Cesium ion adsorption and desorption on electrospun mesoporous silica nanofibers immobilized with Prussian blue

To fabricate an efficient Cs ion adsorbent and prevent unexpected loss of Prussian blue (PB) colloidal particles during use, PB was immobilized on the surface of electrospun mesoporous silica nanofibers (MSFs) via a newly developed method of double exposure to Fe (III) ions. To introduce PB on MSFs, the MSFs were functionalized with ethylenediamine moiety to bind to Fe (III) ions, which would firmly anchor PB. MSFs were pretreated with Fe (III) ions and exposed to K₄ [Fe(II) (CN)₆] to form PB. We found that this process did not provide a sufficient PB amount on the MSFs. To increase the PB amount, after initial PB formation, the MSFs were treated with Fe (III) ions again so that the unreacted K₄ [Fe(II) (CN)₆] remaining on the MSFs could become PB. An investigation of the adsorption isotherms and kinetics of the nanofibrous adsorbent indicated that monolayer chemisorption had occurred. The maximum Cs ion adsorption capacity using the method of double exposure to Fe (III) ions was determined to be 14.66 mg/g, which was higher by a factor of 2.24 than the case that was not prepared by this method. Cs ions were selectively adsorbed over other cations and could be removed in both acidic and basic conditions, presumably because of the robust MSFs.