Mestrado em Química (IQ)
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Item Sinterização, caracterização e estudo das propriedades dielétricas de cerâmicas de TiO2 co-dopadas com íons Nb5+, Al3+ e Cr3+(Universidade Federal de Goiás, 2020-05-06) Lira, Stéfane Oliveira de; Franco Júnior, Adolfo; http://lattes.cnpq.br/0187547195548392; Franco Junior, Adolfo; Gonçalves, Pablo José; Araújo, Olacir AlvesDielectric ceramics free of lead presents great interest to the scientific community due its low toxicity or absence of it. In this work, ceramic materials of aluminum, chromium and niobium doped titanium dioxide (TiO2) Ti0,995[Nb1,33(AlxCr1-x)0,66]0,005O2 with x assuming the values of 1; 0,7; 0,5; 0,3; 0,1 in mols. Such materials were obtained through solid state reaction with uniaxial and isostatic cold pressing and sintering maximum temperature of 1500 °C. Structural, optics and electrics characterization were realized via Apparent density (rap), X-Ray diffraction (XRD), Fourier transform infrared (FTIR), Ultraviolet–visible spectroscopy (UV-Vis), Raman spectroscopy and Dielectric permittivity and Impedance spectroscopy. These caracterizations indicated the formation of the tetragonal rutile phase with no spurious phases and all the samples presented 97 to 99% densification. FTIR, UV-Vis and Raman measurements confirmed the tetragonal rutile crystalline phase by means of characteristic vibrational bands, in addition to allowing the observation of the increase in defects and the reduction of the band gap with doping. The dielectric permittivity and impedance measurements prove the presence of Colossal permittivity effect (e’ ~ 106) for all the samples, increasing dielectric constant with doping. The samples high permittivity was atrtibuted to the presence of electron confinement in complex clusters of defects and the presence of potencial barriers in grain boundary.Item Síntese de carbonatos cíclicos a partir de CO2 e epóxidos catalisada por complexos metálicos com ligantes benzotiazois(Universidade Federal de Goiás, 2020-02-14) Mata, Álvaro Farias Arruda da; Chagas, Rafael Pavão das; http://lattes.cnpq.br/9712618482518275; Chagas, Rafael Pavão das; Milani, Jorge Luiz Sônego; Castro, Danielle Cangussu deCarbon dioxide is an abundant and renewable source of carbon, which can be used to replace fossil resources in the synthesis of various substances. This work aims to develop a catalytic system, using complexes with benzothiazole-derived ligands, for the synthesis of cyclic carbonates by the chemical fixation of CO2 by reaction with epoxides. The ligands 2-(2-hydroxyphenyl)-benzothiazole (L1) and 2-(2-pyridyl)-benzothiazole (L2) were used in the synthesis of eight complexes with the metals Zn(II) (7a and 8a), Co(II) (7b and 8b), Ni(II) (7c and 8c) and Mn(II) (7d and 8d). The synthesized compounds were characterized by nuclear magnetic resonance, elemental analysis, infrared and UV-vis absorption spectroscopy and thermal analysis. Initially, all complexes were active catalysts in the cycloaddition reaction between CO2 and propylene oxide for the production of the respective cyclic carbonate with high selectivity and conversions of 15% to 48%, under high pressure conditions. Under the same conditions, the control experiment converted only 2% of the epoxide. The catalytic system with complex Zn(L1)2 (8a) was the most active, so this complex was used in the optimization of the reaction by evaluating the following parameters: pressure, time, temperature, catalyst load and type of cocatalyst. The optimum condition was used in reactions with different epoxides, producing the respective cyclic carbonates with high conversion values. This is the first work to report a catalytic system that uses complexes with benzothiazole ligands for the synthesis of cyclic carbonates from CO2 and epoxides, demonstrating its efficiency in the chemical fixation of CO2.Item Os poderes das super-heroínas: possibilidade de discussão de conceitos científicos com estudantes do ensino médio(Universidade Federal de Goiás, 2020-04-22) Pinto, Pollyana de Godoy; Soares, Márlon Herbert Flora Barbosa; http://lattes.cnpq.br/9698540158266610; Soares, Márlon Herbert Flora Barbosa; Mota, Rejane Dias Pereira; Mesquita, Nyuara Araújo Da SilvaThis work highlights the process of investigation of science present in the powers of super heroines, by students of public high school in Goiás. Also emphasizing the evolution of the female presence in superhero films, which establishes the encouragement in women in more diverse spaces. The objective of this work was to verify if there was a possibility to relate the fictional powers contained in the characters with formal science. Also, to analyze the scientific level to which these students belonged. The work was carried out in a state college in the metropolitan region of Goiânia with four high school classes, the first two years, a second year and a third year. In total 122 students participated in the work. The students chose eleven super heroines, within the criteria that they themselves defined. They conducted research on the disciplines that best explained their powers, produced written works and oral presentations. The level of approximation between students' previous concepts and scientific concepts in the explanation of powers was evaluated. The results show that the strategy was satisfactory, since 58% of the concepts investigated by the students had a level of approximation with the scientific concept. The data show us that there was involvement and perspective from the students, and that this theme, guarantees motivation allowing a more pleasant science teaching to students.Item Desenvolvimento e acoplamento por deslizamento vertical de dispositivos microfluídicos colorimétricos e eletroquímicos baseados em papel usando suporte impresso em 3D para detecção multiplexada de metais(Universidade Federal de Goiás, 2020-02-17) Silva Neto, Habdias de Araujo; Coltro, Wendell Karlos Tomazelli; http://lattes.cnpq.br/8302650734477213; Coltro, Wendell Karlos Tomazelli; Paixão, Thiago Regis Longo César da; Chaves, Andréa RodriguesAs the world population increases at a rate of 80 million per year, this behavior requires an increase on demand for essential resources such as food, fuel and fiber, causing agribusiness companies to intensify the exploitation of natural resources. However, they negatively affect the environmental compartments of the region, such as fluvial systems with metal pollutants. Thus, various analytical methods have been reported to detect and quantify metals in environmental samples, such as atomic absorption spectroscopy, coupled plasma mass spectrometry and coupled plasma atomic emission spectrometry. However, these detection systems require a long training time and high financial investment, which make research on environmental pollutants in developing countries difficult. Here, we report for the first time the integration of a paper-based electrochemical and colorimetric device (ePAD and μPAD) through vertical sliding coupling on three-dimensional printed support for multiplexed detection of Zn, Cd, Pb, Fe, Ni and Cu in a water sample from the Meia Ponte River. It was possible to manufacture 90 μPADs and 140 ePADs using a chromatographic and vegetal paper, respectively. In addition, the cost price of the device was c.a. 0.03 USD (R$ 0,1), considering the paper, conductive inks, and plastic material. The combination of the electrochemical and colorimetric detection methods of the proposed analytical system did not statistically interfere with the signal of simultaneous detection of metals (significance level <95%), enabling the multiplexed detection of six metals.During the proof-of-concept, the method showed a fast analysis time (10 min), good analytical frequency (36 analyzes per hour) and detection limits were 1.46 (Zn), 1.26 (Cd) and 0.51 (Pb ) μg L-1 for electrochemical detection and 0.14 (Fe), 0.33 (Ni) and 0.15 (Cu) mg L-1 (colorimetric detection). Furthermore, the proposed method successfully demonstrated the detection of metals in Meia Ponte River water samples (range 16 to 786 μg L-1), in the recovery studies (76 to 121%) and when compared with the atomic absorption spectroscopy method (significance level of 95%). Thus, the integration of ePAD and μPAD by vertical sliding was efficient for multiplexed analysis of heavy metals and can be exploited to monitor metallic pollutants in industrial process residues, by environmental inspection agencies and in river water samples.Item O Jogo e a teoria do processamento da informação no ensino de geometria molecular(Universidade Federal de Goiás, 2020-04-28) Silva, Cleberson Souza da; Soares, Márlon Herbert Flora Barbosa; http://lattes.cnpq.br/9698540158266610; Soares, Márlon Herbert Flora Barbosa; Eichler , Marcelo Leandro; Santos , Jane Darley Alves dosThis research developed and evaluated a game based on the Theory of Information Processing, particularly, on the Computational Theory of Mind with the objective of enabling the learning of concepts related to Molecular Geometry. The Theory of Information Processing is a descriptive model that explains how the human mind processes the information it receives, thus, the Computational Theory of Mind is a type of Theory of Information Processing that lists concepts such as symbol, input, output and processing for explain the processing of information in the mental structure of individuals. In this dissertation, based on the Computational Theory of Mind, a board and card game called: GeomeQuímica, which has in its scope themes such as: Molecular Geometry, Polarities of Molecules and Angle of Bond. The main idea of this dissertation was that from the elaborated game it was possible to provide an adequate process of construction of the knowledge of concepts related to Molecular Geometry. For this, this research was characterized as a qualitative case study. It is important to highlight that in a qualitative research, the researcher does not remain distant from his object of study, on the contrary, he is within the field of analysis trying to capture the meanings of the phenomena he is studying. Thus, the author of this dissertation, and a teacher at a public school of Basic Education located in the city of Luziânia in the state of Goiás in Brazil, invited his students from two classes of the first grade of High School to participate in the aforementioned game. In one class, students participated in the game from an application perspective in which it was considered Didactic and in the other as Pedagogical. Didactic Game is that game that the teacher usually uses to reinforce content that he has already taught. On the other hand, the Pedagogical Game is one that students participate before they have even studied about the subject addressed, in order to learn from the game. While the students participated in the game, their speeches were recorded using audio and video, and later transcribed and analyzed using the Content Analysis technique. The students' speeches generated the following five categories of analysis: Doubts involving the Operation and the Rules of the Game; Evaluation; Mathematical concepts; Chemical Concepts and Associative Networks. From these categories it was possible to perceive that during the game the students presented typical characteristics of the game as pleasure, fun and little competitiveness. We infer, through the analysis of the categories, that when the students participated in GeomeQuímica acting as Didactic Game, it managed to enable a greater learning of the concepts covered. On the other hand, GeomeQuímica acting as a Pedagogical Game was able to favor learning from error, which is often not done by schools. Thus, it was possible to approximate the most relevant concepts of the Computational Theory of Mind with the concepts of Piaget's Genetic Epistemology as: symbol corresponding to scheme; assimilation input; output the accommodation and processing the equilibration.