Efficient Uranium Removal from Aqueous Solutions Using Silica-Based Adsorbents Functionalized with Various Polyamines

With the rapid development of nuclear energy, the contamination of environmental water systems by uranium has become a significant threat to human health. To efficiently remove uranium from these systems, three types of silica-based polyamine resins-SiPMA-DETA (SiPMA: silica/poly methyl acrylate; DETA: diethylenetriamine), SiPMA-TETA (TETA: triethylenetetramine), and SiPMA-TEPA (TEPA: tetraethylenepentamine)-were successfully prepared, characterized, and evaluated in batch experiments. Characterization results showed that the silica-based polyamine resins were successfully prepared, and they exhibited a uniform shape and high specific surface area. SiPMA-DETA, SiPMA-TETA, and SiPMA-TEPA had nitrogen contents of 4.08%, 3.72%, and 4.26%, respectively. Batch experiments indicated that these adsorbents could efficiently remove uranium from aqueous solutions with a pH of 5-9. The adsorption kinetics of U(VI) were consistent with the pseudo-second-order model, indicating that the adsorption process was chemisorption and that adsorption equilibrium was achieved within 10 min. SiPMA-TEPA, with the longest polyamine chain, exhibited the highest adsorption capacity (>198.95 mg/g), while SiPMA-DETA, with the shortest polyamine chain, demonstrated the highest U(VI) adsorption efficiency (83%) with 100 mM Na₂SO₄. SiPMA-TEPA still removed over 90% of U(VI) from river water and tap water. The spectral analysis revealed that the N-containing functional groups on the ligand were bound to anionic uranium-carbonate species and possibly contributed to the adsorption efficiency. In general, this work presents three effective adsorbents for removing uranium from environmental water systems and thus significantly contributes to the field of environmental protection.