Efficient separation of strontium radionuclides from high-salinity wastewater by zeolite 4A synthesized from Bayer process liquids

Abstract

The efficient, selective, and economical sorbents for the removal of Sr radionuclides are largely needed for the decontamination of effluents with high salinity. In this study, the removal of Sr was investigated using the zeolite produced from the Bayer process liquids. Based on the XRD, SEM/EDS analysis, the product was pure and highly crystalline zeolite 4A (Z4A). Removal of Sr was fast (5 min for 100% removal at 8.80 mg/L), with high maximum sorption capacity (252.5 mg/L), and independent on the initial pH in the range 3.5–9.0. Specific sorption of Sr by protonated groups on the Z4A surface was operating in addition to ion-exchange with Na ions. The selectivity of Z4A decreased in the order Sr > Ca > K > Mg > Na. 84% of Sr was separated from seawater within 5 min, at the Z4A dose of 5 g/L, while efficiency increased to 99% using the dose of 20 g/L. Desorption of radioisotope 89Sr from seawater/Z4A solid residue was very low in deionized water (0.1–0.2%) and groundwater (0.7%) during 60 days of leaching. Z4A is a cost-effective, selective, and high-capacity medium for Sr removal, which provides high stability of retained radionuclides.

Selective radionuclide and heavy metal sorption using functionalised magnetic nanoparticles for environmental remediation

“…Optimal extraction environments for these metal ions are known to be above pH 6, where studies conducted previously show their reduced effectiveness below this pH value. 9,49–51 Overall there was little effect when decreasing the pH on the sorption and loading capacities of the NP complexes. Due to the observed rapid dissolution of (PO) x -Fe 3 O 4 NPs at this pH, they were not tested and therefore only tested in high pH environments (pH 11).…”

Utilization of carbon-coated ZrO2/Mn-Mg-Zn ferrites nanostructures for the adsorption of Cs (I) and Sr (II) from the binary system: kinetic and equilibrium studies

“…These radionuclides release significant beta energy with a maximum value of 2.28 MeV. Zirconium-90, a stable isotope, results from 90 Y decay [ 10 , 11 ]. Many strategies for removing radionuclides from the waste stream have been used, including ion exchange [ 11 ], chemical precipitation, membrane filtering [ 10 ], solvent extraction [ 12 , 13 ], and adsorption [ 4 ].…”

“…Zirconium-90, a stable isotope, results from 90 Y decay [ 10 , 11 ]. Many strategies for removing radionuclides from the waste stream have been used, including ion exchange [ 11 ], chemical precipitation, membrane filtering [ 10 ], solvent extraction [ 12 , 13 ], and adsorption [ 4 ]. Each technique has benefits and drawbacks depending on process efficiency, ease of use, cost, and flexibility.…”

Origin of the exceptional selectivity of NaA zeolite for the radioactive isotope 90Sr2+

“…Various organic and inorganic absorbents have been employed to remove 90 Sr 2+ , including resins, 27,28 activated carbon, 29 natural minerals, 30,31 zeolites, 32,33 metal–organic frameworks (MOFs), 34,35 covalent organic frameworks (COFs), 36 etc . Compared with organic/polymer-based ion exchangers, inorganic ion exchangers are more affordable for large-scale applications.…”

“…19 Because the concentration of 90 Sr 2+ is extremely low in nuclear wastewater, either adsorption via ion exchange or extraction with a strong binding site to 90 Sr 2+ is the most efficient and energy-saving method. 1,[20][21][22][23][24][25][26] Various organic and inorganic absorbents have been employed to remove 90 Sr 2+ , including resins, 27,28 activated carbon, 29 natural minerals, 30,31 zeolites, 32,33 metal-organic frameworks (MOFs), 34,35 covalent organic frameworks (COFs), 36 etc. Compared with organic/polymer-based ion exchangers, inorganic ion exchangers are more affordable for large-scale applications.…”