Eco-friendly one-pot synthesis of Prussian blue-embedded magnetic hydrogel beads for the removal of cesium from water

Hee-Man Yang,Kune-Woo Lee,Chan Woo Park,Dong Yeop Lee,Ju Ri Hwang,Hee Reyoung Kim,Kyu Beom Kim

doi:10.1038/s41598-018-29767-y

Abstract

A simple one-step approach to fabricating Prussian blue-embedded magnetic hydrogel beads (PB-MHBs) was fabricated for the effective magnetic removal of radioactive cesium (137Cs) from water. Through the simple dropwise addition of a mixed aqueous solution of iron salts, commercial PB and polyvinyl alcohol (PVA) to an ammonium hydroxide (NH4OH) solution, the formation of hydrogel beads and the encapsulation of PB in beads were achieved in one pot through the gelation of PVA with in situ-formed iron oxide nanoparticles as the cross-linker. The obtained PB-MHBs, with 43.77 weight % of PB, were stable without releasing PB for up to 2 weeks and could be effectively separated from aqueous solutions by an external magnetic field, which is convenient for the large-scale treatment of Cs-contaminated water. Detailed Cs adsorption studies revealed that the adsorption isotherms and kinetics could be effectively described by the Langmuir isotherm model and the pseudo-second-order model, respectively. Most importantly, the PB-MHBs exhibited excellent selectivity for 137Cs in 137Cs-contaminated simulated groundwater (55 Bq/g) with a high removal efficiency (>99.5%), and the effective removal of 137Cs from real seawater by these PB-MHBs demonstrated the excellent potential of this material for practical application in the decontamination of 137Cs-contaminated seawater.

Highlights

Due to increased energy demands and concern about global warming, inexpensive and carbon-free nuclear power has been proposed as an alternative to thermal power derived from fossil fuels[1]
The PB-embedded magnetic hydrogel beads (PB-MHBs) were fabricated by the facile dropwise addition of a mixed aqueous solution of iron salts, commercial PB and polyvinyl alcohol (PVA) to an ammonium hydroxide (NH4OH) solution
The X-ray powder diffraction (XRD) pattern obtained from the PB-MHBs fabricated at pH values of 11.3, 11.4, and 11.5 exhibited the characteristic peaks of both PB and Fe3O4, indicating the successful formation of magnetic particles and encapsulation of PB in the hydrogel beads (Fig. S2)

Summary

Introduction

Due to increased energy demands and concern about global warming, inexpensive and carbon-free nuclear power has been proposed as an alternative to thermal power derived from fossil fuels[1]. The other approach is to use magnetic particles to magnetically separate the adsorbent after 137Cs sorption In such methods, various metal hexacyanoferrates, including PB, were coated on the surface of magnetic nanoparticles (MNPs) using functional coating materials[24,25,26]. During the formation of the PVA-iron oxide nanoparticle-based hydrogel bead, the commercial PB was encapsulated in the hydrogel network, resulting in the facile generation of MHBs containing PB as a Cs adsorbent These PB-MHBs prepared using our one-pot method are suitable for practical applications because the synthetic strategy is scalable under ambient conditions and uses only eco-friendly and low-cost precursors

Methods

Results

Conclusion