Synthesis and Investigation of Composite Sorbents Based on Mixed K–Co and K–Cu Ferrocyanides for Cesium Extraction From Aqueous Media

A new method for the fabrication of composite sorbents based on mixed K–Co and K–Cu ferrocyanides using polyethylene was proposed. The unique feature of this method is that hydrophobization of the material is attained by integration of polyethylene fibers into the ferrocyanide structure. The surface morphology and structure of the sorbents were investigated by scanning electron microscopy, powder X-ray diffraction, and low-temperature nitrogen adsorption. Characteristic features of extraction of micro- and macro-concentrations of Cs+ cations and 137Cs radionuclide from sea water under static conditions were studied. The experimental sorption data were approximated using the Langmuir and Freundlich equations, and the maximum sorption Gmax and adsorption equilibrium constants were calculated. The sorbents synthesized with the addition of polyethylene showed the best sorption performance (the removal efficiency of cesium ions from seawater reaches 99%). The average distribution coefficient of cesium in seawater is 3.8 × 104 mL/g for a solid-to-liquid phase ratio of 1000 mL/g. This attests to good prospects of application of these sorbents for removal of radioactive cesium from seawater.