Ni(II) adsorption on biochars produced from different types of biomassNi(II) adsorption on biochars produced from different types of biomass Peer-Reviewed Journal Publication Δημοσίευση σε Περιοδικό με Κριτές 2021-08-302020enThis work was financially supported by the project INVALOR: Research Infrastructure for Waste Valorization and Sustainable Management (MIS 5002495) which is implemented under the Action ‘Reinforcement of the Research and Innovation Infrastructure’, funded by the Operational Programme ‘Competitiveness, Entrepreneurship and Innovation’ (NSRF 2014-2020) and co-financed by Greece and the European Union (European Regional Development Fund).The objective of this study was to demonstrate biochar’s effectiveness on Ni(II) removal from aqueous solutions by adsorption on three different biochars. Three different waste feedstocks, namely sewage sludge, exhausted olive pomace and the organic fraction of municipal solid waste, were used to produce biochar through pyrolysis at 300 °C, under inert conditions. The obtained biochars were characterized regarding their main properties and then evaluated as potential Ni(II) adsorbents. All investigated materials showed high adsorption efficiency in the range of 78–97%, with the biochar derived from SS exhibiting the best results, possibly because of its higher cation exchange capacity. Ni(II) removal rates were higher when the adsorption experiments were conducted at natural pH, while the removal efficiency under adjusted pH (acidic or alkaline) was slightly lower. The pseudo-second-order kinetic model adequately described the adsorption kinetics depicting high correlation coefficients, while the Freundlich adsorption isotherm model was successful in simulating equilibrium of adsorption.http://creativecommons.org/licenses/by/4.0/Water, Air, & Soil Pollution2315 Mourgela Rafaila-Nikola Μουργελα Ραφαηλα--Νικολα Regouzas Panagiotis Ρεγκουζας Παναγιωτης Pellera Frantseska-Maria Πελλερα Φραντσεσκα-Μαρια Diamantopoulos Evaggelos Διαμαντοπουλος Ευαγγελος Springer Biochar Nickel Sewage sludge Olive pomace Municipal solid waste