Selective removal of cesium from aqueous solutions with nickel (II) hexacyanoferrate (III) functionalized agricultural residue–walnut shell

•Novel biosorbent for cesium removal was derived from agricultural residue.•It could remove cesium effectively from aqueous solution.•Large size of granules makes it easy to be separated from solutions.•The volume of used biosorbent could be significantly reduced after incineration.•Incinerated biosorbent has a low volume and a low cost final disposal. A novel nickel (II) hexacyanoferrate (III) functionalized agricultural residue-walnut shell (NiIIHCFIII-WS) was developed to selectively remove cesium ion (Cs+) from aqueous solutions. This paper showed the first integral study on Cs+ removal behavior and waste reduction analysis by using biomass adsorption material. The results indicated that the removal process was rapid and reached saturation within 2h. As a special characteristic of NiIIHCFIII-WS, acidic condition was preferred for Cs+ removal, which was useful for extending the application scope of the prepared biomass material in treating acidic radioactive liquid waste. The newly developed NiIIHCFIII-WS could selectively remove Cs+ though the coexisting ions (Na+ and K+ in this study) exhibited negative effects. In addition, approximately 99.8% (in volume) of the liquid waste was reduced by using NiIIHCFIII-WS and furthermore 91.9% (in volume) of the spent biomass material (Cs-NiIIHCFIII-WS) was reduced after incineration (at 500°C for 2h). Due to its relatively high distribution coefficient and significant volume reduction, NiIIHCFIII-WS is expected to be a promising material for Cs+ removal in practice.