Kinetic features of cesium sorption onto a polyfunctional ferrocyanide sorbent

Abstract

The kinetics of cesium sorption onto mixed nickel potassium ferrocyanide supported on hydrated titanium dioxide were studied in different ranges of cesium concentrations. At the cesium concentration in solution from 2 × 10 -7 to 5 mg L -1 , the sorption rate is determined by external diffusion of cesium ions in solution, heterogeneous ion-exchange reaction, and internal diffusion of cesium in the pore space of the sorbent. The slowest step is the breakdown of sorption colloids and uptake of the released cesium ions by the sorbent. At the cesium concentration in solution higher than 50 mg L -1 , the rate-determining step is the precipitation of mixed nickel cesium ferrocyanide in the pore space of the sorbent.

Mechanism of strontium sorption by the mixed nickel–potassium ferrocyanide based on hydrated titanium dioxide

“…Mechanisms of caesium sorption by the NPF-HTD sorbent are studied and described in works [5,8]; therefore, physicochemical characteristics of samples of the sorbent after caesium sorption were used for comparison. 100 mg samples of the sorbent were used in experiments.…”

“…Mechanisms of caesium sorption by the NPF-HTD are described in the work [5]. The selectivity of strontium sorption from aqueous solutions in the presence of calcium is also described in the work [6].…”

New Sorbents Based on Polyacrylonitrile Fiber and Transition Metal Ferrocyanides for 137Cs Recovery from Various Composition Solutions

“…However, it should be noted that sorbents based on AMP are prone to adsorption of 40 K, which leads to an overestimation of the result of measuring 137 Cs activity; therefore, sorbents based on transition metal ferrocyanides are preferable [4]. Transition metal ferrocyanides can be used to extract 137 Cs in pure form [12] or deposited on a support: PAN fiber (KNiFC-PAN) [4,13,14], silica gel (SiO 2 -KMCHCF [15], FSS [16], FC-Cu-EDA-SAMMS [17]), aluminosilicates (Niket-k) [18,19], chitin-containing materials (FFCG-SO 4 -FC [20], Mikoton-Cs [21], CFC Zn-K, CFC Cu-K, CPC Ni-K [22]), hydrated zirconium dioxide (Thermoxide 35) [16,23,24], activated carbon (C/NiHCFe, C/InHCFe, C/CuHCFe) [25], cellulose support (Anfezh [16,19,26], Uniket [18], NKF-C [27,28], FN and FN-50 [19,29]), natural minerals (diatomite (FND) [19,24], tripolite [30], clinoptilolite (NPF-CL) and quartz-glauconite concentrate (NPF-GL) [23,31,32]) and others. Zeoliteimidazole frameworks [33], mesoporous silica gels [34], aerogels [35], and hydrogels [36], which showed high sorption characteristics in cesium recovery, should be mentioned as new promising supports.…”

“…Most often, natural biopolymers are used in the form of cellulose raw materials. However, it should also be noted that the sorbents obtained from natural cellulose initially contain 137 Cs radionuclides up to 36.3 mBq/g, which complicates their use in the concentration and determination of 137 Cs in environmental objects, including natural waters [31].…”