Silica-Based 1,3-Diphenyl-1,3-Propanedione Composites: Efficient Uranium Capture for Environmental Remediation

Introduction: This study synthesizes and characterizes a novel hybrid composite, SGdpm, to capture UO2²⁺ ions from water. The composite has successfully formed by hosting covalently diphenylmethane-1,3-dione (dpm) within an inorganic silica gel matrix, showing promising potential for environmental remediation and nuclear waste management. Methods: The preparation involved the reaction of tetraethylorthosilicate (TEOS) with diphenylmethane- 1,3-dione (dpm) under acidic conditions, resulting in white solids. The doped composite was characterized by Fourier Transform Infrared Spectroscopy (FTIR), revealing the presence of siloxane and Si-O-C bonds. The application of SG-dpm for capturing UO2²⁺ ions from water was investigated, showing a shift in FTIR peaks and confirming the formation of SG-dpm-UO2²⁺ as inner-sphere complexes. Scanning Electron Microscopy (SEM) revealed a non-uniform distribution of particles, essential for consistent behavior in applications such as adsorption. Results and Discussion: Batch sorption experiments demonstrated temperature-dependent sorption behavior with increased efficiency at higher temperatures (T = 55°C). The study also explored the influence of pH and initial concentration on UO2²⁺ sorption, revealing optimal conditions at pH 5 and lower initial concentrations (1.0 mg L^-1). Kinetic studies using pseudo-second-order models indicated a high efficiency of UO2²⁺ ion removal (99%) as a chemisorption process. Intraparticle diffusion models highlighted three distinct sorption stages. Sorption isotherm studies favored the Langmuir model, emphasizing monolayer adsorption. The thermodynamic analysis suggested an endothermic (ΔH = + 16.120 kJ mol^-1) and spontaneous (ΔG = −25.113 to − 29.2449 kJ mol^-1) sorption process. Selectivity studies demonstrated high efficiency in capturing Cu²⁺, Co²⁺, and Cr³⁺ ions, high degree selectivity of UO2²⁺ ions (74%), moderate efficiency for Fe³⁺ and Zn²⁺, and lower efficiency for Pb²⁺, Ni²⁺, and Cd²⁺, and poor efficiency for Mn²⁺ ions. Conclusion: SG-dpm exhibits promising potential for selective UO2²⁺ ion removal, demonstrating favorable characteristics for various applications, including environmental remediation and nuclear waste management.