Programa de Pós-graduação em Engenharia Ambiental e Sanitária

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Navegando Programa de Pós-graduação em Engenharia Ambiental e Sanitária por Por Orientador "Cuba, Renata Medici Frayne"

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    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 Sérgio
    Nitrate 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.
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    Reaproveitamento de sabugo de milho para potencial remoção de formulação comercial de glifosato em fase aquosa pela técnica de adsorção
    (Universidade Federal de Goiás, 2020-03-30) Marcelino, Nayara Valéria Assis; Cuba, Renata Medici Frayne; http://lattes.cnpq.br/2178652705357657; Cuba, Renata Medici Frayne; Teran, Francisco Javier Cuba; Ostroski, Indianara Conceição
    Like the chemical industries applied to agriculture and livestock, they develop several chemicals for use in the environment, including chemicals that can be used for endocrine disrupting activities. In this context, the use of the herbicide Glyphosate (GLF), which is among the four most used agrochemicals in Brazil (glyphosate and its salts; 2,4-D; Acephate; mineral oil) is the main used, soybean and sugar cane. The main source of exposure of glyphosate to living organisms is a water intake, since water and wastewater treatment systems are not able to remove or degrade by a complete series of synthetic organic compounds. In this situation, it is necessary to use complementary treatment methods, of which adsorption may be of technical and environmental interest, due to its efficiency and, mainly, in the versatility of raw materials used for the production of material adsorbent. Thus, the objective of this study was the reuse of corn maize through the production of biochar (BC) and activated carbon (CA), for potential removal of glyphosate herbicide (GLF) (commercial use) in aqueous medium using the technique of adsorption. The BC was subjected to only the carbonization step, while the CA was subjected to carbonization followed by chemical activation with H3PO4. The adsorbents were characterized by X-ray diffraction (DRX) and infrared analysis by Fourier transform (FTIR), adsorption and N2 desorption, scanning electron microscopy (SEM) and determination of the zero charge potential (pHPCZ). The effect of the initial pH and the adsorbent mass was also evaluated. The kinetic studies of adsorption were adjusted to the models of pseudo-first and pseudo-second order. The nature of the adsorption process was studied using the Langmuir and Freundlich isotherm models, and the thermodynamic parameters calculated for the temperatures of 23, 43 and 63 ° C. The acid treatment caused an increase in the surface area (7.48 m² / g BC to 34.126 m² / g CA) favoring the formation of mesopores and had little influence on the surface loads. The adsorption of GLF proved to be highly dependent on pH and both adsorbents reached their maximum adsorption capacity at neutral pH (7.0). Both adsorbents reached equilibrium in 60 min of testing, and in just 15 min the CA reaches 93% of its maximum adsorption capacity and the BC 68%, showing a better fit to the pseudo-second model. indicating a tendency for chemical adsorption. The equilibrium data obtained experimentally, for temperatures of 23, 43 and 63 ° C, showed a better fit to the Langmuir model for the BC indicating chemisorption, and Freundlich for the CA indicating Fisissorection. Chemical activation increased the maximum adsorption capacity (Langmuir qmax) from 1.08 mg g-1 to 1.51 mg g-1 The values of the thermodynamic constants revealed that the adsorption of GLF is endothermic in nature, favored with the increase in temperature (ΔH> 0), and endergonic (ΔG> 0), indicating that the adsorption process is not spontaneous.
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    Efeito da concentração de fósforo na degradação aeróbia do glifosato em reator de leito fixo
    (Universidade Federal de Goiás, 2017-09-21) Paiva, Débora Cristina Aguiar Chaves; Cuba, Renata Medici Frayne; http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4795907Y4; Cuba, Renata Medici Frayne; Teran, Francisco Javier Cuba; Pimenta, Sandro Morais
    The present work had as objective to investigate the performance of a fixed bed aerobic reactor with biomass adhered in the treatment of waters contaminated with glyphosate and different concentrations of phosphorus. The effect of different phosphorus concentrations on the adsorption kinetics of glyphosate in a support medium was evaluated by means of the determination of the exhaust curve in a system composed of an adsorption column filled with expanded clay. The glyphosate solution used was commercial product based on Glyphosate Di-ammonium salt 445 g.L-1 (370 g.L-1 equivalent acid) and ultra purified water, with final glyphosate concentration of 8 mg.L-1. Concentrations of 0.8 mg.L-1 were used in the adsorbent assays; 8 mg.L-1; and 16 mg.L-1, and the pH values adopted were: 4; 7 and 10. The results obtained demonstrate the influence of both pH and phosphate ions on the adsorption of glyphosate in expanded clay, where the adsorption kinetics showed the influence of both parameters, in general, on higher concentrations of phosphate ions. The effect of different concentrations of phosphorus on glyphosate biodegradation kinetics was evaluated by means of temporal profiles of the glyphosate and phosphorus concentration decay in the same system used in the adsorption tests with aerobic sludge inoculation in the expanded clay. The glyphosate solution was the same as that used in the 15 mg.L-1 adsorption assays, evaluating the degradation in the presence of concentrations of 2.15 mg.L- 1; 5.37 mg.L-1; 10.75 mg.L-1; 16.12 mg.L-1; 21.5 mg.L-1; 43 mg.L-1 phosphorus. The results demonstrate the influence of phosphate ions on the degradation kinetics of glyphosate in expanded clay. It is possible to observe that glyphosate treatment efficiency increased as phosphorus concentrations increased, indicating that kinetics of degradation was directly associated to kinetics adsorptive. The data were analyzed by means of multiple regression, which was able to verify with 95% confidence the effect of the phosphorus (p <0.05) on the degradation process.