Synergistic adsorption behaviors of a silica-based (TEHTDGA + TAMIA-EH)/SiO2–P composite toward palladium and other metals in simulated high-level liquid waste

In this work, a silica-based adsorbent incorporating two types of extractants was synthesized through vacuum-assisted impregnation. The synergistic adsorption behaviors of the prepared (TEHTDGA + TAMIA-EH)/SiO 2 –P composite toward 14 types of representative metal ions in simulated high-level liquid waste were systematically investigated under different contact durations, nitric acid concentrations, and solution temperatures, revealing the strong affinity of the (TEHTDGA + TAMIA-EH)/SiO 2 –P composite toward Pd(II), Ru(III), Re(VII), Mo(VI), and Zr(IV). Particularly, Pd(II) rapidly adsorbed on the composite, reaching equilibrium within 2h, with a removal efficiency exceeding 95%. Notably, the adsorption performance of the (TEHTDGA + TAMIA-EH)/SiO 2 –P composite toward Pd(II) remained stable across broad ranges of nitric acid concentration (0.1–5M) and temperature (288–323K), indicating its strong acid tolerance and thermal stability. Furthermore, the adsorbed Pd(II) was effectively eluted using 0.01M thiourea ([HNO 3 ] = 1M) in chromatographic experiments.