Investigação dos mecanismos de falha na remoção de ibuprofeno por zeólitas modificadas

Abstract

The increasing presence of pharmaceutical residues in aquatic environments, especially anti-inflammatory drugs such as ibuprofen, has become a significant environmental concern due to their persistence and low removal rates in conventional water and wastewater treatment plants. Among the investigated solutions, advanced oxidation processes combined with heterogeneous catalysis have emerged as promising alternatives, particularly when zeolites are employed as catalytic supports. Surface adsorption on zeolites is another method used for treating pharmaceutical-contaminated water, enabled by their high surface area and porous structure, which promote physical and/or chemical interactions with adsorbed molecules. In this study, the degradation and adsorption capacity of ibuprofen in aqueous medium was evaluated using zeolite (13X and 3A)/MnFe₂O₄ composites (System 1) and zeolite (13X and 3A)/FeSO₄·7H₂O composites (System 2) activated by peroxydisulfate (PDS), in addition to adsorption tests using pre-treated zeolites. System 1 was prepared through ultrasonic pre-treatment of zeolites followed by hydrothermal impregnation of MnFe₂O₄. System 2 employed constant agitation in hydrochloric acid, followed by impregnation in diluted ferrous sulfate solution. For surfactant-modified zeolites, the materials were washed with deionized water and functionalized with cetyltrimethylammonium bromide (CTAB) for adsorption purposes. Ibuprofen quantification was performed by UV-Vis spectrophotometry using calibration curves. Degradation assays were conducted in a glass reactor with zeolite, catalyst, and PDS, while adsorption tests used the modified zeolites, all under an initial ibuprofen concentration of approximately 50 mg/L. The results showed that the impregnation methods were largely ineffective due to visible degradation of the zeolite support, spectrophotometric interferences, and low degradative performance, except for sample Z-Fe₂-H. Adsorption processes also exhibited lower-than-expected capacities under similar conditions. It is concluded that the zeolites used in both processes have low porosity and mechanical resistance, making them unsuitable as supports for aggressive or invasive impregnation methods.