"Ion-imprinting" strategy towards metal sulfide scavenger enables the highly selective capture of radiocesium

Highly selective capture of radiocesium is an urgent need for environmental radioactive contamination remediation and spent fuel disposal. Herein, a strategy is proposed for construction of "inorganic ion-imprinted adsorbents" with ion recognition-separation capabilities, and a metal sulfide Cs2.33Ga2.33Sn1.67S8·H2O (FJSM-CGTS) with "imprinting effect" on Cs+ is prepared. We show that the K+ activation product of FJSM-CGTS, Cs0.51K1.82Ga2.33Sn1.67S8·H2O (FJMS-KCGTS), can reach adsorption equilibrium for Cs+ within 5 min, with a maximum adsorption capacity of 246.65 mg·g-1. FJMS-KCGTS overcomes the hindrance of Cs+ adsorption by competing ions and realizes highly selective capture of Cs+ in complex environments. It shows successful cleanup for actual 137Cs-liquid-wastes generated during industrial production with removal rates of over 99%. Ion-exchange column filled with FJMS-KCGTS can efficiently treat 540 mL Cs+-containing solutions (31.995 mg·L-1) and generates only 0.12 mL of solid waste, which enables waste solution volume reduction. Single-crystal structural analysis and density functional theory calculations are used to visualize the "ion-imprinting" process and confirm that the "imprinting effect" originates from the spatially confined effect of the framework. This work clearly reveals radiocesium capture mechanism and structure-function relationships that could inspire the development of efficient inorganic adsorbents for selective recognition and separation of key radionuclides.

226Ra and 137Cs determination by inductively coupled plasma mass spectrometry: state of the art and perspectives including sample pretreatment and separation steps

Achieving precise and accurate quantification of radium (²²⁶Ra) and cesium (¹³⁷Cs) by inductively coupled plasma mass spectrometry (ICP-MS) is of particular interest in the field of radiological monitoring and more widely in environmental and biological sciences. However, the accuracy and sensitivity of the quantification depend on the analytical strategy implemented. Eliminating interferences during the sample handling step and/or during the analysis step is critical since presence of matrix elements can lead to spectral and non-spectral interferences in ICP-MS. Consequently, before the ICP-MS analysis, multiple sample preparation approaches have been applied to purify and/or pre-concentrate environmental and biological samples containing radium and cesium through years, such as (co)-precipitation, solid phase extraction (SPE) or dispersive SPE (dSPE). Separation steps using liquid chromatography and capillary electrophoresis can also be useful in complement with the abovementioned sample preparation techniques. The most attractive sample handling technique remains SPE but efficiency of the extraction procedures is currently limited by sorbent specificity. Indeed, with the recent advances in ICP-MS instrumentation, it becomes indispensable to eliminate residual interferences and improve sensitivity. It is in this direction that it will be possible to meet analytical challenges, e.g. analyzing radium and cesium at concentrations below the pg L^-1 range in complex matrices of small volumes, as they are found for instance in pore waters or in biological samples. Development of new innovative sorbents based for example on hybrid and nanostructured materials has been reported with the aim of enhancing sorbent specificity and/or capacity. In the present review, the performances of the different analytical approaches are discussed, followed by an overview of applications.

Ion-Imprinted Polymers: Synthesis, Characterization, and Adsorption of Radionuclides

Growing concern over the hazardous effect of radionuclides on the environment is driving research on mitigation and deposition strategies for radioactive waste management. Currently, there are many techniques used for radionuclides separation from the environment such as ion exchange, solvent extraction, chemical precipitation and adsorption. Adsorbents are the leading area of research and many useful materials are being discovered in this category of radionuclide ion separation. The adsorption technologies lack the ability of selective removal of metal ions from solution. This drawback is eliminated by the use of ion-imprinted polymers, these materials having targeted binding sites for specific ions in the media. In this review article, we present recently published literature about the use of ion-imprinted polymers for the adsorption of 10 important hazardous radionuclides-U, Th, Cs, Sr, Ce, Tc, La, Cr, Ni, Co-found in the nuclear fuel cycle.

Dual Ion-Imprinted Mesoporous Silica for Selective Adsorption of U(VI) and Cs(I) through Multiple Interactions

Separation of uranium and cesium from low-level radioactive effluents (LLRE) is of great significance for sustainable development of the nuclear industry and for the environment. However, high salinity and massive coexisting ions of LLRE are giant challenges for the separation. To address the challenges, we report a strategy for efficient and simultaneous separation of uranium and cesium from a high-salt environment by dual ion-imprinted mesoporous silica based on multiple interactions. The as-prepared adsorbents can reach equilibrium for uranium and cesium within 1 h with a maximum capacity of 221.7 mg U g^-1 and 34.5 mg Cs g^-1. The sorption mechanism demonstrates that the highly active phenolic hydroxyl groups of imprinted cavities can extract uranium and cesium effectively through multiple interactions, including coulomb attraction, redox, ion exchange, and complexation. The synergism of multiple interactions and imprinted cavity endows the sorbent with good selectivity for uranium and cesium over other cations and with excellent salt tolerance. This work demonstrates a new strategy of selective extraction of nuclides by multifunction adsorbent through multiple interactions.

Ion-Imprinted Mesoporous Silica for Selective Removal of Uranium from Highly Acidic and Radioactive Effluent

It is strategically important to recycle uranium from radioactive liquid wastes for future uranium supply of nuclear energy. However, it is still a challenge to adsorb uranium selectively from highly acidic and radioactive waste. In this paper, we report a novel strategy for effective uranium removal from highly acidic and radioactive media by surface ion-imprinted mesoporous silica sorbent. The sorbent was successfully synthesized by a co-condensation method with uranyl as the template ion and diethylphosphatoethyltriethoxysilane as the functional ligands. The pseudo-second-order model and Langmuir model showed better correlation with the sorption kinetic and isotherm data, and the sorption equilibrium could be reached within 40 min, the maximum adsorption capacity from Langmuir model was 80 mg/g in 1 mol/L nitric acid (HNO₃) solution at 298.15 K. The sorbent showed faster kinetics and higher selectivity toward uranium over other ions compared with nonimprinted mesoporous and other previous sorbents. Furthermore, the ion-imprinted materials exhibited remarkable radioresistance stability and could be regenerated efficiently after five cycles. This work may provide a new approach for highly efficient sorption of uranium from strong HNO₃ and radioactive media.

γ-Radiation fabrication of porous permutite/carbon nanobeads/alginic acid nanocomposites and their adsorption properties for Cs+

Novel porous permutite/carbon nanobeads/alginic acid nanocomposites were successfully fabricated and applied for Cs⁺ removal.

Preparation of core–shell ion imprinted nanoparticles via photoinitiated polymerization at ambient temperature for dynamic removal of cobalt in aqueous solution

In this work, novel core–shell ion imprinted polymers were firstly synthesized by photoinitiated polymerization (P-IIPs) for the selective separation of Co(ii) in aqueous solution.