UO₂ ²⁺ Ion Capture Enhanced with SiO2-based Compound: Insights into Kinetic, Thermodynamics, and Transport Analysis

A new material of SiO₂-(1-(bis(2-aminoethyl)amino)-3-(silyl)propane-2-ol) (SiO₂- BAEASP) has been successfully synthesized as a promising SiO₂-based material for the filtration and capturing UO₂ ²⁺ ions. In this study, the chemical structure and possible uses of SiO₂-BAEASP in environmental remediation are explored. Moreover, the methodologies and procedures for synthesizing and characterizing SiO₂-BAEASP are also described. In addition, the experimental methodologies regarding the capturing capacity, pH, initial concentrations, and temperature dependence are determined. The FT-IR spectra of SiO₂-BAEASP materials show distinct functional groups, including the disappearance of ν_Si–O–H stretching vibrations and the appearance of sharp ν_Si–O–Si vibrations. However, detection of the primary and secondary amine stretching frequencies at 3251 cm-1 becomes difficult when it is chelated with UO₂²⁺ ions due to its weak density and interference with the –OH stretching frequency. Thermogravimetric analysis (TGA) and weight loss patterns for SiO₂-BAEASP before and after capturing UO₂²⁺ ions suggest the formation of coordination complexes between UO₂²⁺ ions and organic functional groups, impacting the thermal properties of the material. Furthermore, the Powder X-ray Diffraction (PXRD) spectrum indicates that the atomic arrangement within the crystals of the material remains largely unchanged before or after adsorption, suggesting that the adsorption of uranyl ions is likely to occur predominantly on the material's surface, with limited impact on the bulk structure. The SEM shows an increase in surface roughness or the formation of layers of nano-spherical particles on the surface, forming clusters or agglomerations. The maximal capturing capability of UO₂²⁺ ions into SiO₂-BAEASP is 99% under the experimental circumstances of pH = 5 - 7, C_i = 50 mg L^-1, T = 55°C, dosage = 2 g L^-1, and 80 rpm. The capturing of uranyl ions follows the Langmuir isotherm model (R² ≈ 1) as a favorable process (<i>R_l</i> < 0.02). The capturing process has &#916;G = − 8.2083 to -16.0568 kJ mol^-1, &#916;H (+69.7927 kJ mol−1), and &#916;S (+2.616166 kJ mol^-1 K^-1), which indicates that the adsorption is energy-efficient and spontaneous. The pseudo-secondorder and Weber-Morris intraparticle diffusion models (ca. <i>R²</i> = 1.0) suggest that the capturing mechanism follows chemisorption through three distinct stages of sorption, indicating that intraparticle diffusion primarily governs the transport of UO₂²⁺ ions into the SiO₂-BAEASP. The main findings confirm the ability of SiO₂-BAEASP to trap UO₂²⁺ ions in contaminated fluids efficiently and its importance in environmental remediation and resource recovery.