Synthesis of a nitrogen rich covalent organic polymer for naproxen adsorption from aqueous solutions

The synthesis of a novel nitrogen-rich covalent organic polymer (NR-COP, 7) via Schiff-base condensation and its application for naproxen (NPX) removal from aqueous solutions are reported. The synthesized polymer was characterized using FT-IR, XRD, SEM, EDS, TEM, TGA, and BET analyses. The effects of pH (3–10), contact time (10–150 min), adsorbent dosage (5–15 mg), initial NPX concentration (10–100 mg/L), and temperature (25–45 °C) on adsorption performance were systematically investigated. The optimal conditions were identified as pH 6, 25 °C, a contact time of 90 min, an adsorbent dosage of 10 mg, and an initial NPX concentration of 40 mg/L. Adsorption equilibrium data were better fitted by the Langmuir model than by the Freundlich model, with an R² value of 0.9947. The adsorption kinetics followed the pseudo-second-order model, yielding a maximum adsorption capacity of 135.14 mg/g. Thermodynamic analysis indicated that NPX adsorption onto NR-COP (7) is spontaneous and exothermic. The combination of favorable adsorption capacity, thermal stability, and reusability highlights the potential of this nitrogen-rich polymer as an effective adsorbent for NPX removal from aqueous media. Its nitrogen-containing functionalities may further contribute to adsorbate–adsorbent interactions, supporting its potential application in the treatment of pharmaceutical-contaminated water. .