Efficient Adsorptive Removal of Uranium (VI) from Aqueous Solutions Using Radiation-Grafted Phosphoryl-Functionalized Teflon Powder

In this study, a novel and reusable adsorbent effective over a wide pH range was developed through radiation-induced graft polymerization of glycidyl methacrylate (GMA) onto Teflon powder obtained from scrap Teflon, followed by postgrafting modification. Teflon powder, prepared by irradiating Teflon scraps, grinding, and sieving, served as the base material. GMA was grafted onto the Teflon powder by using Co-60 γ radiation. The epoxy groups in the grafted matrix were then converted to phosphoric acid groups by chemical modification with orthophosphoric acid at elevated temperatures, enabling strong binding with uranium ions. The functionalized adsorbent was evaluated for uranium (VI) uptake in aqueous solutions under batch and column conditions. At a neutral pH, the maximum sorption capacity for uranium was 72.4 mg/g. The effects of the contact time, initial uranium concentration, and pH on the sorption capacity were examined. The adsorption data followed the Langmuir isotherm model, with a separation factor (R L ) between 0 and 1, indicating favorable adsorption. Kinetic studies showed that the pseudo-second-order model best fit the experimental data, with a high coefficient of determination and strong agreement between experimental and calculated adsorption capacities. X-ray photoelectron spectroscopy (XPS) confirmed that uranium ions were adsorbed via surface complexation with the phosphate groups. The grafted adsorbent demonstrated excellent reusability, retaining nearly full adsorption capacity over six consecutive cycles. This study highlights the potential of radiation-engineered Teflon-based adsorbents for sustainable uranium removal, contributing to a circular economy and green chemistry principles.