Radiation Resistance and Adsorption Behavior of Aluminum Hexacyanoferrate for Pd

Irradiation resistance is important for adsorbents used in radioactive environments such as high-level liquid waste. In this work, a silica-based composite adsorbent (KAlFe(CN)(6)/SiO(2)) was synthesized and γ-irradiated from 10 to 1000 kGy. The angles of the main X-ray diffraction peaks slightly decreased with the increase in irradiation dose, and a minor decomposition of CN(−) occurred after irradiation to 1000 kGy, indicating that the KAlFe(CN)(6)/SiO(2) adsorbent could preserve structural integrity with a dose below 100 kGy. In 1 to 7 M HNO(3), the adsorption ability of the irradiated KAlFe(CN)(6)/SiO(2) remained performant, with a higher K(d) than 1625 cm(3) g(−1). The adsorption equilibrium of Pd(II) in 3 M HNO(3) was attained within 45 min before and after irradiation. The maximal adsorption capacity Q(e) of the irradiated KAlFe(CN)(6)/SiO(2) on Pd(II) ranged from 45.1 to 48.1 mg g(−1). A 1.2% relative drop in Q(e) was observed after 100 kGy irradiation, showing that γ-irradiation lower than 100 kGy insignificantly affected the adsorption capacity of KAlFe(CN)(6)/SiO(2). Calculating and comparing the structures and free energies of different adsorption products via the density functional theory (DFT) method showed that KAlFe(CN)(6)/SiO(2) was more inclined to completely adsorb Pd(II) and spontaneously generate Pd[AlFe(CN)(6)](2).