Sorption and Possible Preconcentration of Europium and Gadolinium Ions from Aqueous Solutions by Mn3O4 Nanoparticles

Mn3O4 nanoparticles were prepared by co-precipitation method. The prepared samples had been characterized to find the compositional, structural, and functional properties, by means of EDX, XRD, and FTIR, respectively. The prepared manganese oxide nanoparticles (Mn3O4 NPs) have average crystallite size of 30–35 nm. The effect of different parameters on the uptake of Eu(III) and Gd(III) by Mn3O4 nanoparticles such as pH, initial metal concentration, shaking time, and temperature was examined. The shaking time for both adsorption and desorption was found to be 5 h. The sorption capacities at equilibrium with regards to Eu(III) and Gd(III) were 26.8 and 12.6 mg/g, respectively. Kinetically, the sorption of both elements fitted well to pseudo-second-order model. Sorption equilibrium isotherm obeys more favorably the Langmuir isotherm model. Desorption process of Eu(III) and Gd(III) from Mn3O4 NPs was highly managed using 2.0 M HNO3. A preconcentration factor of 70 and 20 was obtained for Gd and Eu, respectively, using 0.1 g of the Mn3O4 nanoparticles.