Sorption separation of Eu and As from single-component systems by Fe-modified biochar: kinetic and equilibrium study

The utilization of carbonaceous materials in separation processes of radionuclides, heavy metals and metalloids represents a burning issue in environmental and waste management. The main objective of this study was to characterize the effect of chemical modification of corncob-derived biochar by Fe-impregnations on sorption efficiency of Eu and As as a model compounds of cationic lanthanides and anionic metalloids. The biochar sample produced in slow pyrolysis process at 500 °C before (BC) and after (IBC) impregnation process was characterized by elemental, FTIR, SEM-EDX analysis to confirm the effectiveness of Fe-impregnation process. The basic physico-chemical properties showed differences in surface area and pH values of BC- and IBC-derived sorbents. Sorption processes of Eu and As by BC and IBC were characterized as a time- and initial concentration of sorbate-dependent processes. The sorption equilibrium was reached for both sorbates in 24 h of contact time. Batch equilibrium experiments revealed the increased maximum sorption capacities (Qmax) of IBC for As about more than 20 times (Qmax BC 0.11 and Qmax IBC 2.26 mg g−1). Our study confirmed negligible effect of Fe-impregnation on sorption capacity of biochar for Eu (Qmax BC 0.89 and Qmax IBC 0.98 mg g−1). The iron-impregnation of biochar-derived sorbents can be utilized as a valuable treatment method to produce stable and more effective sorption materials for various xenobiotics separation from liquid wastes and aqueous solutions.