nanomaterials Communication Removal of Radioactive Iodine Using Silver/Iron Oxide Composite Nanoadsorbents Mah Rukh Zia 1,† , Muhammad Asim Raza 2,3,† , Sang Hyun Park 2,3 , Naseem Irfan 1 , Rizwan Ahmed 1 , Jung Eun Park 4 , Jongho Jeon 4, * and Sajid Mushtaq 1,2,3, *   Citation: Zia, M.R.; Raza, M.A.; Park, S.H.; Irfan, N.; Ahmed, R.; Park, J.E.; Jeon, J.; Mushtaq, S. Removal of Radioactive Iodine Using Silver/Iron Oxide Composite Nanoadsorbents. Nanomaterials 2021, 11, 588. https:// doi.org/10.3390/nano11030588 Academic Editor: Christos A. Aggelopoulos Received: 8 February 2021 Accepted: 22 February 2021 Published: 26 February 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Department of Nuclear Engineering, Pakistan Institute of Engineering and Applied Sciences, P. O. Nilore, Islamabad 45650, Pakistan; Mahrukhzia14@gmail.com (M.R.Z.); naseem@pieas.edu.pk (N.I.); Rizwanahmed@pieas.edu.pk (R.A.) 2 Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 56212, Korea; masimraza@ust.ac.kr (M.A.R.); parksh@kaeri.re.kr (S.H.P.) 3 Radiation Science and Technology, University of Science and Technology, Daejeon 34113,Korea 4 Department of Applied Chemistry, College of Engineering, Kyungpook National University, Daegu 41566, Korea; pje1204@knu.ac.kr * Correspondence: jeonj@knu.ac.kr (J.J.); sajidmushtaq@pieas.edu.pk (S.M.); Tel.: +82-53-950-5584 (J.J.); +92-51-9248611-3716 (S.M.) † These Authors contributed equally to this study. Abstract: Efficient and cost-effective removal of radioactive iodine (radioiodine) from radioactive contaminated water has become a crucial task, following nuclear power plant disasters. Several materials for removing radioiodine have been reported in the literature. However, most of these materials exhibit some limitations, such as high production cost, slow adsorption kinetics, and poor adsorption capacity. Herein, we present silver/iron oxide nanocomposites (Ag/Fe 3 O 4 ) for the efficient and specific removal of iodine anions from contaminated water. The Ag/Fe 3 O 4 were synthesized using a modified method and characterized via scanning electron microscopy, transmis- sion electron microscopy, and X-ray diffraction analyses. This adsorbent showed a high adsorption capacity for iodine anions (847 mg/g of the adsorbent) in pure water. Next, Ag/Fe 3 O 4 was applied to the removal of radioiodine, and high removal efficiencies were observed in water. In addition, its desalination capacity was retained in the presence of competitive ions and varied pH. After the adsorption process, Ag/Fe 3 O 4 was easily removed from the water by applying an external magnetic field. Moreover, the same operation can be repeated several times without a significant decrease in the performance of Ag/Fe 3 O 4 . Therefore, it is expected that the findings presented in this study will offer a new method for desalinating radioiodine in various aqueous media. Keywords: adsorbents; radioactive wastes; radioactive iodine; desalination; nanocomposites 1. Introduction The safe and reliable treatment of radioactive waste is inevitably linked to the safe production of nuclear energy [1,2]. Environmental damage caused by radioactive waste has attracted global attention. Radioisotopes, such as radioactive iodine (radioiodine), which exhibit a high degree of dispersion in water and air, are produced by nuclear fission. These can exert long-term adverse effects on human lives [3–5]. Notably, the global con- cern regarding nuclear waste leakage was kindled by the Fukushima accident in 2011 [6]. Further, the Chernobyl disaster in Ukraine occurred in 1986 wherein iodine radioisotopes were a major component of the radioactive contamination [7]. Moreover, the continuous operation of nuclear power plants can produce and introduce trace amounts of radioiodine into the environment [8]. Radioiodine has also been extensively used in the diagnosis of diseases and treatment of thyroid cancer on the basis of the selective uptake of iodine into the thyroid [9,10]. Consequently, the introduction of trace amounts of radioiodine from nuclear medicine research institutes also needs to be considered. For example, the Nanomaterials 2021, 11, 588. https://doi.org/10.3390/nano11030588 https://www.mdpi.com/journal/nanomaterials