Cs$^{+}$ Trapping in Size-Controlled Nanospaces of Hexacyanoferrates

Abstract

We demonstrated that divalent manganese/zinc ions (MnII/ZnII) and ferricyan ion [FeIII(CN)6]3- cooperatively trap the cesium ion in aqueous solution within the self-fabricated cubic nanospace with high efficiency. In the low-Cs+-concentration region (≤100 ppm), addition of 5 mmol/L [Fe(CN)6]3+ and 5 mmol/L MnII/ZnII significantly reduces the Cs+ concentration 0.003/0.008 ppm. In the higher-concentration region, the Cs trapping capacity (T≡MCs/Mhost, where MCs and Mhost are the masses of the trapped cesium and host, respectively) reaches T = 420/410 mg/g above 6 mmol/L. The size matching between the nanospace (5.30/5.20 Å for the Mn/Zn compounds, respectively) and the ionic radius (rCs+ = 1.74 Å) of the guest Cs+ is responsible for the high trapping efficiency.

Limitation of adsorptive penetration of cesium into Prussian blue crystallite

“…7a. Except for the uptake selectivity, essentially similar results have already been reported for PBAs(Moritomo et al 2013;Omura and Moritomo 2012). The formation of Cs-type and K-type PBs is described in the following chemical equations.4a À 3 ð ÞCs þ þ a½FeðIIÞðCNÞ 6 4À þ Fe(III) 3þ !…”

“…uptake during the synthesis of PB, in which the PB framework was not yet built. To the best of our knowledge, this type of experiment was first attempted for PBAs by the immediate precipitation reaction method by Omura et al (Omura and Moritomo 2012). They demonstrated the effectiveness of Cs ?…”

“…. Here, we must mention that PB typically has varying numbers of [Fe(II)(CN) 6 ] 4-vacancies (Buser et al 1977;Herren et al 1980;Ishizaki et al 2013;Louise et al 2013;Omura and Moritomo 2012). As a result, the vacancy is an important factor determining the amount of charge compensation cations, that is, potential adsorption sites; an increase in the vacancy leads to a decrease in the charge compensation cation sites.…”

“…They demonstrated the effectiveness of Cs ? uptake during the synthesis of PBAs (Moritomo et al 2013;Omura and Moritomo 2012). However, the uptake selectivity for Cs ?…”

“…migration was impossible in the crystallite (2013). Other literature has also pointed to the penetration limitation (Omura and Moritomo 2012;Thanapon et al 2010). However, the existing literature lacks quantitative evidence.…”