Adsorption of scandium and neodymium on biochar derived after low-temperature pyrolysis of sawdustAdsorption of scandium and neodymium on biochar derived after low-temperature pyrolysis of sawdust Peer-Reviewed Journal Publication Δημοσίευση σε Περιοδικό με Κριτές 2018-03-222017enResearch was supported by the European Commission in the frame of Horizon 2020 project “Metal recovery from low-grade ores and wastes”, www.metgrowplus.eu, Grant Agreement Nr 690088The objective of this study was to investigate the adsorption of two rare earth elements (REEs), namely scandium (Sc) and neodymium (Nd), on biochar produced after low temperature pyrolysis (350◦C) of wood sawdust. The biochar was characterized with the use of several analytical techniques, namely X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric (TG) analysis, while the pH at point of zero charge (pHPZC) was also determined. The experimental conditions were: absorbent concentration 1–10 g L−1, REE concentration in solution 20 mg L−1, contact time for equilibrium 24 h, temperature 25◦C and stirring speed 350 rpm. The efficiency of biochar was compared to that of a commercial activated carbon. Geochemical modelling was carried out to determine speciation of Nd and Sc species in aqueous solutions using PHREEQC-3 equipped with the llnl database. The experimental results indicated the potential of low temperature produced biochar, even though inferior to that of activated carbon, to adsorb efficiently both REEs. The equilibrium adsorption data were very well fitted into the Freundlich isotherm model, while kinetic data suggested that the removal of both REEs follows the pseudo-second order kinetic reaction. Finally, the most probable adsorption mechanisms are discussed.Research paperhttp://creativecommons.org/licenses/by-nc-sa/4.0/Minerals7101-18Komnitsas_et_al_Minerals_7(10)_2017.pdfChania [Greece]Library of TUC2018-03-22application/pdf3.5 MBfree Komnitsas Konstantinos Κομνιτσας Κωνσταντινος Zacharaki Dimitra Ζαχαρακη Δημητρα Μπάρτζας Γεώργιος Bartzas Georgios Alevizos Georgios Αλεβιζος Γεωργιος MDPI Activated carbon Adsorption Freundlich model Neodymium Pyrolysis Sawdust-derived biochar Scandium