Development of phosphate-based porous organic polymers as multifunctional adsorbents for efficient removal of iodine in the vapor phase and uranium(VI) from contaminated groundwater

Abstract

With the rapid expansion of the nuclear energy sector, the release of radioactive contaminants such as iodine and uranium from nuclear waste presents significant risks to public health and the environment. The effective production, containment, and long-term management of radioactive waste remain critical operational challenges. Consequently, there is an increasing demand for the development of advanced adsorbents capable of efficiently removing these hazardous substances. In this study, we investigate three novel phosphate-based porous organic polymers (POPs), namely, SBF-POP , TPM-POP , and TPE-POP , as multifunctional platforms for the selective and efficient adsorption of uranium and iodine from contaminated systems. Iodine vapor adsorption experiments demonstrate that the three POPs exhibit high adsorption capacities of 2.30, 1.93, and 1.85 g.g −1 , respectively, at 75 °C under ambient pressure. The adsorbed iodine can be rapidly desorbed in methanol, while the POPs retain their high adsorption performance over multiple adsorption-desorption cycles. Furthermore, the phosphate-based polymer SBF-POP exhibits a high uranium adsorption capacity of up to 112.35 mg.g −1 at pH 7.0, significantly surpassing the performance of many previously reported adsorbents. The material achieves a uranium removal efficiency of 86 % within 30 min. Phosphate functional groups in SBF-POP are primarily responsible for uranium binding, acting as the main chelating sites. The adsorption process follows the Langmuir isotherm model and showed ultrafast kinetics, with a calculated kinetic constant value as high as 0.00426 g.mg −1 .min −1 . The adsorption mechanism has been elucidated using energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR), confirming that the interaction between phosphate groups and U(VI) ions is the primary mode of adsorption. Furthermore, SBF-POP demonstrates excellent reusability, maintaining over 80 % uranium removal efficiency after ten adsorption-desorption cycles. These findings suggest that phosphate-functionalized SBF-POP is a promising adsorbent for the efficient removal of uranium from contaminated groundwater, as well as radioactive iodine from the vapor phase.

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