Efficient and Selective Removal of Palladium from Simulated High-Level Liquid Waste Using a Silica-Based Adsorbent NTAamide(C8)/SiO-P.

In order to realize the effective separation of palladium from high-level liquid waste (HLLW), a ligand-supported adsorbent (NTAamide(C8)/SiO-P) was prepared by the impregnation method in a vacuum. The SiO-P carrier was synthesized by in situ polymerization of divinylbenzene and styrene monomers on a macroporous silica skeleton. The NTAamide(C8)/SiO-P adsorbent was fabricated by impregnating an NTAamide(C8) ligand into the pore of a SiO-P carrier under a vacuum condition. The adsorption performance of NTAamide(C8)/SiO-P in nitric acid medium has been systematically studied. In a solution of 0.2 M HNO, the distribution coefficient of Pd on NTAamide(C8)/SiO-P was 1848 mL/g with an adsorption percentage of 90.24%. With the concentration of nitric acid increasing, the adsorption capacity of NTAamide(C8)/SiO-P decreases. Compared to the other 10 potential interfering ions in fission products, NTAamide(C8)/SiO-P exhibited excellent adsorption selectivity for Pd(II). The separation factor (SF > 77.8) is significantly higher than that of similar materials. The interference of NaNO had a negligible effect on the adsorption performance of NTAamide(C8)/SiO-P, which maintained above 90%. The adsorption kinetics of Pd(II) adsorption on NTAamide(C8)/SiO-P fits well with the pseudo-second order model. The Sips model is more suitable than the Langmuir and Freundlich model for describing the adsorption behavior. Thermodynamic analysis showed that the adsorption of Pd(II) on NTAamide(C8)/SiO-P was a spontaneous, endothermic, and rapid process. NTAamide(C8)/SiO-P also demonstrated good reusability and economic feasibility.