Pub Date : 2023-10-09DOI: 10.21577/0100-4042.20230051
Paulo R. de Oliveira, R. Rittner, Palimécio Guerrero Jr., P. Batista, G. Costa
Textbooks show that in cis-1,3-disubstituted cyclohexane molecule, the conformer with the substituents in the diaxial positions is higher in energy and hence, it presents a low population in the conformational equilibrium. The diaxial conformer is destabilized by the repulsion between the substituent groups and the axial hydrogen atoms on the same side of the ring. This interaction is known as the 1,3-diaxial interaction. In this study, the solvent effect on the conformational equilibria of cis-3-N-ethylaminocyclohexanol (cis-3-EACOL) and cis-3-N,N-diethylaminocyclohexanol (cis-3-DEACOL) has been assessed through the spin-spin coupling constant (3JHH). The results show that the diaxial conformation of cis-3-EACOL decreases from 92% in CCl4 (∆Gee-aa = 1.48 kcal mol-1 ) to 10% in DMSO-d6 (∆Gee-aa = −1.31 kcal mol-1). For cis-3-DEACOL the diaxial conformer decreased from 36% in CCl4 (∆Gee-aa = −0.33 kcal mol-1) to 7% in Pyridine-d5 (∆Gee-aa = −1.55 kcal mol-1). The stabilization of the diaxial conformer in nonpolar solvents takes place due to the O-H···N intramolecular hydrogen bond, which overcomes the 1,3-diaxial steric interactions.
{"title":"APPLICATIONS OF NMR AND THEORETICAL CALCULATIONS TO STUDY THE O-H∙∙∙N INTRAMOLECULAR HYDROGEN BOND EFFECT ON THE CONFORMATIONAL EQUILIBRIUM OF CIS-3-N-ETHYLAMINOCYCLOHEXANOL AND CIS-3-N,N-DIETHYLAMINOCYCLOHEXANOL","authors":"Paulo R. de Oliveira, R. Rittner, Palimécio Guerrero Jr., P. Batista, G. Costa","doi":"10.21577/0100-4042.20230051","DOIUrl":"https://doi.org/10.21577/0100-4042.20230051","url":null,"abstract":"Textbooks show that in cis-1,3-disubstituted cyclohexane molecule, the conformer with the substituents in the diaxial positions is higher in energy and hence, it presents a low population in the conformational equilibrium. The diaxial conformer is destabilized by the repulsion between the substituent groups and the axial hydrogen atoms on the same side of the ring. This interaction is known as the 1,3-diaxial interaction. In this study, the solvent effect on the conformational equilibria of cis-3-N-ethylaminocyclohexanol (cis-3-EACOL) and cis-3-N,N-diethylaminocyclohexanol (cis-3-DEACOL) has been assessed through the spin-spin coupling constant (3JHH). The results show that the diaxial conformation of cis-3-EACOL decreases from 92% in CCl4 (∆Gee-aa = 1.48 kcal mol-1 ) to 10% in DMSO-d6 (∆Gee-aa = −1.31 kcal mol-1). For cis-3-DEACOL the diaxial conformer decreased from 36% in CCl4 (∆Gee-aa = −0.33 kcal mol-1) to 7% in Pyridine-d5 (∆Gee-aa = −1.55 kcal mol-1). The stabilization of the diaxial conformer in nonpolar solvents takes place due to the O-H···N intramolecular hydrogen bond, which overcomes the 1,3-diaxial steric interactions.","PeriodicalId":49641,"journal":{"name":"Quimica Nova","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68272059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-09DOI: 10.21577/0100-4042.20230050
C. Bertol, Gabriel Felimberti, Karini da Rosa, E. Rizzon, R. Pereira, L. Kreutz, Pedro Froelich
Alogliptin (ALG) benzoate is an oral hypoglycemic drug that works as a DPP-4 inhibitor to prevent incretin degradation. Forced stability studies use high temperatures to decompose drugs and estimate their behavior at low temperatures. We aimed to evaluate the thermal stability of ALG using two techniques: isothermal thermogravimetry (TGA) and degradation in an oven followed by liquid chromatography (LC-PDA) analysis. ALG was subjected to 150, 155, 160, 165, and 170 °C up to 10% of mass loss in isothermal TGA. In the oven, the drug was submitted to 130, 140, 150, 155, 160, and 170 °C. Kinetic parameters were calculated with the Arrhenius model. ALG followed zero-order kinetics, in which the degradation rate did not depend on reagent concentration. Activation energy ranged from 31.0 to 35.9 kcal mol-1. The degraded drug was less toxic in a cytotoxicity assay in CRIB cells than the undegraded drug. The TGA method is faster and more practical than the oven followed by LC-PDA, and the data present a correlation. Here we described the kinetic parameters of ALG degradation, improving the knowledge about the drug and assisting in developing new formulations from the drug.
{"title":"PREDICTION OF ANTI-DIABETIC ALOGLIPTIN STABILITY BY ISOTHERMAL STUDIES","authors":"C. Bertol, Gabriel Felimberti, Karini da Rosa, E. Rizzon, R. Pereira, L. Kreutz, Pedro Froelich","doi":"10.21577/0100-4042.20230050","DOIUrl":"https://doi.org/10.21577/0100-4042.20230050","url":null,"abstract":"Alogliptin (ALG) benzoate is an oral hypoglycemic drug that works as a DPP-4 inhibitor to prevent incretin degradation. Forced stability studies use high temperatures to decompose drugs and estimate their behavior at low temperatures. We aimed to evaluate the thermal stability of ALG using two techniques: isothermal thermogravimetry (TGA) and degradation in an oven followed by liquid chromatography (LC-PDA) analysis. ALG was subjected to 150, 155, 160, 165, and 170 °C up to 10% of mass loss in isothermal TGA. In the oven, the drug was submitted to 130, 140, 150, 155, 160, and 170 °C. Kinetic parameters were calculated with the Arrhenius model. ALG followed zero-order kinetics, in which the degradation rate did not depend on reagent concentration. Activation energy ranged from 31.0 to 35.9 kcal mol-1. The degraded drug was less toxic in a cytotoxicity assay in CRIB cells than the undegraded drug. The TGA method is faster and more practical than the oven followed by LC-PDA, and the data present a correlation. Here we described the kinetic parameters of ALG degradation, improving the knowledge about the drug and assisting in developing new formulations from the drug.","PeriodicalId":49641,"journal":{"name":"Quimica Nova","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68271935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-09DOI: 10.21577/0100-4042.20230046
Samuel Santos, Cassiane Dutra, Luiz Fontoura
Alcohol residues in biodiesel can be present even after the purification steps. It diminishes the flash point, lubricity and cetane number. The standard technique to quantify residual alcohol in biodiesel is the FID-GC with headspace sampling. NMR, although underused for quantitative analyses, requires no special sample preparation, and consumes low volume of solvent. In this work, methodologies for the residual methanol and ethanol contents in soy biodiesel by 1H-NMR in a 9.4 T (400 MHz) spectrometer by standard addition were developed and validated. Quantification limits were found equal to 0.07 and 0.08% respectively, so more than twice lower than the maximum level acceptable, which is 0.2%. Accuracy and precision were considered suitable for the alcohol content around the specification limit.
生物柴油中的酒精残留物即使经过提纯步骤也可能存在。它降低了闪点、润滑性和十六烷值。定量生物柴油中残醇的标准技术是顶空取样FID-GC。核磁共振虽然在定量分析中使用不足，但不需要特殊的样品制备，并且消耗的溶剂量小。本研究建立并验证了在9.4 T (400 MHz)谱仪中标准添加1H-NMR测定大豆生物柴油中残留甲醇和乙醇含量的方法。定量限分别为0.07%和0.08%，比可接受的最大限量0.2%低2倍以上。准确度和精密度被认为适合于酒精含量在规范限度附近。
{"title":"DETERMINATION OF RESIDUAL METHANOL AND ETHANOL IN BIODIESEL BY 1H-NMR","authors":"Samuel Santos, Cassiane Dutra, Luiz Fontoura","doi":"10.21577/0100-4042.20230046","DOIUrl":"https://doi.org/10.21577/0100-4042.20230046","url":null,"abstract":"Alcohol residues in biodiesel can be present even after the purification steps. It diminishes the flash point, lubricity and cetane number. The standard technique to quantify residual alcohol in biodiesel is the FID-GC with headspace sampling. NMR, although underused for quantitative analyses, requires no special sample preparation, and consumes low volume of solvent. In this work, methodologies for the residual methanol and ethanol contents in soy biodiesel by 1H-NMR in a 9.4 T (400 MHz) spectrometer by standard addition were developed and validated. Quantification limits were found equal to 0.07 and 0.08% respectively, so more than twice lower than the maximum level acceptable, which is 0.2%. Accuracy and precision were considered suitable for the alcohol content around the specification limit.","PeriodicalId":49641,"journal":{"name":"Quimica Nova","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68272080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-09DOI: 10.21577/0100-4042.20230053
D. Borsato, M. Clemente, Heloisa Silva, Nathan Silva, Júlia Campos, Eduardo Sousa, H. Silva, Karina B. Angilelli, A. Mantovani, Rafael Mantovani
Olive samples were subjected to the salting process in brine containing 1196 mol m-3 of NaCl and 402 mol m-3 of KCl. Samples were collected during 60 h and salt concentration values were determined. With the finite element method (FEM) and the minimization of the errors percentage between the simulated and experimental values, the mass transfer coefficients in the film (hm) were obtained, being 1.0072 × 10-8 and 1.2499 × 10-8 for NaCl and KCl, respectively. The salts concentration at the olive/brine interface was simulated by FEM and analyzed via SOFM. A network with 4 × 4 topology and 10000 training epochs was used. It was observed that the influence of the stationary film formed on the surface of the olives during the salting process depends on the position, the salt involved in the diffusion and that the concentration of the salts, at each point, varies according to the immersion time.
{"title":"DIFFUSION STUDY OF NaCl AND KCl AT THE SOLUTION/OLIVE INTERFACE: MATHEMATICAL MODELING USING THE FINITE ELEMENT METHOD AND SELF-ORGANIZING FEATURE MAP (SOFM)-TYPE NEURAL NETWORKS","authors":"D. Borsato, M. Clemente, Heloisa Silva, Nathan Silva, Júlia Campos, Eduardo Sousa, H. Silva, Karina B. Angilelli, A. Mantovani, Rafael Mantovani","doi":"10.21577/0100-4042.20230053","DOIUrl":"https://doi.org/10.21577/0100-4042.20230053","url":null,"abstract":"Olive samples were subjected to the salting process in brine containing 1196 mol m-3 of NaCl and 402 mol m-3 of KCl. Samples were collected during 60 h and salt concentration values were determined. With the finite element method (FEM) and the minimization of the errors percentage between the simulated and experimental values, the mass transfer coefficients in the film (hm) were obtained, being 1.0072 × 10-8 and 1.2499 × 10-8 for NaCl and KCl, respectively. The salts concentration at the olive/brine interface was simulated by FEM and analyzed via SOFM. A network with 4 × 4 topology and 10000 training epochs was used. It was observed that the influence of the stationary film formed on the surface of the olives during the salting process depends on the position, the salt involved in the diffusion and that the concentration of the salts, at each point, varies according to the immersion time.","PeriodicalId":49641,"journal":{"name":"Quimica Nova","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68272384","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-09DOI: 10.21577/0100-4042.20230052
Daiane Machado, R. D. de Oliveira
Brazil is the largest coffee producer in the world, and together with the millions of tons produced, millions of tons of residues are also generated. The generated residues are a source of environmental contamination depending on the chosen processing route. One of the main applications of food industry waste is in the production of raw materials to produce edible films and coatings. Coffee mucilage is a pectin-rich liquid residue from the coffee sector that can be used in the production of value-added products. Given this, the objective of this work was to characterize and evaluate the potential of functional and technological properties of coffee mucilage and your applicability in the production of edible films. The filmogenic mixture was obtained by casting from 10% (w/v) lyophilized coffee mucilage and solvent (water). The films produced from the coffee mucilage presented good homogeneity, continuity (absence of ruptures or fragile regions), flexibility, ease of detachment of the support and handling, without the need to add adjuvant to its formation. In addition, they presented uniformity in thickness, high light barrier and medium water vapor barrier. Thus, it can be concluded that mucilage is a potential product to be used in the cosmetic, pharmaceutical and food industries.
{"title":"FUNCTIONAL AND TECHNOLOGICAL PROPERTIES OF COFFEE MUCILAGE (Coffea arabica) AND ITS APPLICATION IN EDIBLE FILMS","authors":"Daiane Machado, R. D. de Oliveira","doi":"10.21577/0100-4042.20230052","DOIUrl":"https://doi.org/10.21577/0100-4042.20230052","url":null,"abstract":"Brazil is the largest coffee producer in the world, and together with the millions of tons produced, millions of tons of residues are also generated. The generated residues are a source of environmental contamination depending on the chosen processing route. One of the main applications of food industry waste is in the production of raw materials to produce edible films and coatings. Coffee mucilage is a pectin-rich liquid residue from the coffee sector that can be used in the production of value-added products. Given this, the objective of this work was to characterize and evaluate the potential of functional and technological properties of coffee mucilage and your applicability in the production of edible films. The filmogenic mixture was obtained by casting from 10% (w/v) lyophilized coffee mucilage and solvent (water). The films produced from the coffee mucilage presented good homogeneity, continuity (absence of ruptures or fragile regions), flexibility, ease of detachment of the support and handling, without the need to add adjuvant to its formation. In addition, they presented uniformity in thickness, high light barrier and medium water vapor barrier. Thus, it can be concluded that mucilage is a potential product to be used in the cosmetic, pharmaceutical and food industries.","PeriodicalId":49641,"journal":{"name":"Quimica Nova","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68272608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-09DOI: 10.21577/0100-4042.20230057
M. Pereira, R. Quero, Dosil Pereira De Jesus, Juliano Bonacin
DETAILED GUIDE TO OWN ASSEMBLY OF 3D PRINTERS. In recent years, there has been an increase in the use of 3D printing for the manufacture of three-dimensional objects. Thus, it is clear that 3D printers have presented as a tool with high potential for applications in several fields, including chemistry. However, despite its popularity, it is notable that some 3D printers have a relatively high cost, in addition to not favoring optimizations or repairs, making users dependent on the manufacturers of such tools. Therefore, this article aims to present, particularly to the chemistry community, a detailed guide for assembling a low-cost FDM-type 3D printer with good performance. Consequently, we hope that this guide can contribute to increasing the 3D printing popularization in the field of chemistry because of the various possibilities of applications in this area.
{"title":"GUIA DETALHADO PARA MONTAGEM PRÓPRIA DE IMPRESSORAS 3D","authors":"M. Pereira, R. Quero, Dosil Pereira De Jesus, Juliano Bonacin","doi":"10.21577/0100-4042.20230057","DOIUrl":"https://doi.org/10.21577/0100-4042.20230057","url":null,"abstract":"DETAILED GUIDE TO OWN ASSEMBLY OF 3D PRINTERS. In recent years, there has been an increase in the use of 3D printing for the manufacture of three-dimensional objects. Thus, it is clear that 3D printers have presented as a tool with high potential for applications in several fields, including chemistry. However, despite its popularity, it is notable that some 3D printers have a relatively high cost, in addition to not favoring optimizations or repairs, making users dependent on the manufacturers of such tools. Therefore, this article aims to present, particularly to the chemistry community, a detailed guide for assembling a low-cost FDM-type 3D printer with good performance. Consequently, we hope that this guide can contribute to increasing the 3D printing popularization in the field of chemistry because of the various possibilities of applications in this area.","PeriodicalId":49641,"journal":{"name":"Quimica Nova","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68272624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-09DOI: 10.21577/0100-4042.20230047
Pedro Paulo Da Silva, Flávio Schifino, C. Sirtori, C. Passos, N. Simon
AN ANALYSIS OF THE PROCESS OF DEVELOPING QUESTIONS PRODUCED BY CHEMISTRY STUDENTS IN A TEACHING PROGRAM BASED ON SCIENTIFIC COMMUNICATION LITERATURE. The objective of the present investigation was to evaluate the use of scientific dissemination literature (SDL) in the process of formulating questions developed by chemistry students in a Teaching Program in Chemistry. To this end, the book entitled The Disappearing Spoon was analyzed in terms of categories referring to format and content, while the 18 questions produced by these students about the chapters read were analyzed in terms of presupposition and request. The investigation was carried out with 16 undergraduates who were taking a theoretical course on “Introduction to Chemistry”, as part of the Teaching Program in Chemistry. According to the analysis carried out, some particularities of format, such as the scarcity of visual resources, the autonomous structure of the chapters and the language, may have influenced the elaborated presentations. It is interesting to note that almost half of the questions produced were of an investigative nature, demonstrating the potential of SDL to stimulate high cognitive skills. In addition, the questions with investigative requests were mostly opinion questions, which may have been motivated by characteristics of the text read, such as the content with a controversial approach used by the author, when reporting on some aspects of scientific activity.
{"title":"UMA ANÁLISE DO PROCESSO DE ELABORAÇÃO DE PERGUNTAS PRODUZIDAS POR LICENCIANDOS EM QUÍMICA A PARTIR DA LITERATURA DE DIVULGAÇÃO CIENTÍFICA","authors":"Pedro Paulo Da Silva, Flávio Schifino, C. Sirtori, C. Passos, N. Simon","doi":"10.21577/0100-4042.20230047","DOIUrl":"https://doi.org/10.21577/0100-4042.20230047","url":null,"abstract":"AN ANALYSIS OF THE PROCESS OF DEVELOPING QUESTIONS PRODUCED BY CHEMISTRY STUDENTS IN A TEACHING PROGRAM BASED ON SCIENTIFIC COMMUNICATION LITERATURE. The objective of the present investigation was to evaluate the use of scientific dissemination literature (SDL) in the process of formulating questions developed by chemistry students in a Teaching Program in Chemistry. To this end, the book entitled The Disappearing Spoon was analyzed in terms of categories referring to format and content, while the 18 questions produced by these students about the chapters read were analyzed in terms of presupposition and request. The investigation was carried out with 16 undergraduates who were taking a theoretical course on “Introduction to Chemistry”, as part of the Teaching Program in Chemistry. According to the analysis carried out, some particularities of format, such as the scarcity of visual resources, the autonomous structure of the chapters and the language, may have influenced the elaborated presentations. It is interesting to note that almost half of the questions produced were of an investigative nature, demonstrating the potential of SDL to stimulate high cognitive skills. In addition, the questions with investigative requests were mostly opinion questions, which may have been motivated by characteristics of the text read, such as the content with a controversial approach used by the author, when reporting on some aspects of scientific activity.","PeriodicalId":49641,"journal":{"name":"Quimica Nova","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68271799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-09DOI: 10.21577/0100-4042.20230044
N. Silva, Carolina Sotério, Fernanda Canduri, S. Queiroz
THE BIOCHEMISTRY BEHIND COVID-19: WEBQUEST DEVELOPMENT AND APPLICATION FOR EMERGENCY REMOTE TEACHING. WebQuests are inquiry-oriented activities structured in such a way that almost all resources used come from the web. The present study aims to investigate to what extent a WebQuest focusing on Biochemistry and COVID-19 can be used as an instructive tool to enhance undergraduate students’ media and information literacy (MIL). Students’ opinions on the use of the WebQuest were also discussed. The WebQuest was implemented in a BSc in Physical and Biomolecular Sciences course in the context of the COVID-19 pandemic. Based on the results of this study, the WebQuest has improved the MIL competence of students and motivated them towards learning Biochemistry.
{"title":"A BIOQUÍMICA POR TRÁS DA COVID-19: DESENVOLVIMENTO E APLICAÇÃO DE WEBQUEST DIRECIONADA AO ENSINO REMOTO EMERGENCIAL","authors":"N. Silva, Carolina Sotério, Fernanda Canduri, S. Queiroz","doi":"10.21577/0100-4042.20230044","DOIUrl":"https://doi.org/10.21577/0100-4042.20230044","url":null,"abstract":"THE BIOCHEMISTRY BEHIND COVID-19: WEBQUEST DEVELOPMENT AND APPLICATION FOR EMERGENCY REMOTE TEACHING. WebQuests are inquiry-oriented activities structured in such a way that almost all resources used come from the web. The present study aims to investigate to what extent a WebQuest focusing on Biochemistry and COVID-19 can be used as an instructive tool to enhance undergraduate students’ media and information literacy (MIL). Students’ opinions on the use of the WebQuest were also discussed. The WebQuest was implemented in a BSc in Physical and Biomolecular Sciences course in the context of the COVID-19 pandemic. Based on the results of this study, the WebQuest has improved the MIL competence of students and motivated them towards learning Biochemistry.","PeriodicalId":49641,"journal":{"name":"Quimica Nova","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68271806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-28DOI: 10.21577/0100-4042.20230041
Methanol present in wastewater from the biodiesel industry can become an atmospheric pollutant and an environmental liability of effluents. This article proposes the development and performance evaluation of two spectroscopic methods, ATR-FTIR and UV-Vis, to identify and quantify methanol in aqueous media. The results of both ways exhibited remarkable linear detection, with a coefficient of determination (r2) > 0.99, wide working range, and relative standard deviation (RSD) < 12%. In the ATR-FTIR method, the detection and quantification limits were 0.064 and 0.128% m V-1, respectively. The UV-Vis method presented lower limits (0.005 and 0.008% m V-1, respectively). Finally, the methods were successfully applied to quickly and sensitively quantify the methanol present in wastewater from biodiesel-washing in a wide concentration range of 0.008-0.641% m V-1. Therefore, we evidenced the feasibility of spectroscopic methods in quality control for identifying and quantifying methanol in aqueous solution, with potential for application in biodiesel production industries and research laboratories. Mainly by ATR-FTIR, in the region of 1300-900 cm-1, as it proved to be more environmentally friendly, faster, and cheaper than the GC-FID method.
生物柴油工业废水中存在的甲醇可能成为大气污染物和废水的环境负担。本文提出了ATR-FTIR和UV-Vis两种光谱方法的发展和性能评价，用于鉴别和定量水介质中的甲醇。两种方法均具有良好的线性检测效果，检测系数(r2)均为0.99，工作范围宽，相对标准偏差(RSD) < 12%。在ATR-FTIR方法中，检测限和定量限分别为0.064和0.128% m V-1。紫外可见法的下限分别为0.005 m V-1和0.008% m V-1。最后，这些方法成功地用于快速、灵敏地定量生物柴油洗涤废水中存在的甲醇，浓度范围为0.008-0.641% m V-1。因此，我们证明了光谱方法在鉴别和定量水溶液中甲醇的质量控制中的可行性，具有应用于生物柴油生产行业和研究实验室的潜力。主要是通过ATR-FTIR，在1300-900 cm-1范围内，因为它被证明比GC-FID方法更环保，更快，更便宜。
{"title":"ATR-FTIR AND UV-VIS AS TECHNIQUES FOR METHANOL ANALYSIS IN BIODIESEL-WASHING WASTEWATER","authors":"","doi":"10.21577/0100-4042.20230041","DOIUrl":"https://doi.org/10.21577/0100-4042.20230041","url":null,"abstract":"Methanol present in wastewater from the biodiesel industry can become an atmospheric pollutant and an environmental liability of effluents. This article proposes the development and performance evaluation of two spectroscopic methods, ATR-FTIR and UV-Vis, to identify and quantify methanol in aqueous media. The results of both ways exhibited remarkable linear detection, with a coefficient of determination (r2) > 0.99, wide working range, and relative standard deviation (RSD) < 12%. In the ATR-FTIR method, the detection and quantification limits were 0.064 and 0.128% m V-1, respectively. The UV-Vis method presented lower limits (0.005 and 0.008% m V-1, respectively). Finally, the methods were successfully applied to quickly and sensitively quantify the methanol present in wastewater from biodiesel-washing in a wide concentration range of 0.008-0.641% m V-1. Therefore, we evidenced the feasibility of spectroscopic methods in quality control for identifying and quantifying methanol in aqueous solution, with potential for application in biodiesel production industries and research laboratories. Mainly by ATR-FTIR, in the region of 1300-900 cm-1, as it proved to be more environmentally friendly, faster, and cheaper than the GC-FID method.","PeriodicalId":49641,"journal":{"name":"Quimica Nova","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68271517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-28DOI: 10.21577/0100-4042.20230034
Marcus Arantes, W. Günther
THE BEST SUSTAINABLE PRACTICES FOR CHEMICAL WASTE MANAGEMENT IN PUBLIC HIGHER EDUCATION INSTITUTIONS. This work proposes the minimum items for the composition of the best sustainable practices for chemical waste management in higher education institutions (HEI). It was made a bibliographical and documentary review of the Brazilian legislation applicable to the management of chemical waste, with the aim of supporting the elaboration of the best sustainable practices for chemical waste management and propose to assist the technical managers of HEI in the implementation of sustainable and safe management of chemical waste.
{"title":"BOAS PRÁTICAS SUSTENTÁVEIS DE GESTÃO DE RESÍDUOS QUÍMICOS EM INSTITUIÇÕES PÚBLICAS DE ENSINO SUPERIOR","authors":"Marcus Arantes, W. Günther","doi":"10.21577/0100-4042.20230034","DOIUrl":"https://doi.org/10.21577/0100-4042.20230034","url":null,"abstract":"THE BEST SUSTAINABLE PRACTICES FOR CHEMICAL WASTE MANAGEMENT IN PUBLIC HIGHER EDUCATION INSTITUTIONS. This work proposes the minimum items for the composition of the best sustainable practices for chemical waste management in higher education institutions (HEI). It was made a bibliographical and documentary review of the Brazilian legislation applicable to the management of chemical waste, with the aim of supporting the elaboration of the best sustainable practices for chemical waste management and propose to assist the technical managers of HEI in the implementation of sustainable and safe management of chemical waste.","PeriodicalId":49641,"journal":{"name":"Quimica Nova","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68271281","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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