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

Abstract

A fabricated silica gel, SiO2-(1-(bis(2-aminoethyl)amino)-3-(silyl)propane-2-ol), SiO2-BAEASP, has successfully enhanced the capture of UO22+ ions from water in an unprecedented study. The reported studies examine the removal of uranyl ions, specifically focusing on the efficiency, selectivity, and cost-effectiveness of traditional removal methods including various adsorbents, nanomaterials, and functionalized surfaces. The primary objective of this study is to investigate the capturing capabilities of SiO2-BAEASP for aqueous uranium (VI) ions through batch sorption techniques. Several key parameters affecting sorption, including pH, initial concentration, temperature, and dosage, were meticulously controlled to gain insights into the capturing process's thermodynamic and kinetic aspects and determine the mechanisms involved. The equilibrium of the capturing process was observed to occur within just 5 to 10 minutes under a variety of conditions. The maximum capturing capacity of uranium (VI) ions into SiO2-BAEASP is found to be ca. 99% under the experimental conditions of pH = 5 - 7, Ci = 50 mg L-1, T = 55 °C, dosage = 2 g L-1, and 80 rpm. The sorption behavior of U(VI) ions on SiO2-BAEASP followed the Langmuir isotherm model (R2 ≈ 1), indicating favorable (Rl < 0.02) and spontaneous sorption of ΔG =  39.874 to 49.079 kJ mol-1. The motivation for the sorption process was attributed to the chemisorption of U(IV) ions via amino active sites, forming an inner complex sphere of the general form SiO2-BAEASP-U(VI). This finding was supported by the pseudo-second-order kinetic model (R2 ≈ 1), which provided insights into the rate constant and sorption capacities. The obtained information could potentially be utilized to develop a technology utilizing new materials of SiO2-BAEASP for catching uranium ions from water or for peaceful reuse applications. Overall, this study adds to the existing body of knowledge on water treatment, filling a notable gap in the literature and paving the way for further research and development of innovative materials for the removal of uranyl ions and other heavy metal contaminants from water sources.