Percorrer por autor "Morizaki, Gabrielle Tokawa"
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- Remoção de metformina de matrizes aquosas por meio de adsorventes à base de cortiçaPublication . Morizaki, Gabrielle Tokawa; Gomes, Maria Carolina Sérgi; Queiroz, Ana; Brito, Paulo; Ribeiro, António E.As atividades antrópicas associadas ao desenvolvimento industrial desenfreado, à urbanização e ao crescimento populacional exponencial resultaram na presença alarmante de diversas substâncias, consideradas poluentes, em corpos hídricos. Tornou-se crucial implementar medidas de controlo e monitoramento desses compostos para mitigar os impactos ambientais e preservar a qualidade dos recursos hídricos para as futuras gerações. Entre as substâncias preocupantes estão os micropoluentes emergentes, um grupo de contaminantes que inclui produtos de higiene, fármacos, hormônios e pesticidas. A deteção e quantificação desses micropoluentes exigem técnicas analíticas avançadas, já que são encontrados em concentrações muito baixas (μg/L a ng/L). Apesar disso, esses poluentes representam riscos consideráveis ao meio ambiente e à saúde humana, em especial os fármacos, já que são parcialmente metabolizados pelo corpo humano, e o restante é excretado nos sistemas aquáticos. A metformina, amplamente prescrita para o tratamento da diabetes tipo 2, é um exemplo de fármaco encontrado cada vez mais nos ambientes aquáticos devido ao seu metabolismo incompleto e seu uso generalizado. Relata-se que a metformina pode estimular a expressão de genes ligados às vias hormonais endócrinas, e seus subprodutos clorados na água potável têm efeitos tóxicos no ambiente aquático. Diversos métodos de tratamento têm sido explorados na remoção de fármacos em águas residuais, com a adsorção se destacando como uma técnica eficaz. O carvão ativado, especialmente derivado de biomassa renovável, por exemplo a cortiça, tem atraído atenção devido à sua eficiência e baixo custo na remoção de poluentes orgânicos da água residual, apresentado uma estrutura com alta área superficial e porosa. Essa abordagem não só oferece uma solução sustentável, como também se alinha aos princípios da economia circular pela utilização de materiais orgânicos descartados.
- 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.
- Removal of metformin from aquatic matrices using cork-based adsorbentsPublication . Morizaki, Gabrielle Tokawa; Gomes, Maria Carolina Sérgi; Queiroz, Ana; Brito, Paulo; Ribeiro, António E.Anthropogenic activities associated with industrial development, urbanization, and population growth have significantly contributed to the presence of various pollutants in aquatic environments. Among these contaminants, emerging micropollutants have raised considerable concern. The detection and quantification of these substances require advanced analytical techniques due to their occurrence at extremely low concentrations (μg/L to ng/L). These pollutants pose substantial environmental and human health risks, particularly pharmaceuticals. Metformin, a pharmaceutical prescribed for the treatment of type 2 diabetes, is increasingly detected in aquatic environments due to its incomplete metabolism and widespread prescription. Some studies indicate that metformin can stimulate the expression of genes associated with endocrine hormone pathways, while its chlorinated byproducts in drinking water exhibit toxic effects on aquatic ecosystems. Several treatment strategies have been investigated for removing pharmaceuticals from wastewater, with adsorption emerging as a practical approach. Activated carbons, particularly those derived from renewable biomass such as cork, have gained attention due to their high efficiency and cost-effectiveness in the removal of organic pollutants from wastewater. The present study investigates the efficiency of metformin removal from aqueous matrices using cork- based adsorbent materials. The proposed methodology encompasses the production of adsorbents via physical and chemical activation. The physical activation involved the carbonization of cork at 550°C for 1 hour. In contrast, the chemical activation comprised a pre-carbonization step at 550°C for 1 hour and impregnation with KOH at a 1:5 ratio (biochar: KOH). The impregnated material was then carbonized at 750°C for 1 hour. The characterization of the adsorbents includes calculation of carbonization yield, determination of the point of zero charge (pHpzc), analysis of acidic and basic surface sites, FTIR, TGA and BET. Kinetic and equilibrium adsorption studies will be carried out later. For this purpose, a metformin quantification method using HPLC was developed.
- Removal of metformin from aquatic matrices using cork-based adsorbentsPublication . Morizaki, Gabrielle Tokawa; Gomes, Maria Carolina Sérgi; Queiroz, Ana; Brito, Paulo; Ribeiro, António E.Metformin is considered an emerging micropollutant, belonging to the pharmaceutical class, and is widely used in the treatment of type 2 diabetes. Due to its incomplete metabolism and extensive prescription for chronic disease management, it has been frequently detected in aquatic environments. Even at trace concentrations, it may cause endocrine disruptions in aquatic biota and lead to the formation of toxic byproducts during water treatment.1,2 In this context, the present study aimed to evaluate the efficiency of metformin removal from aqueous matrices through the adsorption process, using activated carbons produced from cork residues. The methodology involved the preparation of the adsorbents via physical activation (CF) and chemical activation using potassium hydroxide (KOH) (CQ), followed by characterization in terms of carbonization yield, moisture and ash content, point of zero charge (pHPZC), presence of acidic and basic surface functional groups, and Fourier-transform infrared spectroscopy (FTIR). Metformin quantification was carried out by high-performance liquid chromatography with diode array detection (HPLC-DAD). Studies on drug removal, adsorption kinetics, activation energy estimation, and evaluation of operational parameters influencing the process, such as adsorbent dosage, pH, and initial metformin concentration, were conducted. The results demonstrated that the type of activation applied to each carbon significantly influenced the physicochemical properties of the materials, as well as their adsorption performance. According to the kinetic studies, adsorption equilibrium was reached within the first minutes for CQ, while for CF it was more gradual. In equilibrium studies, the Freundlich and Langmuir isotherm models were applied. For CF, both models showed a good fit, with a predominance of the Freundlich model, indicating a slightly heterogeneous surface and favorable adsorption. For CQ, the Langmuir model provided a better fit, with a high maximum adsorption capacity, suggesting monolayer adsorption on a more homogeneous surface.3,4 From the study carried out, the activated carbons produced from cork residues demonstrated high performance as promising materials for the removal of metformin in aqueous media, particularly those obtained through chemical activation, achieving a removal efficiency of approximately 99.0% under optimized alkaline pH conditions (pH 11). The use of this residue as a raw material highlights the potential of renewable-origin adsorbents in water treatment processes, contributing to the valorization of an abundant by-product in Portugal and to the development of more environmentally sustainable solutions, in line with the principles of a circular economy.