Programa de Pós-graduação em Química

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Navegando Programa de Pós-graduação em Química por Por Orientador "Alonso, Christian Gonçalves"

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    Tecnologia supercrítica aplicada ao tratamento de águas contaminadas por fármacos
    (Universidade Federal de Goiás, 2022-04-29) Dias, Isabela Milhomem; Alonso, Christian Gonçalves; http://lattes.cnpq.br/7285754665946583; Alonso, Christian Gonçalves; Silva, Fábio Moreira da; Freitas, Fernanda Ferreira; Sgobbi, Lívia Flório; Coltro, Wendell Karlos Tomazelli
    The growth of the world population has led to the increased disposal of pharmaceutical products in the environment. Also, a wide variety of drugs used for the prevention and treatment of diseases have a low metabolic rate in humans and are often released into the environment in their unaltered form. These contaminants may offer potential risks to human health and the ecosystem. As a consequence, water is one of the most affected parts, because it is involved in various human activities. Currently, there are several processes used in water treatment, which use physical, chemical, and biological methods to remove pollutants from wastewater. However, methods of wastewater treatment have not demonstrated efficiency for the complete degradation of these compounds, or they are often impractical to treat a large volume of residues. With regard to the need to effectively treat these pollutants, this study presents the investigation of the supercritical water oxidation (SCWO) process applied in the treatment of aqueous residues contaminated with pharmaceuticals using a continuous flow reactor. For this purpose, it was investigated the degradation of amoxicillin in industrial pharmaceutical effluent, antibiotics, anxiolytics/antidepressants, and antihypertensive/cardiovascular drugs in an aqueous solution. Reaction tests were separated by therapeutic classes. In that way, a total of 20 drugs were evaluated. For all four scenarios related to each pharmaceutical class, the conditions of temperature, flow rate, and H2O2 concentration were optimized to maximize the total organic carbono removal rate (%RCOT). In the degradation of industrial effluent contaminated with amoxicillin, both temperature and flow parameters had the greatest effect on the %RCOT of the liquid phase, whose maximum value reached was 60.1%. In the gaseous product, the formation of H2, CO2, and CH4 stood out with a total volumetric flow of 6.45 mL/min. In the degradation of 6 antibiotics in an aqueous solution, the temperature was the most significant effect to achieve a %RCOT of 64.1%. The gaseous product, mostly H2 and CO2, had a total volumetric flow rate of 18 mL/min, a value almost 3 times greater than the feed flow rate. During the degradation of 5 anxiolytic/antidepressant contaminants, both parameters of temperature and H2O2 concentration had the greatest impact on %RCOT (85.9%). The total gas flow rate was 11 mL/min and, once again, among the 6 gases determined in the gaseous product, H2 and CO2 were more relevant. In the treatment of cardiovascular/antihypertensive drugs, the maximum %RCOT achieved was 92.1%, and both temperature and H2O2 concentration parameters had the greatest influence on this response. CO2 (98%) was the major constituent of the gas composition that had a total volumetric flow of 26.3 mL/min, which corresponds to twice the feed flow rate used. Briefly, for most of the four scenarios studied, the optimized conditions of temperature, flow rate, and H2O2 concentration were approximately 692°C, 6.6 mL/min, and 292% (m/m), respectively. With an exception in the cardiovascular/antihypertensive degradation condition that occurred at a lower temperature (601°C), intermediate flow rate (13.3 mL/min), and low H2O2 concentration (65%; m/m). Furthermore, for all cases evaluated, most of the limits recommended by national and international legislation regulating water quality were met. In the toxicity essays, exposure to the microcrustaceans Artemia salina revealed toxicity for some treated samples. The lethal concentration, in %(v/v), to kill 50% of the population (LC50) were approximately 12%, 555%, 32%, and 4% for industrial effluent with amoxicillin, and for all aqueous solution with antibiotics drugs, anxiolytic/antidepressant drugs, and cardiovascular/antihypertensive drugs, respectively. Given that, the SCWO technology applied to the treatment of wastewater contaminated with drugs revealed simultaneously, high oxidative power of organic matter and production of valuable energy gases, such as H2, methane, and synthesis gas. The toxicity of some molecules produced is a challenging issue to be addressed. However, due to the high oxidative power, volume and speed of waste processing, the positive contributions of SCWO in the treatment of aqueous waste are undeniable.
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    Catalisadores Cu/Al2O3 promovidos com Co e Zn aplicados à gaseificação de etanol em meio contendo água em condições supercríticas
    (Universidade Federal de Goiás, 2018-07-19) Mourão, Lucas Clementino; Oliveira, Guilherme Roberto de; http://lattes.cnpq.br/8239498431579015; Alonso, Christian Gonçalves; http://lattes.cnpq.br/7285754665946583; Oliveira, Sérgio Botelho de; Colmati Júnior, Flávio
    The great environmental concern, coupled with the risk of depletion of non-renewable raw material, has driven the search for new sustainable technologies with major concern to the reduction of pollutant emissions. Hydrogen, a chemical of enormous importance to industrial plants, stands out as a clean and renewable energy source. This chemical is commonly produced from non-renewable sources, such as natural gas reforming. Due to specific reaction conditions, the supercritical water gasification of wet biomass is a promising way for the production of hydrogen and others high added value fuel gases. Ethanol is an attractive material because it is renewable, has low toxicity compared to other resources and has high hydrogen content in its molecule. In order to become this technology viable, a decisive point is the development of a catalyst aiming at cost reductions and high selectivity to the products of interest. In this work, ethanol gasification was carried out in supercritical water with heterogeneous catalysts. The tests were performed on an Inconel Alloy 625 tubular reactor under the following operating conditions: temperatures of 400, 450, 500, 550, 600 and 650 ºC, pressure of 250 bar, 5 g loading of heterogeneous catalyst, reactor feed: ethanol/water molar ratio of 1:10 and mass flow rate of 5 g/min. The catalysts were synthesized by wet impregnation method using aqueous solutions of Cu, Co and Zn nitrates as precursors for the active phase and spherical pellets of Al 2 O 3 as catalytic support. The catalysts and the catalytic support were characterized by Thermogravimetry and Differential Thermal Analysis (TG/DTA), X-Ray Fluorescence (XRF), Scanning Electron Microscopy (SEM), textural analysis by Adsorption/Desorption Isotherms of N 2 at 77 K and X-Ray Diffraction (XRD). The gasification results indicated that H 2 production was mainly due to ethanol dehydrogenation. The catalysts showed higher conversions than observed for catalytic support only. The CuAl catalyst showed higher H 2 selectivity as well as higher H 2 molar flow at 650 °C. The CoZnAl catalyst showed a high tendency for C 2 H 4 formation at any reaction temperature, especially at 650 °C.
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    Gaseificação catalítica de efluente da indústria de biodiesel para a produção de hidrogênio
    (Universidade Federal de Goiás, 2023-04-28) Mourão, Lucas Clementino; Alonso, Christian Gonçalves; http://lattes.cnpq.br/7285754665946583; Alonso, Christian Gonçalves; Corazza, Marcos Lúcio; Chagas, Rafael Pavão das; Colmati Júnior, Flávio; Alves, Helton José
    The increasing global pollution, combined with a growing demand for energy, is driving the search for environmentally-friendly alternatives in energy production. Hydrogen, which has emerged as an important energy vector, is primarily produced from non-renewable sources such as petroleum. The development of innovative technologies has facilitated the utilization of renewable sources for hydrogen production, such as Supercritical Water Gasification (ScWG) of biomass. Among the potential feedstocks for hydrogen production, glycerol, a byproduct of the biodiesel industry, stands out as a promising candidate for ScWG. Due to the increasing production of biodiesel, a large supply of glycerol is being produced without a corresponding increase in demand. As a result, the biodiesel production chain has garnered increased interest from several research initiatives aimed at valorizing waste materials into higher value-added products. Combined with heterogeneous catalysis, the ScWG process can increase selectivity towards products of interest and achieve high conversion efficiency of organic matter, even with short residence times. In this work, the catalytic gasification of glycerol and real wastewater from a biodiesel industry were evaluated. Ni based catalyst were synthetized by simple and fast wet impregnation method of metallic nitrates supported on a honeycomb cordierite (CRD) structure. The catalysts were characterized by SEM-EDS, XRD, N2 adsorption/desorption, XRF, WDS and TGA. The performance of the Ni-based catalyst was evaluated in the ScWG of glycerol and compared to two commercial Automotive Catalysts (ACs). The ScWG of glycerol was carried out under different conditions in order to establish optimal operating parameters. The tests were conducted at reactor temperatures ranging from 400ºC to 700ºC, a system pressure of 25 MPa, and glycerol mass concentrations ranging from 10% to 34%. For optimal conditions (600 ºC and glycerol 10wt%), the results indicated that Ni/CRD catalyst showed the highest H2 yield (1,40 mol/mol C) and carbon conversion (95%). Although they have shown efficiency in the gasification of glycerol, the ACs showed higher tendencies for activity loss in carbon conversion compared to Ni based catalys over time (300 min). Preliminary tests using real industrial effluent (BIOD) were conducted, evaluating parameters of temperature (400 - 600°C), feed flow rate (10 - 20 mL/min), and effluent concentration based on total organic carbon (TOC) (50 - 100%). The results showed that temperature had the greatest influence on gasification, with a carbon conversion of 77% and an H2 yield of 2.85 mol/mol C at 600°C (10 mL/min; 50% TOC). Catalytic test conducted under the best condition (600 ºC; 10 mL/min; 100% TOC) showed higher carbon conversion, while non-catalytic test obtained higher H2 selectivity (76%). The results showed that structured catalyst has great potential to enhance the production of H2-rich gas specially from glycerol GASc. The use of biodiesel residue as a raw material for the ScWG process is promising since it allows the treatment of the residue and the production of H2-rich gas simultaneously.
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    Aplicação da tecnologia supercrítica no tratamento de resíduos plásticos presentes em amostras de água
    (Universidade Federal de Goiás, 2023-12-21) Viana , Júlio Cezar Vieira; Alonso, Christian Gonçalves; http://lattes.cnpq.br/7285754665946583; Alonso, Christian Gonçalves; Montel, Adão Lincon Bezerra; Silva, Donizete Xavier da; Oliveira, Heibbe Cristhian Benedito de; Brito, Nubia Natalia de
    Phthalic acid esters (PAEs) and bisphenol A (BPA) are plastic waste classified as emerging organic contaminants that can harm biota and human health. These residues arise as a result of the fragmentation of plastics into their monomers or the leaching of compounds used as plasticizers, such as BPA and DEP. In addition to contaminants of emerging concern, these compounds are also classified as endocrine disruptors (EDCs), interacting with estrogen receptors and causing harm to human health and the environment. Even with the availability of physical and chemical wastewater treatment methods, classical treatment methods for these compounds have proven not to be efficient in removing these refractory compounds. Therefore, the objective of this work was to use supercritical water oxidation (OASC) technology to investigate the degradation of BPA and DEP plastic waste in aqueous samples. The variables flow rate, temperature, concentration of oxidizing agent (H2O2) and homogeneous and heterogeneous catalyst, such as Cu(NO3)2 and metallic copper wire, respectively were used as parameters for the tests. Metallic copper was also used in the form of a wire together with H2O2. After treatment using OASC Total organic carbon (TOC) removal efficiencies were found to increase linearly with increasing temperature in the range of 400°C to 700°C for all tests with BPA and DEP. For all tests carried out, the best efficiency in removing total organic carbon (TOC) for BPA was achieved at a temperature of 700°C, oxidant concentration of 60 mM and flow rate of 10 mL.min-1 , reaching 91% of removal. For DEP, the best removal efficiency was achieved at a temperature of 700°C, oxidant concentration of 23 mM and flow rate of 10 mL.min-1, achieving 85% removal. Gas chromatography analysis was carried out for the gaseous components and revealed the presence of hydrogen, carbon dioxide, ethane, ethylene, methane and carbon monoxide gases. The analysis of the liquid fraction for BPA samples in the best treatment condition was carried out using liquid chromatography coupled to mass spectrometry and revealed the presence of the intermediate 2-phenyl2-propanol as the main degradation product. The liquid fraction for DEP samples in the best treatment condition was performed by gas chromatography coupled to mass spectrometry and revealed the presence of aliphatic chain hydrocarbons, such as decosane, triacontane, tetracosane and eicosane as the main degradation products. Therefore, the use of supercritical technology proved to be an efficient method for treating aqueous samples containing BPA and DEP.