Adsorption of commercial glyphosate by MOF-808: a new ZrMOF for water purification

This work reports for the first time the use of MOF-808 for the adsorption of glyphosate from a diluted herbicide formulation (Roundup®). MOF-808 was synthesized in organic solvent (MOF-808(DMF)) or in water (MOF-808(H₂O)) to compare the influence of textural characteristics on the adsorption process. In addition, the adsorption performances of these materials were compared to those of the UiO-66 and UiO-66(NH₂) series materials, which have the same SBU, allowing us to evaluate the influence of the topicity and functionalization of the ligand on the adsorption capacity of glyphosate. MOF-808 showed the highest adsorption capacity, reaching a q_max equal to 277.01 mg g⁻¹, and good kinetic performance, removing 70.3% of the glyphosate from solution in 10 min and 99.5% after 3 h of contact. MOFs UiO-66 and UiO-66(NH₂) had lower q_max values than MOF-808, possibly due to the blockage of their narrow pores by GLY, which prevents them from accessing Zr sites. The results showed an important relationship between the hydrodynamic diameter and the pore size distribution with access to active sites, consequently influencing the adsorption performance of these porous materials.