Comment on "Kinetics and thermodynamics of Eu(III) adsorption onto synthetic monoclinic pyrrhotite" by Y. Zhu et al., Journal of Molecular Liquids, 218 (2016), 565-570

The paper of Zhu et al. [1] is of great interest, since it reported adsorption data of Eu(III) onto pyrrhotite, an uninvestigated solid surface to date. We are of the opinion that the system is of relevance in the context of nuclear waste disposal in deep repositories. In the study, Eu(III) is used as an analogue for trivalent actinides and pyrrhotite might be a relevant mineral under reducing conditions. Unfortunately, for readers interested in using the uptake data for developing a surface complexation model, some crucial information concerning experimental conditions is missing and some statements in the text require some clarification. We aim here to raise some relevant questions in a constructive way, to achieve a correct understanding of this interesting data. (C) 2016 Elsevier B.V. All rights reserved.