Adsorption of neodymium,terbium and dysprosium using a synthetic polymer-based magnetic adsorbent

In this study,a polyamide with methine-thiophene and pyrimidine linkages(poly(pyrimidine-thiophene-amide)(PPTA))was synthesized.Then,magnetic PPTA(M-PPTA)was synthesized using the hydrothermal technique.The products were analyzed by Fourier-transform infrared spectroscopy(FTIR),nuclear magnetic resonance(NMR),X-ray diffraction(XRD),thermogravimetric analysis(TGA),field-emission scanning electron microscopy(FE-SEM),and a vibrating-sample magnetometer(VSM).The nanocomposite exhibits a saturation magnetization of 50.44 emu/g recorded by VSM analysis.The ability of M-PPTA to bind dysprosium(Dy^(3+)),terbium(Tb^(3+)),and neodymium(Nd^(3+))was investigated.Using 0.15 g of M-PPTA to test the adsorption of the rare earth elements(50 mg/L)at pH=5.5,the percentage of adsorption for Dy^(3+),Tb^(3+),and Nd^(3+)is 98.41%,97.48%and 95.67%,respectively.Pseudo-second-order(PSO)significantly fits the adsorption kinetic data.Freundlich equation was used to describe the adsorption equilibrium data of Dy^(3+)and Tb^(3+),while Langmuir model was used to simulate Nd^(3+)adsorption data.Increasing the temperature leads to an increase in the performance of M-PPTA,and an endothermic adsorption process was confirmed by the positive values ofΔH.After four adsorption-desorption cycles,the efficiency of adsorption of Dy^(3+),Tb^(3+),and Nd^(3+)by M-PPTA is88.75%,86.37%,and 84.64%,respectively.An antagonism effect is observed for the adsorption of the individual ions in a ternary solution.