Synthesis of an O,N-rich porous organic polymer: efficient removal of metronidazole from aqueous solutions

Abstract

Pharmaceutical residues refer to the remnants of drugs used in the medical and food industries that have not fully decomposed. These residues pose a significant threat to human health and natural ecosystems, making them a growing global concern. Porous organic polymers (POPs) show promise as efficient adsorbents for the removal of pharmaceutical pollutants in water. In the present study, an O,N-rich porous organic polymer (ONR-POP) was synthesized via Schiff’s base condensation under solvothermal condition. The performance of the prepared ONR-POP as an adsorbent for the removal of metronidazole from aqueous solutions was evaluated. The structural properties of synthesized ONR-POP were identified by FT-IR, XRD, SEM, EDS, TGA, and BET analyses. The adsorption process of metronidazole using ONR-POP was investigated, and the highest removal efficiency of metronidazole (88%) was achieved after 30 min at 25°C and pH 4. The study of adsorption isotherms and kinetics models indicated that ONR-POP follows the Langmuir adsorption model with a high correlation coefficient of R² = 0.991 and a pseudo-second-order kinetic model. Additionally, the thermodynamic data indicate that the adsorption process is exothermic and spontaneous. These results confirm that porous organic polymers can be suitable candidates for the adsorption of pharmaceutical pollutants from water and wastewater.