A novel nickel (II) hexacyanoferrate (III) functionalized agricultural residue-walnut shell ((NiHCFII)-H-II-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 2 h. As a special characteristic of (NiHCFIII)-H-II-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 (NiHCFIII)-H-II-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 (NiHCFIII)-H-II-WS and furthermore 91.9% (in volume) of the spent biomass material (Cs-(NiHCFIII)-H-II-WS) was reduced after incineration (at 500 C for 2 h). Due to its relatively high distribution coefficient and significant volume reduction, (NiHCFIII)-H-II-WS is expected to be a promising material for Cs+ removal in practice. (C) 2014 Elsevier B.V. All rights reserved.