Non-steroidal anti-inflammatory drugs adsorption from aqueous solution by MOFs MIL-100(Fe), ZIF-8 and UiO-66: Synthesis, characterization, and comparative study

Abstract

Pharmaceutical products such as ibuprofen and naproxen pose a potencial risk to the environment and to the human health. In this context, it is necessary seek and implement new effective and low-cost technologies for water treatment such as adsorption. Metal-organic frameworks (MOFs) emerge as promising adsorbent materials due to their structural diversity and stability. The obtained MOFs were characterized by SEM/EDX, XRD, FTIR, N2 at 77 K, DLS, and PZC. According to the textural parameters, the obtained MOFs have the next surface areas: MIL-100 (Fe) 1359 m2, ZIF-8 357 m2 and UiO-66 1654 m2. Having this differences in surface areas, alongside the different PZC of each materials, affect the adsorption capacity. According to the experimental data UiO-66 and MIL-100(Fe) had the highest ibuprofen adsorption capacity (152.3 mg g-1) and naproxen adsorption capacity (278.3 mg g-1), respectively. On the other hand, ZIF-8 has the lowest adsorption capacity of ibuprofen and naproxen (85.4 and 78.9 mg g-1 respectively). It was found that the best-fitting model according to its R2 for all materials with both adsorbates was the Sips model. Moreover, all materials with all adsorbates, except for UiO-66 with naproxen, reached equilibrium within the first 120 min and fitted the pseudo-second order model. According to thermodynamic parameters and analysis of fitted kinetic models, it was determined that during adsorption, a combination of physical and chemical phenomena occurs, from which the following interactions are proposed as the main adsorption mechanisms: hydrogen bonding, π -π interactions, anion-π interactions, and Lewis’ acid/base interactions.