BTEX removal from aqueous solution with hydrophobic Zr metal organic frameworks.

The Zr based metal organic framework, UiO-66, has been synthesized along with its isostructural equivalence tetrafluorinated, the UiO-66-F4. The corresponding ligands to these MOFs are the widely used BDC (1,4-benzenedicarboxylic acid) and the TFBDC (2,3,5,6-Tetrafluoro-1,4-benzenedicarboxylic acid). These coordination materials have been tested towards the sorption of the organic pollutants (Benzene, Toluene, Ethylbenzene and Xylene) in aqueous phase and both materials showed capacities to adsorb all the pollutants. It has been possible to compare the efficiency in the adsorption of two iso-structural MOFs, which will behave differently due to the hydrophobic behavior of the UiO-66-F4 MOF. The addition of F in the structure of the ligand of the MOF allows to obtain a hydrophobic material by changing the nature of the interactions between the adsorbent and the adsorbate from π-π stacking in the pristine UiO-66 to hydrophobic interactions in the UiO-66-F4. However, size of the pores has also revealed an important effect, since steric impediments will decrease the capacity of the fluorinated MOF towards the sorption of bigger molecules.