Effective ¹³⁷Cs⁺ and ⁹⁰Sr²⁺ immobilisation from groundwater by inorganic polymer resin Clevasol® embedded within a macroporous cryogel host matrix

Accepted/In Press date: 30 June 2022

e-pub ahead of print date: 6 July 2022

Published date: November 2022

Additional Information: Funding Information: We thank ADePhine GmbH (Bern, Switzerland) for supplying the Clevasol® resin for our testing. D Berillo acknowledges the European Union's Horizon 2020 Research and Innovation Programme (under the Marie Skłodowska-Curie Fellowship grant agreement 701289) which supported time when writing this paper. A B Cundy, P E Warwick and J M Purkis acknowledge funding from the TRANSCEND (TRANsformative SCience and Engineering for Nuclear Decommissioning) consortium ( EPSRC grant number EP /S01019X/1). We thank three peer reviewers for improving the manuscript through their comments. Funding Information: Column experiments were performed to determine breakthrough curves for Cs and Sr in a simulated in-situ scenario, whereby contaminated groundwater would flow through the Clevasol®-PVACC in one direction. A closed system was assembled as per Fig. SI IV in the Supporting Information, whereby a Gilson Minipuls 3 peristaltic pump set to 0.09 rpm delivered the stable Cs or Sr influent solution constantly at 1.60–1.65 cm3/h through the column. This flow is within the range of the Quaternary Upper aquifer at Sellafield [57]. Samples were collected at the base of the column throughout the experiment by a modified Redirac LKB 2112 fraction collector. The column (7 mm diameter x 58 mm length) was wet packed with Fisher Chemicals Extra Pure sand. System flow was visually verified using Bromocresol green, and the absence of Cs and Sr sorption onto the sand was confirmed by passing influent through the column when only packed with sand. The experiment was then run with a 1 mm layer of Clevasol®, of mass between 37.4 and 39.6 mg, at the base below the sand. Influent solutions contained stable Sr or Cs at a concentration of 20 ppm, made by dissolving CsCl or SrCl2·6H2O in Milli-Q H2O or SGS. Sr samples were measured using a Thermo Scientific CAP 6000 series ICP-OES. Cs samples were measured with an Agilent 8800 Triple Quad ICP-MS, with samples diluted in 2.5% HNO3 with a 5 ppb internal Re standard and using a peristaltic pump at 1 mL/min.The incorporation of Clevasol® particles in the Clevasol®-PVACC significantly reduces SSA relative to blank PVA-based cryogel without particles (Table 1). Using the reported materials and methodology herein, we found the blank PVA-based cryogel to have a significantly higher SSA than previously reported (∼130 vs ∼60 m2/g [53]); we attribute this most probably to variations in molecular weight and deacetylation levels between PVA brands [58]. Previously, we reported cryogels based on CHI-polyelectrolyte complexes which also possess an internal mesoporous structure [59]; SSA of the cryogels presented in Table 1 are comparable to CHI-based functionalised cryogels based on CHI-GA with Pd or Au nanoparticles [50,52]. Clevasol®-PVACC had a higher Young's modulus (Table 1) and demonstrated better resistance to strain (Fig. SI VI in the Supporting Information) than the blank PVA cryogel, demonstrating that the incorporation of the Clevasol® particles into the PVA-based cryogel significantly increased the durability of the material. This is a beneficial trait for practical environmental application within PRBs. Functionalising a PVA-based cryogel with other fine-grained sorbent particles could possibly therefore also potentially enhance the structural integrity of the composite material relative to the blank material, which is promising for future research using PVA-based cryogels as a host matrix. Our additional testing to investigate the potential of CHI as an alternative polymer to PVA showed that the blank CHI-based cryogel had a higher rigidity than the PVA-based cryogel (i.e. undergoing lower strain at higher stresses, Fig. SI VI in the Supporting Information), indicating that it likely has a much higher resistance to hydrostatic pressure. However, this could equally indicate that CHI-based cryogels may be more brittle than PVA-based cryogels. Further research could therefore focus on the optimisation of the synthesis of cryogel-sorbent composites, including exploring the effects of particle incorporation into CHI-based cryogels.We thank ADePhine GmbH (Bern, Switzerland) for supplying the Clevasol® resin for our testing. D Berillo acknowledges the European Union's Horizon 2020 Research and Innovation Programme (under the Marie Skłodowska-Curie Fellowship grant agreement 701289) which supported time when writing this paper. A B Cundy, P E Warwick and J M Purkis acknowledge funding from the TRANSCEND (TRANsformative SCience and Engineering for Nuclear Decommissioning) consortium (EPSRC grant number EP/S01019X/1). We thank three peer reviewers for improving the manuscript through their comments. Publisher Copyright: © 2022 The Author(s)

Keywords: Cesium/cesium, Environmental radioactivity, Radionuclides, Remediation, Sellafield, Strontium

Local EPrints ID: 470485

URI: http://eprints.soton.ac.uk/id/eprint/470485

DOI: doi:10.1016/j.mtsust.2022.100190

PURE UUID: 093f226c-90d2-46f2-8a60-2ec9309804d5

ORCID for J. M. Purkis: orcid.org/0000-0002-6387-1220

ORCID for P. E. Warwick: orcid.org/0000-0001-8774-5125

ORCID for A. B. Cundy: orcid.org/0000-0003-4368-2569

Date deposited: 11 Oct 2022 16:51

Last modified: 18 Mar 2024 03:32