Publicação
Removal of Naproxen from aqueous matrices using olive stones based carbon materials as adsorbents
| Resumo: | Emerging micropollutants are substances found in the range of micrograms to nanograms per liter that are present in the various aqueous matrices of the world bringing adverse effects to the health of living beings. Naproxen, the object of study of this work, is a non-steroidal anti-inflammatory with analgesic and antipyretic properties commonly used in sore throats, muscle aching, tendinitis, synovitis, etc. The present work aims to study the removal of naproxen through adsorption using activated charcoal from the olive pit. Therefore, this work is based on developing a method of quantification of naproxen using high performance liquid chromatography, prepare 4 types of adsorbents from the olive stone by changing the activation conditions, make the physicochemical characterization of the main adsorbent (Ads 3) and study the process of removal of naproxen with HPLC from the adsorption balance isotherms with the Langmuir and Freundlich models. For the calibration straight line, concentrations of 1 to 10 ppm of naproxen were prepared and injected into the HPLC-Vis, returning a calibration line with linear characteristic with R² = 0.9976. From the 0.25 mm crushed olive stone, 4 types of adsorbents were prepared: without treatment (Ads 1), carbonized (Ads 2), chemically activated and charred (main adsorbent - Ads 3) and chemically activated and pyrolyzed (Ads 4). Adsorbent 3 has 0.52% ash content and 84% of its volume with micropores and presented good conditions to continue the analysis of the effect of temperature and pH on adsorption. The results pointed to Ads 3 as the best absorber (qm = 37.01 mg g-1 ads) with high efficiency and better cost-benefit because it did not need to undergo pyrolysis although Ads 4 had very optimistic results (qm = 23.46 mg g-1 ads), but lower than Ads 3. Ads 1 as expected was the least efficient although even without treatment it has adsorption capacity (qm = 22.46 mg g-1 ads). The temperature and pH isotherms indicate that the temperature has little significant effect, where the temperature at 35°C obtained the best results of naproxen adsorption capacity (qm = 86.24 mg g-1 ads) but not very different from 25°C (qm = 77.68 mg g-1 ads). For pH, isotherms indicate that the natural pH of the solution (4.4) is the best option for the removal of naproxen (qm = 37.01 mg g-1 ads), since the results for the pH increase were not favorable. The isotherms adjusted with the Langmuir and Freundlich models have distinct characteristics: for temperature analyses the Freundlich model had better behavior with higher R², while for pH analysis and analysis of the 4 adsorbents the Langmuir models showed better fit. The difference in the use of the models is due to optimization throughout this work, in which the time and temperature studies were the precursors, and adjustments such as the ratio of naproxen mass with adsorbent mass were optimized in the comparison studies of pHs and adsorbents. |
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| Autores principais: | Reis, Vinícius de Assis |
| Assunto: | Activated carbon Emerging micropollutants Environment High performance liquid chromatography UV-Vis Naproxen Olive stone |
| Ano: | 2022 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Instituto Politécnico de Bragança |
| Idioma: | inglês |
| Origem: | Biblioteca Digital do IPB |
| Resumo: | Emerging micropollutants are substances found in the range of micrograms to nanograms per liter that are present in the various aqueous matrices of the world bringing adverse effects to the health of living beings. Naproxen, the object of study of this work, is a non-steroidal anti-inflammatory with analgesic and antipyretic properties commonly used in sore throats, muscle aching, tendinitis, synovitis, etc. The present work aims to study the removal of naproxen through adsorption using activated charcoal from the olive pit. Therefore, this work is based on developing a method of quantification of naproxen using high performance liquid chromatography, prepare 4 types of adsorbents from the olive stone by changing the activation conditions, make the physicochemical characterization of the main adsorbent (Ads 3) and study the process of removal of naproxen with HPLC from the adsorption balance isotherms with the Langmuir and Freundlich models. For the calibration straight line, concentrations of 1 to 10 ppm of naproxen were prepared and injected into the HPLC-Vis, returning a calibration line with linear characteristic with R² = 0.9976. From the 0.25 mm crushed olive stone, 4 types of adsorbents were prepared: without treatment (Ads 1), carbonized (Ads 2), chemically activated and charred (main adsorbent - Ads 3) and chemically activated and pyrolyzed (Ads 4). Adsorbent 3 has 0.52% ash content and 84% of its volume with micropores and presented good conditions to continue the analysis of the effect of temperature and pH on adsorption. The results pointed to Ads 3 as the best absorber (qm = 37.01 mg g-1 ads) with high efficiency and better cost-benefit because it did not need to undergo pyrolysis although Ads 4 had very optimistic results (qm = 23.46 mg g-1 ads), but lower than Ads 3. Ads 1 as expected was the least efficient although even without treatment it has adsorption capacity (qm = 22.46 mg g-1 ads). The temperature and pH isotherms indicate that the temperature has little significant effect, where the temperature at 35°C obtained the best results of naproxen adsorption capacity (qm = 86.24 mg g-1 ads) but not very different from 25°C (qm = 77.68 mg g-1 ads). For pH, isotherms indicate that the natural pH of the solution (4.4) is the best option for the removal of naproxen (qm = 37.01 mg g-1 ads), since the results for the pH increase were not favorable. The isotherms adjusted with the Langmuir and Freundlich models have distinct characteristics: for temperature analyses the Freundlich model had better behavior with higher R², while for pH analysis and analysis of the 4 adsorbents the Langmuir models showed better fit. The difference in the use of the models is due to optimization throughout this work, in which the time and temperature studies were the precursors, and adjustments such as the ratio of naproxen mass with adsorbent mass were optimized in the comparison studies of pHs and adsorbents. |
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