Efficient removal of piroxicam and ketoprofen by acid-modulated iron(III) metal–organic frameworks

[Display omitted] •A series of modulated MOFs, MIL-126, was used for the removal of pharmaceuticals.•The sample MIL-126-1AA can adsorb piroxicam and ketoprofen with high capacities.•Non-covalent interactions and hydrogen bonding play major roles in the adsorption. Pharmaceutical substances such as piroxicam and ketoprofen have been detected in worldwide water sources, posing an emerging risk to environmental health. Therefore, developing a low-energy and efficient method to remove these pollutants from the environment is necessary. Herein, the adsorption of piroxicam and ketoprofen from water has been investigated by using a series of modulated metal–organic frameworks, namely MIL-126 synthesized in the presence of various amounts of acetic acid. The material synthesized with 1 equivalent of the acid modulator, MIL-126-1AA, has been found to show impressive adsorption activities, irrespective of its lower surface area than the other MOF samples studied. MIL-126-1AA exhibits maximum adsorption capacities of 209.65 mg g−1 for piroxicam and 452.49 mg g−1 for ketoprofen, respectively. Such high adsorption capacities can be attributed to the permanent porosity of MIL-126, an optimal amount of defects, as well as a delicate balance of non-covalent interactions between the MOFs and the adsorbates, as revealed from the adsorption studies and X-ray photoelectron spectroscopic analysis. Additionally, the durability of the adsorbents allows them to be reusable after multiple cycles without significant decrease in the adsorptive performance, further highlighting their potentials for the remediation of pharmaceuticals and other organic pollutants from the environment.