Zeotype porous coordination networks as potential adsorbents for removing nonsteroidal anti-inflammatory drugs from water

Nonsteroidal anti-inflammatory drugs (NSAIDs) are emerging organic pollutants in aquatic systems. Although their removal is essential, it remains challenging. In the present study, mesoporous PCN-777(Zr), PCN-333(Cr), and PCN-333(Fe) were constructed and then applied for exploring their adsorption performances for indomethacin sodium (IDM), diclofenac sodium (DCF), and ketoprofen (KTF). In comparison to PCN-333(Fe), PCN-777(Zr) and PCN-333(Cr) exhibited much higher adsorption capacities of IDM, DCF, and KTF, thus they were selected as adsorbents for the subsequent investigations. Then we evaluated their adsorption kinetic and isotherm features, which could be well described by pseudo-second-order kinetic and Langmuir isotherm models. Especially for IDM molecules, PCN-777(Zr) and PCN-333(Cr) displayed adsorption capacities of 793.6 and 806.5 mg·g^–1, ranking first among various previously reported adsorbents. Furthermore, the thermodynamics parameters confirmed the endothermic and spontaneous adsorption processes. Effects of pH on the adsorbent surface charges and the NSAIDs adsorption capacities were examined in order to uncover the possible mechanisms behind the present adsorption process. The synergy effects of electrostatic interactions, H-bond interactions, and π-π stackings may contribute to the decontamination of IDM, DCF, and KTF. The coexisting salt ions and organic impurities were insensitive to IDM, DCF, and KTF removal. Both adsorbents also exhibited satisfactory reproducibilities after five consecutive adsorption-desorption cycles. The adsorbents reported herein could be exploited as a promising protocol for the treatment of NSAIDs-contaminated effluents.