Recyclable UiO-66-NH2@Chitosan/Loofah fiber composite for efficient strontium capture

The treatment of radioactive wastewater containing 90 Sr required advanced adsorbents to address the limitations of the recyclable usage. In this study, a UiO-66-NH 2 @Chitosan/Loofah Fiber Composite (UNCL) was synthesized using an impregnation strategy, enabling easy separation from the solution and efficient Sr 2+ removal. By integrating the good adsorption activity of UiO-66-NH 2 , interfacial modification capability of chitosan, and macrostructural advantages of loofah fiber, the composite achieved enhanced mass transfer efficiency and structural stability. UNCL achieved adsorption equilibrium within 120 min, demonstrating rapid and efficient strontium capture capability. The material demonstrated robust performance under alkaline conditions, and retained high efficacy in real river water and seawater environments. Adsorption behavior aligned with the Sips isotherm model (R 2  = 0.999) and pseudo-second-order kinetics (R 2  = 0.995) with maximum adsorption capacity of 7.64 mg/g, confirming monolayer chemisorption. Mechanistic investigations, supported by FT-IR and XPS analyses, revealed a synergistic mechanism involving ion exchange, surface complexation and electrostatic interactions at multiple active sites. UNCL maintained approximately 90 % removal efficiency after five adsorption–desorption cycles and enabled facile separation from aqueous solutions through simple mechanical retrieval. These results demonstrated that UNCL combined adsorption ability, reusability, and environmental adaptability, positioning it as a promising and practical solution for Sr 2+ remediation.