Amina Ferah, Fatiha Benmahdi, Kamel-Eddine Bouhidel, Imene Abdou, Hafidha Ferroudj
Sulfamethazine (SMZ) has become a widespread pollutant in aquatic environments, posing serious ecological risks and contributing to the development of antimicrobial resistance. Conventional water treatment techniques are generally inefficient at eliminating such pharmaceuticals; however, adsorption using polymeric resins offers a promising alternative. This study investigates the removal of SMZ using a strong acid cation-exchange resin (Purolite C100E). Batch experiments were conducted to examine the influence of key operational parameters, including pH, contact time, resin dosage, temperature, stirring speed, exchangeable cation form, and the presence of a co-adsorbate. Equilibrium isotherm experiments were performed using initial SMZ concentrations in the range of 20–280 mg/L. Operating conditions (pH 5, resin dosage 1 g/L, and contact time 150 min) were selected to achieve high removal efficiency, while the intrinsic adsorption performance of the resin was evaluated using equilibrium isotherms. The adsorption data were best described by the Langmuir model, yielding a high maximum adsorption capacity (qm) of 338.92 ± 21.46 mg/g, which is superior to many previously reported adsorbents. Kinetic studies showed good agreement with the pseudo-second-order model, and thermodynamic analysis confirmed that the adsorption process is spontaneous and exothermic. FTIR analysis indicated that SMZ adsorption is mainly governed by hydrogen bonding and π–π interactions rather than electrostatic attraction. The resin exhibited good reusability over three adsorption–desorption cycles, and competitive adsorption tests demonstrated high selectivity toward SMZ. These results indicate that Purolite C100E is an efficient, selective, and reusable adsorbent for the removal of sulfonamide antibiotics from contaminated water.