Nanocomposite adsorbent based on polyacrylonitrile fibers for rapid and selective removal of Cs radionuclides

Amino modified nanofibers anchored to Prussian blue nanoparticles selectively remove Cs+ from water

To improve the selective separation performance of silica nanofibers (SiO2 NFs) for cesium ions (Cs+) and overcome the defects of Prussian blue nanoparticles (PB NPs), PB/SiO2-NH2 NFs were prepared to remove Cs+ from water. Among them, 3-aminopropyltriethoxysilane (APTES) underwent an alkylation reaction with SiO2, resulting in the formation of a dense Si-O-Si network structure that decorated the surface of SiO2 NFs. Meanwhile, the amino functional groups in APTES combined with Fe3+ and then reacted with Fe2+ to form PB NPs, which anchored firmly on the aminoated SiO2 NFs surface. In our experiment, the maximum adsorption capacity of PB/SiO2-NH2 NFs was 111.38 mg/g, which was 31.5 mg/g higher than that of SiO2 NFs. At the same time, after the fifth cycle, the removal rate of Cs+ by PB/SiO2-NH2 NFs adsorbent was 75.36% ± 3.69%. In addition, the adsorption isotherms and adsorption kinetics of PB/SiO2-NH2 NFs were combined with the Freundlich model and the quasi-two-stage fitting model, respectively. Further mechanism analysis showed that the bond between PB/SiO2-NH2 NFs and Cs+ was mainly a synergistic action of ion exchange, electrostatic adsorption and membrane separation.

Estimation of 137Cs Distribution and Recovery Using Various Types of Sorbents in the Black Sea Surface Layer

Monitoring 137Cs in seawater is necessary for the timely detection of radioactive contamination. The possibility of sorption and the sorption efficiency of 137Cs from seawater were studied for the first time during several cruises of the R/V (research vessel) Professor Vodyanitsky using various types of sorbents based on transition metal ferrocyanides (Anfezh, Niket, Uniket, FSS, FD-M, FIC, Termoxid 35, NKF-C) and zirconium phosphate (Termoxid 3A). The influence of the seawater flow rate and volume of the sorbent used for the recovery of 137Cs was estimated. The ferrocyanide sorbents Niket, Uniket, Termoxid 35, and FIC showed the best sorption efficiency (60–100%) at a seawater flow rate of 2–4 column volumes per minute. The data obtained during three cruises on the R/V Professor Vodyanitsky were analyzed. A detailed (28 sampling points) spatial distribution of 137Cs in the Black Sea along the southern coast of Crimea was studied using the sorbents that showed the best characteristics. An increase in 137Cs activity in the study area was not found, and the average activity was 9.01 ± 0.87 Bq/m3.

Separation and Removal of Radionuclide Cesium from Water by Biodegradable Magnetic Prussian Blue Nanospheres

As the main component of radioactive wastewater, the cesium ion has seriously endangered the environment and human health. Prussian blue nanoparticles (PB NPs) are used as adsorbents for the purification of cesium-containing wastewater because of their ability to selectively adsorb cesium ions. In this work, novel magnetic Prussian blue nanospheres (MPBNs) were developed from polylactic acid nanospheres as a carrier, loaded with Fe3O4 nanoparticles (Fe3O4 NPs) inside and PB NPs outside for the removal of cesium ions with the help of magnetic separation. Meanwhile, the effects on the adsorption efficiency of MPBNs, such as pH, time, temperature and initial concentration of cesium ion solution, were studied. The adsorption isotherms, kinetic models and adsorption thermodynamics were investigated to research the absorption mechanism. The results showed that MPBNs were spherical with a rough surface, and their particle size, iron content and saturation magnetization were 268.2 ± 1.4 nm, 40.01% and 41.71 emu/g, which can be recovered by magnetic separation. At 293 K, MPBNs could reduce the cesium ion solution from 40 mg/L to 4.8 mg/L, and its cesium ion removal rate and adsorption capacity were 82.46% and 16.49 mg/g, respectively. The optimum pH of MPBNs for cesium ion adsorption was 5~9, the adsorption equilibrium time was 60 min, and the maximum adsorption capacity was 17.03 mg/g. In addition, MPBNs were separated rapidly by an external magnetic field, and the adsorption process was an endothermic reaction. The adsorption isotherm and kinetics of MPBNs were in accordance with the Freundlich model and quasi-second-order fitting model, respectively, and the adsorption process of MPBNs was controlled by the diffusion step in particles. Notably, these MPBNs could be effectively separated from water by a magnetic field, facilitating engineering applications in cesium-containing wastewater.

The Sorbents Based on Acrylic Fiber Impregnated by Iron Hydroxide (III): Production Methods, Properties, Application in Oceanographic Research

Sorbents based on Fe(OH)3 and aluminum oxide are widely used in oceanology for the recovery of cosmogenic radionuclides 7Be, 32Si, 32P, and 33P from the seawater. It is also possible to use them for the recovery of the natural radionuclides 210Pb, 234Th. A comparative study of the sorbents based on Fe(OH)3 and acrylic fiber obtained through various impregnation methods was carried out, and their comparison with granulated aluminum oxide. The possibility of extracting trace amounts of phosphorus and beryllium under laboratory and field conditions with these sorbents was studied. The sorption of 7Be, 210Pb, and 234Th on the natural content by the two-column method was investigated. It is shown that fiber samples obtained by oxidation with sodium ferrate and the “classical” method have the highest sorption characteristics.