Bio-inspired quercetin-silica-alginate hybrid beads for sustainable uranium removal from aqueous solution

Uranium contamination in industrial effluents remains a critical global challenge, requiring sustainable and high-efficiency adsorbents for large-scale treatment. However, many existing biopolymer-based materials suffer from limited stability, limited active-sites and weak metal-binding performance. In this study, a novel bio-inspired quercetin-silica-alginate hybrid beads were engineered to create multiscale active sites combining carboxyl, silanol, and polyphenolic coordination domains. The hybrid beads were characterized utilizing Fourier transform infrared spectroscopy (ATR-FTIR) to elucidate surface chemistry, Electron microscopy in scanning mode (SEM) to clarify morphological characteristics, and Zeta potential analysis to reveal the surface charge characteristics and dispersion stability. A series of examinations was carried out at pH values (2–8), hybrid beads dose (0.025–0.4 g), uranium concentrations (25–250 mg/L), varying durations (10–150 min), variable temperatures (25–55°C), solution volume of 10 ml, and at 150 rpm, to optimize uranium adsorption process. The hybrid beads exhibited a significantly enhanced affinity toward U(VI), achieving a maximum adsorption capacity of 58.4 mg/g at pH 4.0, a biomass dosage of 0.3 g, a contact duration of 60 min, and U(VI) concentration of 250 mg/L at ambient temperature. Kinetic and isotherm analyses revealed a dominant Freundlich model and pseudo-second-order with strong chemisorption contributions and multilayer biosorbent surface. Thermodynamic results revealed endothermic, spontaneous, and less ordered adsorption system. 0.5 M HCl showed high efficiency (95%) in uranium removal from quercetin-silica-alginate hybrid beads assisting in multiple recycling and frequent uses in uranium bioremediation.