Efficient Removal of Ibuprofen and Diclofenac Sodium Using Modified Bentonites: Adsorption Studies and Performance in Real Water

This study investigates the adsorption of ibuprofen (IBU) and diclofenac sodium (DS) using bentonite modified with varying amounts (50, 75, and 100% of cation exchange capacity—CEC) of two surfactants: octadecyl(dimethylbenzyl)ammonium (ODMBA) chloride and hexadecyltrimethylammonium (HDTMA) bromide. The resulting organobentonites were characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry/thermogravimetric analysis (DSC/TG), and zeta potential analysis. The results indicated that higher surfactant concentrations in organobentonites improved adsorption efficiencies for both drugs, while ODMBA-modified organobentonites exhibited notably larger adsorption capacities than HDTMA-modified samples. The adsorption isotherms fitted well to both the Langmuir and Freundlich models, with a better fit observed for the Freundlich model. The highest adsorption capacities were 102 mg/g for IBU and 160 mg/g for DS on sample OB-100 (organobentonite with 100% of ODMBA). Characterization of samples after drug adsorption, using FTIR, zeta potential and DSC/TG analysis, confirmed drug presence in organobentonites. Adsorption tests of DS in real river water (Danube and Sava rivers) showed that OB-100 demonstrated high removal capacity for DS. The findings suggest that organobentonites are low-cost adsorbents with potential for the removal of pharmaceutical contaminants from real aquatic environments.