The Impact of pH and Ion Exchange on 133Cs Adsorption on Vermiculite

Enhanced removal of cesium from hydrobiotite using polyacrylonitrile (PAN)-based nickel ferrocyanide beads

The desorption of cesium (Cs) from contaminated clay minerals remains challenging because of the restricted efficiency of the removal process. Therefore, in the present study, a bead-type adsorbent was added during the conventional acid washing process to improve the removal of Cs⁺ from a clay mineral. As the Cs⁺ adsorbent, polyacrylonitrile-based nickel potassium hexacyanoferrate (NiFC-PAN) was used to selectively adsorb Cs⁺ in a strongly acidic solution containing competing ions. To prevent erosion of the adsorbent under harsh environmental conditions and to facilitate the separation of clay particles, PAN was deliberately constructed as large beads. The synthesized adsorbent (NiFC/PAN in a 2:1 ratio) showed high selectivity for Cs⁺, with a maximum capacity for Cs⁺ adsorption of 162.78 mg/g in 0.5 M HNO₃ solution. Because the NiFC-PAN demonstrated greater Cs⁺ selectivity than the clay mineral (hydrobiotite, HBT), the addition of NiFC-PAN during the acid washing significantly increased Cs⁺ desorption (73.3%) by inhibiting the re-adsorption of Cs⁺ on the HBT. The radioactivity of ¹³⁷Cs-HBT was substantially decreased from 209 to 27 Bq/g by the acid treatment in the presence of NiFC-PAN, corresponding to a desorption efficiency of 87.1%. Therefore, these results suggest that the proposed technique is a potentially useful and effective method for decontamination of radioactive clay.

Comparing Cs+ binding affinity of Keggin type polyoxometalate and sodium Tetrakis(4-florophenyl)borate in solution and from Cs-doped pure phase vermiculite

We assessed the aptitude of cesium (Cs⁺) binding by Keggin type polyoxometalates (POMs) and compared the results with the Cs⁺ binding by sodium tetrakis(4-fluorophenyl)-borate (Na-TFPB). In this work, we aimed to establish a system to treat radioactive Cs⁺ contaminated soil with POMs economically. We evaluated the effect of initial Cs⁺ concentration (0.1M) and precipitant (POMs and TFPB) concentrations (0.01M) on Cs⁺ precipitation. Our comparison of Cs⁺ precipitation by three different POMs and TFPB was obtained by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). We synthesized POMs molybdovanadophosphoric acid, H₅PMo₁₀V₂O₄₀ (MVPA), and silicotungstic acid, H₄SiW₁₂O₄₀ (STA), and used commercially available phosphotungstic acid, H₃PW₁₂O₄₀ (PTA), and TFPB. Cs-doped pure phase vermiculite was also used to demonstrate the extraction potential of Cs⁺ by TFPB, STA, and PTA. All the POMs and corresponding Cs-bound POMs were characterized by UV-visible spectroscopy, Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and X-ray powder diffraction (XRD). In this simulation study, we demonstrated that the Cs⁺ removal by POMs is much more effective than TFPB and could be a promising method for the treatment of radiocesium contaminated soil.

Soil Chemistry and the One Health Initiative: Introduction to the Special Section

Population growth and technical and social changes have always exerted pressure on environmental quality. However, we are experiencing unprecedented change in the rate and scale of human impacts on the environment. The One Health Initiative recognizes that improving the quality of life for humans and other animal species requires a holistic and integrated framework to seek multidisciplinary solutions to global environmental quality challenges. This special section is designed to elucidate the connections among soil health, environmental quality, food safety and security, and human health. Soil chemistry is defined as the field of soil science that deals with the chemical constituents, properties, and reactions of soils. Soil chemistry plays a central role in food production and the protection of human health. Chemical reactions between nutrients or contaminants and soil solids, and the composition of the soil solution and the atmosphere, influence crop growth as well as the quality of our food, air, and water. This collection of nine papers brings together studies that highlight how soil chemical constituents, properties, and reactions can be examined or managed using a multidisciplinary approach to move toward a more efficient, sustainable, nutrient-rich, and low-contaminant food production system that affords protection of soil, water, and human and animal health. We believe that studies such as these are needed to maintain and enhance environmental quality through interdisciplinary scientific approaches for human, animal, and environmental health outcomes.