Sorption and removal of iodate from aqueous solution using dried duckweed (Landoltia punctata) powder

Proficiency of some synthetic alginate derivatives for sequestration of Iodine-131 from radioactive liquid waste

The current effort in environmental remediation is aimed at removing iodine-131 radionuclide from radioactive liquid waste produced by an Egyptian nuclear power plant using some synthesised alginate derivatives. Two different copolymers, namely sodium alginate poly (acrylic acid) (P1) and sodium alginate poly (acrylic acid-methacrylic acid) (P2), are prepared using gamma radiation. The ability of these polymers to remove 131I radionuclide as sorbents has been investigated. The synthesised polymers exhibit excellent adsorption performance for 131I ions, and the adsorption equilibrium requires only 30 min, which reveals that the sorption process is kinetically faster than most of the other materials reported previously. The removal percents for 131I radionuclide at a pH of 3.0 at room temperature on P1 and P2 are 77.7% and 84.2%, respectively. The sorption capacities of the two polymers demonstrate that P2 > P1, with capacities of 67.9 and 58.5 mg/g, respectively. Four linear kinetic models are investigated: pseudo-first order, pseudo-second order, Elovich, and Weber-Morris models. Regarding their calculated parameters, these models indicate that the adsorption process of I-ions on both P1 and P2 is controlled by chemisorption. Four equilibrium isotherm models (Redlich-Peterson, Langmuir, Freundlich, and Harkin-Jura) are investigated, revealing that the adsorption process is a monolayer and multilayer process on a heterogeneous surface.

Unraveling the mechanism of iodate adsorption by anthocyanin-rich fruit waste as green adsorbents for Applications of radioactive iodine remediation in water environment

In aquatic settings, radioactive iodine from nuclear waste can exist as iodate (IO3-). This study explored the efficiency and mechanism of IO3- adsorption by minimally modified anthocyanin-based adsorbents. Pomegranate peels and mangosteen pericarps were selected from an initial screening test and could remove over 70% of 10 mg/L IO3-. The adsorbents yielded adsorption capacity (q) of 9.59 mg/g and 2.31 mg/g, respectively, at room temperature. At 5 °C, q values increased to 14.5 and 5.13 mg/g, respectively. Pomegranate peels showed superior performance, with approximately 4 times the anthocyanin content of mangosteen pericarps. Both adsorbents took 120 min to reach adsorption equilibrium, and no desorption was observed after 8 days (I-131 half-time). Confirmation of physisorption was indicated by the fit of the pseudo-first-order reaction model, negative entropy (exothermic), and negative activation energy (Arrhenius equation). IO3- inclusion was confirmed through adsorbent surface modifications in scanning electron microscope images, the increased iodine content post-adsorption in energy-dispersive X-ray spectroscopy analysis, and alterations in peaks corresponding to anthocyanin-related functional groups in Fourier transform infrared spectroscopy analysis. X-ray absorption near-edge spectroscopy at 4564.54 eV showed that iodine was retained in the form of IO3-. Through the computational analysis, electrostatic forces, hydrogen bonds, and π-halogen interactions were deduced as mechanisms of IO3- adsorption by anthocyanin-based adsorbents. Anthocyanin-rich fruit wastes emerged as sustainable materials for eliminating IO3- from water.

Development of bismuth-functionalized graphene oxide to remove radioactive iodine

Bismuth-functionalized graphene oxide shows high performance in the removal of radioactive iodine.