Preparation and characterization of potassium nickel hexacyanoferrate-loaded hydrogel beads for the removal of cesium ions

Abstract

A novel synthetic approach has been used to prepare sorbent hydrogel composite beads of potassium nickel hexacyanoferrate (KNiHCF), using PVA and cross-linked alginate as the binding matrix. The characterization study indicates the high hydrophilicity and high surface area of the synthesized beads. The application potential of these beads for removal of cesium ions from low level liquid nuclear waste has been studied in batch mode using a 137 Cs radiotracer. The equilibrium sorption and kinetic data are obtained at different initial cesium ion concentrations. These data are analysed using various sorption isotherm and kinetic models. It is observed that the sorption process can be best described by the Langmuir isotherm model, and the monolayer capacity of the beads is determined to be 7 mg per g of the swollen beads, which corresponds to~64 mg per g of the dry beads. The sorption of cesium ions onto the sorbent beads is found to follow pseudo second-order kinetics over the entire studied concentration range. The ion-exchange mechanism involves the exchange of cesium ions with potassium ions. The mechanism of the sorption process is also investigated using the intraparticle diffusion model and Boyd's plot, and the results indicate that the sorption of cesium ions onto the beads is a complex process, involving both intraparticle diffusion and film diffusion.

Solvent-assisted synthesis of potassium copper hexacyanoferrate embedded 3D-interconnected porous hydrogel for highly selective and rapid cesium ion removal

“…In order to address such issues, numerous studies have considered the immobilization of the small sized metal HCF particles, either by grafting onto porous media [5,16,20,22], or encapsulating in a polymer matrix [1,3,23,24]. Turgis et al…”

“…For this purpose, poly(vinyl alcohol) (PVA) and citric acid were utilized as the polymer backbone and crosslinking agent due to their low cost, nontoxicity, and hydrophilic properties [25,26]. In addition, the components have abundant oxygen functionalities such as hydroxyl or carboxyl groups which can coordinate metal ions for anchoring and distribution of KCuHCF particles [23,26]. The HPC was synthesized using a two-step procedure ( Fig.…”

“…1(b)). The first step was used to immobilize and distribute Cu in the CPC film structure using the abundant oxygen functional groups in PVA and citric acid [23]. Next, both acetone-treatment and heat-treatment were used according to the conditions presented in Table 1.…”

Highly effective Cs+ removal by turbidity-free potassium copper hexacyanoferrate-immobilized magnetic hydrogels

“…In the current study, potassium copper HCF (KCuHCF) and Fe3O4 immobilized Poly(vinyl alcohol) (PVA) magnetic hydrogel adsorbent (MHPVA) was successfully synthesized via a facile two step method ( Fig.1). PVA was used as a hydrogel backbone, which has abundant hydroxyl groups coordinating metal ions [30]. Moreover, citric acid functionalized Fe3O4 (c-Fe3O4) was used to prevent particle aggregation and to improve the dispersion of KCuHCF nanoparticles.…”

Improved adsorption properties of granulated copper hexacyanoferrate with multi-scale porous networks

“…Therefore, many researchers have reported various materials immobilizing nanoparticles on lter matrixes with binders such as organic and inorganic polymers. [19][20][21][22][23][24] In such cases, because the binder oen obstructs the liquid-gas ow path and covers the adsorbent surface, the adsorption rate tends to be lower because of lower accessibility or contact probability between the adsorbent and adsorbed substance (gas or liquid, etc.). Therefore, for improvement of the sorption rate, tuning of the porous structure including the matrix is important to raise permeability.…”