Conversion of Waste-Derived Potato Starch into a β-CD Nanosponge Sorbent for Rare Earth Recovery from Mining Wastewater

), achieving maximum adsorption capacities of 147.79 mg/g and 151.21 mg/g, respectively, as described by the Langmuir isotherm model. Batch adsorption experiments revealed that the adsorption process followed pseudo-second-order kinetics, suggesting that chemisorption is the dominant mechanism. Characterization techniques, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA), together with density functional theory (DFT) calculations, indicated that the porous three-dimensional structure and the presence of abundant O-, N-, and P-containing functional groups facilitate adsorption through inner-sphere complexation. The adsorbent maintained over 71% removal efficiency after five adsorption-desorption cycles and exhibited strong selectivity in mining wastewater, achieving RE ion removal rates greater than 93% compared with less than 8% for competing ions. A cost evaluation revealed a low synthesis cost of $0.3471 per gram, suggesting good scalability. This paper presents a sustainable strategy for recovering RE ions and remediating wastewater, aligning with the principles of cleaner production and a circular economy.