Extraction of uranyl peroxo clusters from aqueous solution by mesoporous silica SBA-15

Soluble uranyl peroxo clusters in aqueous solution are potentially important for the transport and remediation of uranium. We studied extraction of one of such clusters, U60 [(Li_48+mK₁₂(OH)_m[UO₂(O₂)(OH)]₆₀(H₂O)_n, m ≈ 20, n ≈ 310 in the solid state], from aqueous solution using mesoporous silica SBA-15. A steady state was reached after 24 h with the extraction efficiency of 97.1 % and a distribution coefficient of 886.8 mL g⁻¹. Both pseudo-first-order and pseudo-second-order models describe the extraction kinetics, although the pseudo second-order model has a slightly higher correlation coefficient and a calculated extraction capacity at steady state (6.48 mg g⁻¹) closer to the experimental value (6.77 mg g⁻¹).