015 Elsevier B.V. All rights reserved.