The positively charged Al 3+ center of MIL-96 is surmised to have a strong interaction with the anionic carboxylate groups (COO -) of PFOA. Contrary to expectations, increasing the eluent ionic strength has minimal effect on PFOA desorption by MIL-96-RHPAM2 except for a slight drop at the highest tested salt concentration (500 mM NaCl). Such salt concentration may be sufficiently high enough to reduce the electrostatic forces between the Al 3+ center and the negatively charged PFOA molecules resulting from the competitive PFOA adsorption with the background ions (Na + and Cl -). However, due to the well-established acid-base and electrostatic bonds between the Al 3+ , carboxylate (COO -), hydroxyl (OH), NH2 and NH3 + functional groups on the MOF, the driving force to establish new bonds with the incoming Na + and Cl -ions is not as favorable, hence, not accommodating the desorption of adsorbed PFOA molecules into the eluent phase.