New Sorbents Based on Polyacrylonitrile Fiber and Transition Metal Ferrocyanides for ¹³⁷Cs Recovery from Various Composition Solutions

Featured Application New sorbents based on polyacrylonitrile fiber and transition metal ferrocyanides can be used for Cs-137 selective sorption from technological solutions (liquid low- and intermediate-level waste; seawater containing radioactive waste; wastewater), as well as from natural waters (fresh and saltwater) with the purpose of radioecological monitoring. For the first time, new sorbents based on polyacrylonitrile (PAN) fiber and transition metal ferrocyanides were obtained. The main difference between the obtained sorbents and the existing ones is the stage of preliminary preparation of the initial support by converting it into the forms PAN-Fe(OH)(3) or PAN-MnO2, due to which additional ion exchange groups (carboxyl, carbonyl, etc.) are formed, which increases the amount of ferrocyanide fixed to the support. The best components and conditions for the synthesis of new sorbents were determined (concentration (0.1-0.2 mol/L), as well as pH (1 for sorbents based on PAN-Fe(OH)(3), and 1-5-PAN-MnO2) of potassium ferrocyanide solution, concentration of transition metal salts (0.02 mol/L), temperature conditions). The influence of the studied solution composition (pH, concentration of Na+, K+, NH4+ ions) on the cesium distribution coefficients during its recovery by the obtained sorbents was assessed. The possibility of cesium recovery from solutions with pH 1-9 containing macro quantities of cations was demonstrated. The sorbents derived were characterized by modern structural methods such as infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy with EDS analysis. A study of the trace amount sorption of Cs-137 was carried out in comparison with commercially available highly efficient sorbents (FNS-10 and Termoksid-35), and it was shown that the resulting sorbents are not inferior to industrial ferrocyanide sorbents and can be used for Cs-137 selective sorption from technological solutions and natural waters.