Mestrado em Engenharia Ambiental e Sanitária (EEC)
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Navegando Mestrado em Engenharia Ambiental e Sanitária (EEC) por Assunto "Adsorption"
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Item Produção de materiais adsorventes para remoção de nitrato em meio aquoso(Universidade Federal de Goiás, 2019-09-30) Araujo, Sara Sales de; Cuba, Renata Medici Frayne; http://lattes.cnpq.br/2178652705357657; Cuba, Renata Medici Frayne; Ostroski, Indianara Conceição; Scalize, Paulo SérgioNitrate contamination of surface and groundwater resources has been evident over the years, as high concentrations can cause adverse health reactions such as methemoglobinemia in newborns. In the study carried out in different Brazilian states, nitrate concentration levels above the maximum allowed for potability standards were determined, highlighted as 10mg. L-1 in the consolidation nº 5 of the Ministry of Health. In this context, there was an intensification of studies on the adsorption process using activated bichars and biosorbents, produced from agroindustrial residues to remove nitrate in aqueous medium. The use of corn cob as a precursor is favorable since the imminent generation of these residues. In this study, corncob was chemically modified with P.A. hydrochloric acid to obtain biosorbent (BS), activated biochar of oxidizing atmosphere (BCO) and activated biochar of inert atmosphere (BCI). For the prepared adsorbent materials their characteristics were determined, such as the zero charge point (pHpzc) assay which revealed for BS and BCO pHpzc 2.1, while the BCI was 6.3. In the Forrier Transform Infrared (FTIR) assay the adsorbent materials showed characteristic groups, such as carboxylic (3400 cm-1), methyl, methylene and methoxyls (2900cm-1), carbonyls (1700cm-1), aromatic rings (1600cm-1). Also, the adsorption conditions were optimized regarding the solution pH and adsorbent dosage, revealing solution pH of 2.0 for BS and BCO, and pH of 6 for BCI, and 0,75 g for BS and BCO, 1g for BCI. Adsorption isotherms and kinetics were determined, and Langmuir isotherm was better adapted for BS and Freundlich for BCO and BCI. The kinetics were pseudofirst order for BS and pseudo-second order for BCI and BCO. For the materials presented, removals were 6.16 mg.g -1 for BS, 13.33 mg.g -1 for BCO and 15.54 mg.g -1 for BCI.Item Remoção de fluoreto em carvão produzido com borra de café ativada quimicamente com lixívia de cinzas de eucalipto(Universidade Federal de Goiás, 2023-04-25) Bergamini, Mário Henrique Lobo; Oliveira, Sérgio Botelho de; http://lattes.cnpq.br/3447406257464639; Scalize, Paulo Sérgio; http://lattes.cnpq.br/0957896448117207; Scalize, Paulo Sérgio; Costa, Adilson Ben da; Albuquerque, Antonio João Carvalho deThe objective of this research was to produce a biochar from exhausted coffee grounds and chemically activate it with natural lye from eucalyptus ash to subsequently evaluate the fluoride adsorption process in an aqueous medium. The following were determined: moisture content, ash content and thermal analysis of coffee grounds; solubility, alkalinity and calcium content of eucalyptus ashes. Activated biochar was subjected to elemental composition (CHNS), X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS), N2 adsorption and desorption, pH and potential of zero charge (PZC) for characterization. To select the best production condition for activated biochar, a 3² factorial design was performed. Kinetic adsorption studies were fitted to pseudofirst order, pseudo-second order, Elovich and Weber and Moris models. The nature of the process was studied by Langmuir and Freundlich isotherm models. The result of the factorial design indicated as the best scenario the impregnation rate of 5% and the temperature of 650 °C in the carbonization. SEM showed macroporosity. XRD confirmed the amorphous characteristic of cellulosic materials. The following functional groups were identified in coffee grounds and activated biochar: alcohol or phenol, hydroxyl, methyl, methylene, carbonyl, carboxylic acid, ester, chlorogenic acid, ketone, carbonyl, amino, amide and pyranose ring. The pH of the activated biochar was equal to 8.89 and the PZC was 7.17. Preliminary adsorption tests showed that the best dosage of activated biochar was equal to 3.2 g/L and the concentration of adsorbate caused a decrease in resistance to mass transfer due to the fact that there were more active sites of activated biochar in the liquid medium. However, the removal efficiency decreased with increasing adsorbate concentration. It was observed that coffee grounds, when used as an adsorbent, promoted a small reduction in the adsorbate concentration, with an average removal efficiency of 1.35%. The adsorption kinetics revealed that equilibrium is reached around 800 min and that the pseudo-second order model fitted better. The Freundlich model fitted the experimental data with the best quality. Freundlich's constant n allowed inferring that the adsorption is favorable and the isotherm appears to be L-type, with an initial downward curvature, which suggests less availability of active sites when increasing the adsorbent concentration.