High Removal Efficiencyof Radioactive Iodine withIn Situ-Synthesized Ag₂O–Mg(OH)₂ PlateComposites

To promote the capacity of adsorbing radioactive iodine (I^–) in acid and alkaline situations, a high-removal-efficiency adsorbent based on silver oxide (Ag₂O) and magnesium hydroxide (Mg(OH)₂) was synthesized by the in situ method. To determine the mechanism of this novel absorbent, batch experiments related to the temperature, pH, competitive ion (Cl^–), and kinetic analysis were carried out. The results showed that the Ag₂O–Mg(OH)₂ plate composites had high adsorption capacity and efficiency for I^– (409 mg/g, 25 °C) with a wide range of pH values (3–9). In addition, the adsorption time from the initial concentration to I^– removal (97.36%) was only 20 min. Competitive ion experiments depicted that Cl^– influenced the capacity of adsorbing I^–. The <i>k</i> value of the pseudo-second-order model and regression factor <i>R</i>² were 7.86 × 10^–3g mg^–1 min^–1 and 0.999 at 25 °C, respectively. The kinetics and XPS results proved that the mechanism of adsorption was chemical adsorption. Compared with other commercial adsorbents, the Ag₂O–Mg(OH)₂ plate composites had potential for application in nuclear wastewater treatment with low cost and high efficiency.