CelloZIFPaper_In situ and CelloZIFPaper_Ex situ after adsorption of Co 2+ show a peak at a binding energy of 782.1 eV referring to Co2p3/2 (Fig. ). The analysis of the adsorbed metal ions indicates that the adsorption takes place via coordination to the carboxylic groups of TOCNF or via electrostatic interaction without any observation of an ion-exchange mechanism. The adsorption of tetrahedral ions such as Cu 2+ or Co 2+ can be coordinated to the functional groups of ZIF-8, including O-H and N-H groups, low-coordinated Zn atoms, and free N -groups belonging to Hmim . Thus, these metals render the recyclability of the materials difficult using the desorption via acetonitrile compared to other metal ions such as Pb 2+ (Figure ). MOFs-based materials are recognized as promising matrices for metal adsorption .