水系からのウラン(VI)除去のための多孔質アルミノケイ酸吸着剤としての熱活性化リサイクル陶器廃棄物

The sustainable management of radioactive wastewater requires low-cost and eco-friendly materials capable of efficiently removing U(VI) from aqueous systems. In this work, recycled pottery waste, a ubiquitous aluminosilicate by-product, was thermally activated at 550, 650, and 750 °C to produce novel sorbents (RP1-RP3) for U(VI) adsorption. The materials were comprehensively characterized by XRD, SEM-EDS, BET, DLS, zeta potential, and FTIR to elucidate structural and surface modifications induced by calcination. The results revealed a progressive improvement in crystallinity, porosity, and surface charge with temperature, culminating in RP3 (750 °C) exhibiting the highest surface area (34.35 m² g^-1) and most negative zeta potential (-38.46 mV). Batch adsorption studies demonstrated that U(VI) removal strongly depended on pH, sorbent dose, and contact time, with optimal uptake achieved at pH ≈ 4. The adsorption followed pseudo-second-order kinetics and was best fitted by the Langmuir and Sips isotherm models, confirming monolayer chemisorption on homogeneous active sites. The maximum adsorption capacities reached 49.5 mg g^-1 for RP3, while thermodynamic parameters indicated a spontaneous, endothermic, and entropy-driven process. Mechanistic interpretation supported a multi-step pathway involving electrostatic attraction, surface complexation, and intraparticle diffusion. RP3 exhibited excellent reusability, maintaining >87% adsorption efficiency after five cycles using H₂SO₄ as an effective desorbing agent. When tested with real radioactive wastewater, RP3 achieved a 74.2% U(VI) removal efficiency despite competing ions, confirming its high selectivity and structural stability. This study establishes thermally activated recycled pottery as a cost-effective, reusable, and environmentally sustainable sorbent for uranium (VI) remediation, integrating waste valorization with Radioprotection.