Adsorption of Gd3+ in water by N, S Co-doped La-based metal organic frameworks: Experimental and theoretical calculation

Abstract

There is a growing need for ultra-pure gadolinium, making it ever more important to control pollution from industrial use. For this reason, it is extremely significant to successfully recover Gd3+ from real wastewater. In this work, La-based metal organic framework material (LaBDC) was synthesized by solvothermal method, and 4,6-Diamino-2-mercaptopyrimidine (DMP) was loaded on LaBDC by impregnation method, thus a new and environmentally friendly composite material LaBDC@xDMP was prepared. X-ray diffraction(XRD), thermogravimetric analysis(TGA), X-ray photoelectron spectroscopy(XPS), and a scanning electron microscope(SEM) were all used to learn more about the adsorbent. A combination of batch experiments and density functional theory (DFT) simulations were used to deduce LaBDC@DMP's adsorption performance and mechanism for Gd3+. The adsorption capacity of LaBDC and LaBDC@60%DMP for Gd3+ was consistent with the pseudo-second-order kinetic model and the Langmuir isotherm model, and it was found to be maximized at a DMP load of 60%. However, the removal of Gd3+ by LaBDC@60%DMP is more stable, and its removal capacity (241.4 ​mg/g) is much higher than LaBDC(35.6 ​mg/g). Importantly, LaBDC@60%DMP showed excellent selectivity in the presence of Na+, NH4+, Ca2+, Mg2+, and Al3+. In the end, the potential mechanisms of LaBDC@60%DMP are concluded by characterization analysis and DFT calculation, such as surface complexation, electrostatic attraction, hydrogen bonding, and ion exchange.