Highly efficient capture of Eu(III), La(III), Nd(III), Th(IV) from aqueous solutions using g-C3N4 nanosheets

Graphitic-C3N4 (g-C3N4) nanosheets were prepared by a simple and environmentally friendly thermal oxidation etching method with ultrasonic. The crystal structure, surface functional groups, surface morphology of g-C3N4 and the adsorption of Eu(III), La(III), Nd(III) and Th(IV) on g-C3N4 were investigated. The maximum adsorption capacities of Eu(III), La(III), Nd(III) and Th(IV) on g-C3N4 were 155.0, 122.3, 132.5 and 185.6 mg/g at 333 K, which showed excellent adsorption capacity. The adsorption reached equilibriums within 7 h, and the adsorption kinetics of Eu(III), La(III), Nd(III) and Th(IV) followed the pseudo-second-order kinetic model well. The adsorption isotherms of La(III), Nd(III) fitted with Langmuir models but Eu(III), Th(IV) fitted with Freundlich models well, respectively. The calculation of thermodynamic data indicated the adsorption was a spontaneous and endothermic process. Experimental results of this work demonstrated that g-C3N4 nanosheets was a promising economical material for the removal of Eu(III), La(III), Nd(III) and Th(IV) from aqueous solutions.