Preparation of a novel silica-based N-donor ligand functional adsorbent for efficient separation of palladium from high level liquid waste

Abstract

In this work, a novel silica-based N-donor ligand functional adsorbent (SiVpC) is prepared by in situ polymerization for the efficient separation of palladium from high level liquid waste (HLLW). The as-prepared SiVpC adsorbent is characterized by SEM-EDS, TGA, and BET. The effects of nitric acidity, SiVpC adsorbent dosage, time, temperature, and palladium ion concentration on the adsorption are investigated. Among the 12 typical fission product metal ions (Ru, Rh, La, Y, Pr, Ce, Sm, Nd, Gd, Eu, Zr, Mo) existing in HLLW, SiVpC adsorbent can selectively adsorb palladium (SFPd/other metals = 137.6) in 0.5 M HNO3 solution. The adsorptio kinetics of Pd(II) are consistent with the pseudo-second-order model, reaching equilibrium within 120 min. The maximum adsorption capacity is 38.4 mg/g in 0.5 M HNO3, and the adsorption process is consistent with the Langmuir model. The adsorbed palladium can be completely desorbed with 0.5 M HNO3-0.5 M Thiourea. Furthermore, SiVpC adsorbent remains good performance after five adsorption–desorption cycles, which indicates good reusability. The adsorption mechanism of SiVpC adsorbent on palladium is analyzed by FT-IR and XPS that N-containing functional groups on the ligand are coordinated with palladium, which is also further verified by DFT calculations. In addition, through the column chromatography separation system, SiVpC adsorbent can efficiently adsorb palladium from HLLW and the adsorbed palladium can be desorbed with 0.5 M HNO3-0.5 M thiourea solution, which has great application potential.