Investigation of adsorptive and catalytic performance of a novel nano-sized amine-modified metal organic framework toward levofloxacin

A Fe-based metal organic framework (Materials Institute Lavoisier: MIL-100(Fe)) with a specific surface area and total pore volume of 1236 m2/g and 0.84 cm3/g was synthesized by an environmentally friendly method at room temperature. To modify the sample with nitrogen-containing groups, aminoisophthalic acid (AIA), with a similar structure to 1,3,5-benzene tricarboxylic acid (BTC: the common ligand of MIL-100(Fe)) but with amine functional groups, was used as an additional ligand. Despite a negative effect on the specific surface area (466 m2/g) and total pore volume (0.60 cm3/g), this modification increased adsorption capacity and rate towards levofloxacin, especially under very acidic conditions. The dark Fenton-like oxidation experiments at pH 3 showed a much higher levofloxacin decomposition rate with the AIA-modified sample and a higher removal percentage (58%) at room temperature. Fe leaching tests showed that the modified sample with AIA has a lower Fe leaching in the range allowed by EU standards (1.8 mg/L). AIA modified sample showed more stable performance with changing the conditions (increasing the temperature (20–50 ℃) and changing the pH). The optimum values for H2O2 concentration and dosage were determined for both cases. The modified MOF at a lower temperature, using lower H2O2 concentration, resulted in the degradation of levofloxacin at a higher rate. It also kept its degradation performance in five successive degradation phases without any regeneration.