Percorrer por autor "Morizaki, Gabrielle Tokawa"
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- Removal of metformin from aquatic matrices using cork-based adsorbentsPublication . Morizaki, Gabrielle Tokawa; Queiroz , Ana Maria; Ribeiro , António; Brito , Paulo; Gomes, Maria Carolina SérgiMetformin is a widely prescribed pharmaceutical for the treatment of type II diabetes. It is classified as an emerging micropollutant due to its incomplete metabolism in the human body and high prescription rates, especially for preventing chronic diseases. Consequently, it is frequently detected in aquatic environments. This study aimed to evaluate the efficiency of metformin removal from aqueous matrices through adsorption using activated carbons produced from cork waste. Adsorbents were prepared via carbonization and chemical activation using potassium hydroxide (KOH). They were characterized in terms of carbonization yield, moisture and ash content, point of zero charge (pHPZC), surface acidity/basicity, and Fourier-transform infrared spectroscopy (FTIR). Metformin quantification was performed using high-performance liquid chromatography with diode array detection (HPLC-DAD). Adsorption studies included removal efficiency, adsorption kinetics, activation energy estimation, and optimization of operational parameters. Among the parameters investigated, pH had the most significant influence, with higher removal observed under alkaline conditions for both materials. For the carbonized carbon (CC), the pseudo-second-order and Elovich kinetic models provided the best fit, suggesting a chemisorption-controlled process. In equilibrium studies, the Freundlich model best represented experimental adsorption behavior using CC adsorbent, while the Langmuir model was more appropriate when chemically activated carbon (CQ) was used, which exhibited a maximum removal efficiency of 99% at pH 11. These findings demonstrate the high adsorption performance of cork-based activated carbons, particularly those chemically activated. This highlights their potential as sustainable materials for removing metformin from aqueous systems and promoting the valorization of industrial by-products in water treatment applications.