Contents lists available at ScienceDirect Chemical Engineering Journal journal homepage: www.elsevier.com/locate/cej Selective adsorption of cesium from an aqueous solution by a montmorillonite-prussian blue hybrid Husnul Aulia Alamudy, Kuk Cho ⁎ Department of Environmental Engineering, Pusan National University, 2 Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan 46241, South Korea HIGHLIGHTS • We synthesized montmorillonite- prussian blue adsorbent for the first time. • Its maximum adsorption capacity for cesium was 57.47 mg/g. • Its cesium selectivity is higher than that of most previously reported ad- sorbents. • Potassium cation prevents cesium ad- sorption at 0.01 M concentration or above. • Cesium adsorption occurred through both chemisorption and physisorption. GRAPHICAL ABSTRACT ARTICLE INFO Keywords: Caesium Sorption Removal Radionuclide Distribution coefficient ABSTRACT Cesium generated from nuclear power plants is the primary source of problems for human health and en- vironment due to its gamma radiation and high fission yield. Among the cesium removal methods, adsorption is an effective way to separating it from water. The abundance, retrievability, and selectivity of an adsorbent are crucial for its practical application in wide areas. Herein, we report a simple and environment-friendly synthesis of montmorillonite-prussian blue (MMT-PB) hybrid adsorbents and studies of the kinetic and equilibrium ad- sorption. Even though chemisorption (ion exchange) was dominant, physisorption (ion trapping) also occurred especially for the MMT-PB hybrid. The maximum adsorption capacity of MMT-PB was 57.47 mg/g, which was high enough as compared favorably with that of previously reported adsorbents. The distribution coefficient (K d ) of the hybrid was examined in the presence of prevalent cations such as Na + ,K + , Ca 2+ , and Mg 2+ to analyze its selectivity. The K d value ranged from 3680 to 13700 mL/g at a cation concentration of 0.001 M. Moreover, the divalent cations prevented cesium adsorption due to its high electrostatic interactions with the adsorbent. The K d decreased, ranging from 973 to 4160 mL/g, at a cation concentration of 0.1 M. In this case, K + significantly prevented cesium adsorption as their hydrated radii are similar. Considering the low concentration of K + in nature, the MMT-PB hybrid shows great promise for large-scale application in cesium removal from soil and contaminated water. 1. Introduction From 1985 to 2016, the global electrical power demand of nuclear power plants increased from 245,779 MW to 391,116 MW [1]. The high demand in nuclear power plants has caused serious problems of radionuclide contamination in soils and water. Nuclear power plants https://doi.org/10.1016/j.cej.2018.05.137 Received 28 February 2018; Received in revised form 21 May 2018; Accepted 22 May 2018 ⁎ Corresponding author. E-mail address: kukcho@pusan.ac.kr (K. Cho). Chemical Engineering Journal 349 (2018) 595–602 Available online 23 May 2018 1385-8947/ © 2018 Elsevier B.V. All rights reserved. T