Investigating the adsorption potential of bentonite nanoparticles as an economical adsorbent for decontamination of antibiotics from aqueous solution: kinetics and regeneration studies

This study examines the adsorption efficacy of bentonite nanoparticles for removing Trimethoprim (TMP) and Penicillin G (PNG) antibiotics from aqueous solutions, emphasizing cost-effectiveness and operational efficiency. The bentonite nanoparticles, characterized by a surface area of 210-250 m²/g and a point of zero charge (pHzpc) of ~6, demonstrated optimal performance under acidic conditions (pH 3). At an adsorbent dosage of 0.1 g/L, initial antibiotic concentration of 100 mg/L, and contact time of 90 minutes (25°C), maximum adsorption capacities of 36.07 mg/g (TMP) and 39.43 mg/g (PNG) were achieved. Adsorption kinetics adhered to a pseudo-second-order model (R² = 0.97 for TMP; R² = 0.99 for PNG), suggesting chemisorption as the rate-limiting step. Isotherm studies aligned with the Freundlich and Dubinin-Radushkevich models, indicating heterogeneous surface interactions and predominantly physical adsorption mechanisms.