Synthesis, Characterization, and SMX Adsorption Study of a Novel Copper–Schiff Base‐Modified PVC Adsorbent

In this study, a novel polyvinyl chloride (PVC)–based adsorbent was synthesized and functionalized with a Schiff base derived from 4,4 ′ ‐diaminodiphenyl ether and vanillin, followed by complexation with copper (II) nitrate nonahydrate, to effectively remove sulfamethoxazole (SMX) from aqueous solutions. The final composite, designated as PVC‐Cu‐SbDEV, was obtained through postsynthetic coordination of the Schiff base–modified PVC with Cu(II) ions. The structural and surface characteristics of the adsorbent were thoroughly characterized using FTIR, SEM, EDX, BET, and TGA analyses. Parametric studies including solution pH, contact time, initial SMX concentration, and temperature were conducted to determine optimal adsorption conditions. Under the optimized conditions—pH 6, contact time of 120 min, initial SMX concentration of 80 mg L −1 , and temperature of 30°C—the adsorbent exhibited a maximum adsorption capacity of 165 mg g −1 and a removal efficiency of 68%. Isothermal and kinetic analyses indicated that the adsorption process followed the Freundlich isotherm model and pseudo‐second‐order kinetics, suggesting a heterogeneous adsorption surface and chemisorption as the dominant mechanism. Thermodynamic evaluations further revealed that the process was endothermic and spontaneous, with values of Δ H ° = +29.5 kJ mol −1 , Δ G ° ranging from −1.2 to −3.1 kJ mol −1 , and Δ S ° = 0.105 kJ mol −1 K −1 . Overall, the PVC‐Cu‐SbDEV adsorbent demonstrated significant efficiency for SMX removal, showing a substantial improvement in performance compared to unmodified PVC.