Clay-polymer composite adsorbents for in situ uranium remediation in groundwater: Adsorption mechanism, reusability, and field-scale performance estimation

This study presents the development and evaluation of a montmorillonite–polysulfone sorbent (MPS) designed for the remediation of uranium-contaminated groundwater. The composite was synthesized by embedding montmorillonite (MMT) into a polysulfone (PSF) matrix to combine the high adsorption capacity of layered silicates with the mechanical stability of synthetic polymers. Batch experiments were conducted to investigate the effects of MMT content, pH, contact time, and uranium (U) concentration on adsorption behavior. Optimal performance was achieved with 4 wt% MMT, showing >99 % adsorption efficiency at pH 7.0. Kinetic data were best described by the pseudo-first-order model ( R 2 = 0.969), while the Elovich model captured late-stage adsorption behavior, suggesting a two-phase mechanism involving rapid physisorption followed by slower chemisorption. Isotherm analysis indicated that both Langmuir and Freundlich models fitted the data well, with a maximum adsorption capacity of 453.7 μg/g. SEM-EDS characterization confirmed U penetration into both surface and internal pore structures of MPS. Reusability tests demonstrated sustained adsorption (≥95 %) and desorption (≥93 %) efficiencies over ten cycles using 0.1 M HNO₃. In continuous-flow permeable reactive barrier (PRB) system, MPS maintained U removal efficiencies >95 % over 34 pore volumes, with minimal breakthrough. Field-scale modeling suggests that an MPS-based PRB can treat 3.27 × 10 4 m 3 of groundwater over 7 yr with ten regeneration cycles. These findings highlight the structural robustness and practical applicability of MPS for in situ U remediation under realistic hydrogeological conditions. • A montmorillonite–polysulfone sorbents (MPS) was developed as a novel U adsorbent. • MPS showed >99 % efficiency and 453.7 μg/g adsorption capacity at optimal conditions. • Adsorption kinetics followed rapid physisorption and slow chemisorption. • Reusability by HNO₃ was over 93 %, ensuring long-term sustainability. • PRB simulation showed long-term use, treating 3.27 × 10 4 m 3 U-contaminated water.