Synthesis of molecularly imprinted polymer for highly selective adsorption of Sulfasalazine from contaminated...

The molecularly imprinted polymer (MIP) was synthesized using the bulk polymerization technique and characterized by Scanning electron microscope (SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller/Barrett-Joyner-Halenda (BET/BJH), Thermogravimetric Analysis (TGA), and point of zero charge (pH_PZC) analyses. The adsorption of sulfasalazine (SSZ) onto the MIP was systematically investigated under various conditions. The researchers investigated the effect of initial SSZ concentration, MIP mass, temperature, pH, and contact time. The highest removal efficiency was achieved at pH 7, MIP dosage of 0.8 g/L, and an initial SSZ concentration of 10 mg/L, with an equilibrium contact time of 75 min. The maximum adsorption capacities obtained from the Langmuir model were 217.1, 235.4, 254.3, and 284.5 mg/g at 20, 30, 40, and 50 °C, respectively, confirming a monolayer adsorption process. Kinetic analysis indicated that the adsorption followed the pseudo-second-order model (R² > 0.995), while thermodynamic studies revealed that the process was spontaneous (ΔG° = -3.41 to -8.95 kJ/mol) and endothermic (ΔH° = 38.4 kJ/mol). The MIP maintained over 93% of its initial adsorption capacity after five regeneration cycles. Competitive adsorption tests further demonstrated a significantly higher affinity of the MIP for SSZ compared with ciprofloxacin and amoxicillin. These results suggest that the synthesized MIP is a highly efficient, selective, and reusable adsorbent for removing SSZ from aqueous environments.