Pub Date : 2023-05-26DOI: 10.21577/0103-5053.20220156
N. Nunes, M. T. Santos, Angela Martins
Biochars from peanut shell wastes were produced and further modified with KOH and HNO3 to efficiently remove two industrial dyes, Mordant Orange 1 and Green Malachite oxalate, in aqueous systems. The materials were characterized through elemental analysis, N2 adsorption isotherms, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and the determination of the point of zero charge, pHPZC. The basic and, particularly, the acid treatments increased the specific surface area by 15 and 43%, respectively, and the pHPZC shifted from 6.2 to 9.1 or 3.3 upon treatments with KOH or HNO3. These modifications impacted the adsorption behavior of the dyes; in the case of Mordant Orange 1, the adsorption capacity increased 2 and 4 times, respectively, when compared with the parent biochar. These results show that the performance of biochars can improve substantially through simple modifications using acid or basic treatments that not only increase the specific surface area but also modify adsorbent/adsorbate interactions.
{"title":"Low Cost Modified Biochars from Peanut Shells for the Removal of Textile Dyes","authors":"N. Nunes, M. T. Santos, Angela Martins","doi":"10.21577/0103-5053.20220156","DOIUrl":"https://doi.org/10.21577/0103-5053.20220156","url":null,"abstract":"Biochars from peanut shell wastes were produced and further modified with KOH and HNO3 to efficiently remove two industrial dyes, Mordant Orange 1 and Green Malachite oxalate, in aqueous systems. The materials were characterized through elemental analysis, N2 adsorption isotherms, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and the determination of the point of zero charge, pHPZC. The basic and, particularly, the acid treatments increased the specific surface area by 15 and 43%, respectively, and the pHPZC shifted from 6.2 to 9.1 or 3.3 upon treatments with KOH or HNO3. These modifications impacted the adsorption behavior of the dyes; in the case of Mordant Orange 1, the adsorption capacity increased 2 and 4 times, respectively, when compared with the parent biochar. These results show that the performance of biochars can improve substantially through simple modifications using acid or basic treatments that not only increase the specific surface area but also modify adsorbent/adsorbate interactions.","PeriodicalId":17257,"journal":{"name":"Journal of the Brazilian Chemical Society","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68328997","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 : 2023-05-26DOI: 10.21577/0103-5053.20220146
Gabriela P. Oliveira, T. Neves, L. Peixoto, S. Landi, B. Archanjo, Gustavo F. S. Andrade
The plasmonic properties of Au nanoparticles (AuNP), which allow the observation of enhanced spectroscopic effects, are strongly affected by the aggregation and precipitation caused by the strong interactions between nanoparticles. To avoid AuNP aggregation and precipitation, the present study proposes coating with MnO2, forming AuNP@MnO2 core-shell structures. The MnO2 layers presented 1-10 nm thickness so that highly surface-enhanced fluorescence was obtained with maximum intensity given by 5 nm thick MnO2. The decrease in Raman intensity could be controlled, despite the inherent reduction in surface-enhanced Raman scattering (SERS) intensity with increasing adsorbate-surface distance. The decrease in Raman intensity was compensated by increasing AuNP stability caused by the MnO2 shell.
{"title":"Synthesis and Characterization of Au@MnO2 Nanoparticles as Plasmon Enhanced Spectroscopy Substrates","authors":"Gabriela P. Oliveira, T. Neves, L. Peixoto, S. Landi, B. Archanjo, Gustavo F. S. Andrade","doi":"10.21577/0103-5053.20220146","DOIUrl":"https://doi.org/10.21577/0103-5053.20220146","url":null,"abstract":"The plasmonic properties of Au nanoparticles (AuNP), which allow the observation of enhanced spectroscopic effects, are strongly affected by the aggregation and precipitation caused by the strong interactions between nanoparticles. To avoid AuNP aggregation and precipitation, the present study proposes coating with MnO2, forming AuNP@MnO2 core-shell structures. The MnO2 layers presented 1-10 nm thickness so that highly surface-enhanced fluorescence was obtained with maximum intensity given by 5 nm thick MnO2. The decrease in Raman intensity could be controlled, despite the inherent reduction in surface-enhanced Raman scattering (SERS) intensity with increasing adsorbate-surface distance. The decrease in Raman intensity was compensated by increasing AuNP stability caused by the MnO2 shell.","PeriodicalId":17257,"journal":{"name":"Journal of the Brazilian Chemical Society","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68328387","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 : 2023-05-26DOI: 10.21577/0103-5053.20220149
C. Prates, A. Lima, I. Ferreira, Fabiano G F de Paula, Paula S. Pinto, J. Ardisson, R. Lago, A. Teixeira
In this work, iron ore tailing (IOT) was used for the production of two different materials: sodium silicate and geopolymers. Initially, reactions of IOT with NaOH were carried out by hydrothermal reaction in autoclave at 200 °C (1:1.5 and 1:2.5 SiO2:NaOH molar ratio) and reaction times of 4 and 8 h. X-ray fluorescence by dispersive energy (XRF), X-ray diffraction (XRD), Mössbauer spectroscopy, scanning electron microscopy (SEM-EDS) and titrations showed that IOT:NaOH ratios of 1:2.5 and reaction time 8 h completely dissolved the quartz from the IOT, obtaining a solid fraction consisting mainly of hematite and an aqueous phase of sodium silicate, which showed contents of ca. 23% SiO2 and 19% Na2O. This sodium silicate obtained was then combined with IOT (25 and 50 wt.%) to produce geopolimeric material with excellent physicochemical properties, fast curing time and very good compressive strength results, which ranged from 41 to 58 MPa and many potential applications.
{"title":"Use of Iron Ore Tailing as Raw Material for Two Products: Sodium Silicate and Geopolymers","authors":"C. Prates, A. Lima, I. Ferreira, Fabiano G F de Paula, Paula S. Pinto, J. Ardisson, R. Lago, A. Teixeira","doi":"10.21577/0103-5053.20220149","DOIUrl":"https://doi.org/10.21577/0103-5053.20220149","url":null,"abstract":"In this work, iron ore tailing (IOT) was used for the production of two different materials: sodium silicate and geopolymers. Initially, reactions of IOT with NaOH were carried out by hydrothermal reaction in autoclave at 200 °C (1:1.5 and 1:2.5 SiO2:NaOH molar ratio) and reaction times of 4 and 8 h. X-ray fluorescence by dispersive energy (XRF), X-ray diffraction (XRD), Mössbauer spectroscopy, scanning electron microscopy (SEM-EDS) and titrations showed that IOT:NaOH ratios of 1:2.5 and reaction time 8 h completely dissolved the quartz from the IOT, obtaining a solid fraction consisting mainly of hematite and an aqueous phase of sodium silicate, which showed contents of ca. 23% SiO2 and 19% Na2O. This sodium silicate obtained was then combined with IOT (25 and 50 wt.%) to produce geopolimeric material with excellent physicochemical properties, fast curing time and very good compressive strength results, which ranged from 41 to 58 MPa and many potential applications.","PeriodicalId":17257,"journal":{"name":"Journal of the Brazilian Chemical Society","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68328210","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 : 2023-05-26DOI: 10.21577/0103-5053.20220148
Francineide Lopes de Araújo, A. Nogueira, J. D. de Freitas
Hybrid organic-inorganic perovskites have attracted interest in photovoltaic applications due to their excellent optoelectronic properties and low-temperature processability. From 2009 to 2021, lab-scale perovskite solar cells (PSC) reached a power conversion efficiency (PCE) of 25.7%, and a PCE of 17.9% for perovskite solar modules with an area of 800 cm2. Here, we present an investigation using three deposition techniques, spin-coating, blade-coating, and spraycoating, to process the charge transport layers and the active layer of perovskite solar cells onto 5 cm × 5 cm sized substrates, with device structure glass/fluorine-doped tin oxide (FTO)/c-TiO2/ meso-TiO2+Perovskite/2,2’,7,7’-tetrakis(N,N-di-p-methoxyphenyl-amine)9,9’-spirobifluorene (spiro-OMeTAD) or poly(3-hexylthiophene) (P3HT)/Au. Large-area PSC achieved an opencircuit voltage of around 1.1 V and PCE of 6%. The power generated was sufficient to start a fan. Furthermore, the connection in series of two large-area PSCs generated a voltage of 1.9 V. Then, we developed a simple method for manufacturing a monolithic perovskite mini-module containing two series-connected PSCs without using laser-scribing processes (usually named P1, P2, and P3 processes). This mini-module delivered a voltage of 1.52 V. Both voltages (1.9 and 1.52 V) were enough to turn on a red (or yellow) light-emitting diode (LED). To our knowledge, this is the first scientific report describing the assembly of a large-area n-i-p perovskite single cell and mini-module in Brazil.
{"title":"Facile Methods for the Assembly of Large-Area Perovskite Solar Cells and Mini‑Module: A Step-by-Step Description of Layers Processing","authors":"Francineide Lopes de Araújo, A. Nogueira, J. D. de Freitas","doi":"10.21577/0103-5053.20220148","DOIUrl":"https://doi.org/10.21577/0103-5053.20220148","url":null,"abstract":"Hybrid organic-inorganic perovskites have attracted interest in photovoltaic applications due to their excellent optoelectronic properties and low-temperature processability. From 2009 to 2021, lab-scale perovskite solar cells (PSC) reached a power conversion efficiency (PCE) of 25.7%, and a PCE of 17.9% for perovskite solar modules with an area of 800 cm2. Here, we present an investigation using three deposition techniques, spin-coating, blade-coating, and spraycoating, to process the charge transport layers and the active layer of perovskite solar cells onto 5 cm × 5 cm sized substrates, with device structure glass/fluorine-doped tin oxide (FTO)/c-TiO2/ meso-TiO2+Perovskite/2,2’,7,7’-tetrakis(N,N-di-p-methoxyphenyl-amine)9,9’-spirobifluorene (spiro-OMeTAD) or poly(3-hexylthiophene) (P3HT)/Au. Large-area PSC achieved an opencircuit voltage of around 1.1 V and PCE of 6%. The power generated was sufficient to start a fan. Furthermore, the connection in series of two large-area PSCs generated a voltage of 1.9 V. Then, we developed a simple method for manufacturing a monolithic perovskite mini-module containing two series-connected PSCs without using laser-scribing processes (usually named P1, P2, and P3 processes). This mini-module delivered a voltage of 1.52 V. Both voltages (1.9 and 1.52 V) were enough to turn on a red (or yellow) light-emitting diode (LED). To our knowledge, this is the first scientific report describing the assembly of a large-area n-i-p perovskite single cell and mini-module in Brazil.","PeriodicalId":17257,"journal":{"name":"Journal of the Brazilian Chemical Society","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68328512","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 : 2023-05-26DOI: 10.21577/0103-5053.20220155
Maximiliano D. Martins, T. Aversa, C. M. D. da Silva, E. D. da Silva, E. Lucas
Cardanol acts to stabilize asphaltene particles in crude oil, but its derivative polycardanol, synthesized with BF3.O(C2H5)2 as initiator, exhibits divergent behavior, acting as both asphaltenes stabilizer and flocculant. This behavior could be related to structural differences in polycardanol samples. Therefore, in this work, we study the influence of some polymerization conditions (monomer purity, initiator concentration, and reaction time) on the structures and molar masses of the reaction products, and the reaction conversion. The materials were characterized by size‑exclusion chromatography and hydrogen and carbon nuclear magnetic resonance. When reacting with distilled cardanol, the conversion, the molar mass, and the homogeneity of structures increased as increasing initiator concentration in the range tested (1-3% m/m). For both monomers (different purity degrees), when using a lower initiator concentration (1% m/m), the product contained a larger amount of unreacted monomer and different structures were obtained due to the occurrence of rearrangements. The presence of triolefinic molecules in the monomer provoked crosslinked structures for higher initiator concentration (2-3% m/m). This study elucidated the differences among the reaction products of polycardanol.
{"title":"Synthesis of Polycardanol Using BF3.O(C2H5)2 as Initiator: Influence of Polymerization Conditions on Reaction Products","authors":"Maximiliano D. Martins, T. Aversa, C. M. D. da Silva, E. D. da Silva, E. Lucas","doi":"10.21577/0103-5053.20220155","DOIUrl":"https://doi.org/10.21577/0103-5053.20220155","url":null,"abstract":"Cardanol acts to stabilize asphaltene particles in crude oil, but its derivative polycardanol, synthesized with BF3.O(C2H5)2 as initiator, exhibits divergent behavior, acting as both asphaltenes stabilizer and flocculant. This behavior could be related to structural differences in polycardanol samples. Therefore, in this work, we study the influence of some polymerization conditions (monomer purity, initiator concentration, and reaction time) on the structures and molar masses of the reaction products, and the reaction conversion. The materials were characterized by size‑exclusion chromatography and hydrogen and carbon nuclear magnetic resonance. When reacting with distilled cardanol, the conversion, the molar mass, and the homogeneity of structures increased as increasing initiator concentration in the range tested (1-3% m/m). For both monomers (different purity degrees), when using a lower initiator concentration (1% m/m), the product contained a larger amount of unreacted monomer and different structures were obtained due to the occurrence of rearrangements. The presence of triolefinic molecules in the monomer provoked crosslinked structures for higher initiator concentration (2-3% m/m). This study elucidated the differences among the reaction products of polycardanol.","PeriodicalId":17257,"journal":{"name":"Journal of the Brazilian Chemical Society","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68328989","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 : 2023-05-26DOI: 10.21577/0103-5053.20220147
R. Rial, T. Merlo, P. Santos, Luiz Felipe Dias Melo, O. D. de Freitas, R. Barbosa, C. E. Nazário, L. H. Viana
Cagaiteira, the fruit popularly known as cagaite, belongs to the Myrtaceae family. Seed oil cagaite (Eugenia dysenterica DC) was obtained by three methods of extraction, extraction using an ultrasound (OCU), extraction by mechanical pressing (OCP) and extraction with Soxhlet extractor (OCS) in 3 different times (3, 6 and 9 h) and the content of fatty acids and physicalchemical properties were compared. The rate of saturated fatty acids ranged from 19.46% (OCP03) to 31.18% (OCS09), while the amount of unsaturated fatty acids ranged from 54.72% (OCP03) to 67.64% (OCS09). Linoleic and linolenic acids, important in nutrition food, varied between 32.22- 38.11 and 5.55-8.78%. For oxidative stability, OCUAq (heated ultrasound extraction) samples showed the highest induction periods, showing a positive correlation with antioxidant activity and phenol content, demonstrating the efficiency of the use of ultrasonic extraction to obtain quality oils from cagaite seeds.
{"title":"Fatty Acid Content and Physicalchemical Properties of Cagaite Seed Oil (Eugenia dysenterica DC) Obtained by Different Extraction Methods","authors":"R. Rial, T. Merlo, P. Santos, Luiz Felipe Dias Melo, O. D. de Freitas, R. Barbosa, C. E. Nazário, L. H. Viana","doi":"10.21577/0103-5053.20220147","DOIUrl":"https://doi.org/10.21577/0103-5053.20220147","url":null,"abstract":"Cagaiteira, the fruit popularly known as cagaite, belongs to the Myrtaceae family. Seed oil cagaite (Eugenia dysenterica DC) was obtained by three methods of extraction, extraction using an ultrasound (OCU), extraction by mechanical pressing (OCP) and extraction with Soxhlet extractor (OCS) in 3 different times (3, 6 and 9 h) and the content of fatty acids and physicalchemical properties were compared. The rate of saturated fatty acids ranged from 19.46% (OCP03) to 31.18% (OCS09), while the amount of unsaturated fatty acids ranged from 54.72% (OCP03) to 67.64% (OCS09). Linoleic and linolenic acids, important in nutrition food, varied between 32.22- 38.11 and 5.55-8.78%. For oxidative stability, OCUAq (heated ultrasound extraction) samples showed the highest induction periods, showing a positive correlation with antioxidant activity and phenol content, demonstrating the efficiency of the use of ultrasonic extraction to obtain quality oils from cagaite seeds.","PeriodicalId":17257,"journal":{"name":"Journal of the Brazilian Chemical Society","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68328408","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 : 2023-05-26DOI: 10.21577/0103-5053.20220154
Jing Hu, Tong Yang, Zhengjia Li, Bo Xiao, Peng Yu
The mutations of breast cancer susceptibility gene 1 (BRCA1) play an important role in inherited breast cancers. Thus, the sensitive assay of the BRCA1 gene is extremely important for disease diagnosis and human health. Herein, a fast, sensitive and selective assay technique has been constructed based on fluorescent copper nanoclusters (CuNCs). The CuNCs were successfully formed with poly(AT-TA) double stranded DNA (dsDNA) as template. In the absence of the target, a strong red emission was observed under 365 nm ultraviolet (UV) lamp and a big fluorescence response was obtained. However, in the presence of BRCA1 gene, there was only weak red emission and a low response signal was produced because of the target-proximity induced quenching of the fluorescence of CuNCs. The linear range for the BRCA1 gene assay was 2-600 nM, and the limit of detection was 2 nM. The assay technique showed good selectivity, good stability and satisfactory recoveries for the detection of BRCA1 gene in diluted serum samples. Moreover, by integrating a UV lamp and a smartphone, the fluorescence sensor would be transferred to a microfluidic chip, providing a prospective application in point-of-care for monitoring breast cancer risk.
{"title":"Sensitive Detection of BRCA1 Gene Based on Target Proximity Induced Quenching of the Fluorescence of Copper Nanoclusters","authors":"Jing Hu, Tong Yang, Zhengjia Li, Bo Xiao, Peng Yu","doi":"10.21577/0103-5053.20220154","DOIUrl":"https://doi.org/10.21577/0103-5053.20220154","url":null,"abstract":"The mutations of breast cancer susceptibility gene 1 (BRCA1) play an important role in inherited breast cancers. Thus, the sensitive assay of the BRCA1 gene is extremely important for disease diagnosis and human health. Herein, a fast, sensitive and selective assay technique has been constructed based on fluorescent copper nanoclusters (CuNCs). The CuNCs were successfully formed with poly(AT-TA) double stranded DNA (dsDNA) as template. In the absence of the target, a strong red emission was observed under 365 nm ultraviolet (UV) lamp and a big fluorescence response was obtained. However, in the presence of BRCA1 gene, there was only weak red emission and a low response signal was produced because of the target-proximity induced quenching of the fluorescence of CuNCs. The linear range for the BRCA1 gene assay was 2-600 nM, and the limit of detection was 2 nM. The assay technique showed good selectivity, good stability and satisfactory recoveries for the detection of BRCA1 gene in diluted serum samples. Moreover, by integrating a UV lamp and a smartphone, the fluorescence sensor would be transferred to a microfluidic chip, providing a prospective application in point-of-care for monitoring breast cancer risk.","PeriodicalId":17257,"journal":{"name":"Journal of the Brazilian Chemical Society","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68328940","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 : 2023-05-26DOI: 10.21577/0103-5053.20220150
Marco Antonio de Souza, A. Santos, Sebastião William da Silva, J. Braga, M. H. Sousa
Latent fingerprint is an important crime scene evidence, but it is not always recoverable or technically suitable for analysis with fingerprint patterns. Forensic science has shown that other information can be explored from traces using chemical compounds. Infrared spectroscopy is a nondestructive technique that is widely applied to a variety of forensic evidence. In this work, infrared spectroscopy and partial least square discriminant analysis were used to determine the human sex based on latent fingermark analysis. Fingerprint samples were taken from 42 male and female donors, then kept in either dark or light storage conditions, and the Fourier transform infrared (FTIR) spectra were measured considering a period of up to 30 days from collection. The regions from 3000 to 2800 cm-1 and 1790 to 1150 cm-1 presented the greatest differences in the peak intensities among the two sex groups. The results showed a correct discrimination rate higher than 80%.
{"title":"*e-mail: jez@unb.br Editor handled this article: Ivo M. Raimundo Jr. (Associate) Diffuse Reflectance FTIR of Latent Fingerprints and Discriminant Analysis for Sex Identification in Humans","authors":"Marco Antonio de Souza, A. Santos, Sebastião William da Silva, J. Braga, M. H. Sousa","doi":"10.21577/0103-5053.20220150","DOIUrl":"https://doi.org/10.21577/0103-5053.20220150","url":null,"abstract":"Latent fingerprint is an important crime scene evidence, but it is not always recoverable or technically suitable for analysis with fingerprint patterns. Forensic science has shown that other information can be explored from traces using chemical compounds. Infrared spectroscopy is a nondestructive technique that is widely applied to a variety of forensic evidence. In this work, infrared spectroscopy and partial least square discriminant analysis were used to determine the human sex based on latent fingermark analysis. Fingerprint samples were taken from 42 male and female donors, then kept in either dark or light storage conditions, and the Fourier transform infrared (FTIR) spectra were measured considering a period of up to 30 days from collection. The regions from 3000 to 2800 cm-1 and 1790 to 1150 cm-1 presented the greatest differences in the peak intensities among the two sex groups. The results showed a correct discrimination rate higher than 80%.","PeriodicalId":17257,"journal":{"name":"Journal of the Brazilian Chemical Society","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68329111","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 : 2023-05-01DOI: 10.21577/0103-5053.20220144
R. Motta, C. Dornelas, R.M. De Almeida
Catalysts were synthesized with Ni and bentonite clay, without previous treatment, through wet impregnation with 5, 10 and 20% of Ni (m/m). They were characterized by energy dispersive X-ray fluorescence spectrometry (EDX), X-ray diffraction (XRD), temperature-programmed reduction (TPR), thermogravimetric analysis (TGA), adsorption and desorption of N2 at 77 K, and transmission electron microscopy (TEM). The catalytic activity in relation to the methane conversion reaction was evaluated at 500 °C for 0.5 h. The addition of 10 and 20% of nickel to the clay led to a disordered bentonite structure, characterized by the disappearance of the 001 reflection on the X-ray diffractograms, with a consequent increase in the interaction between nickel oxide and clay (TPR). All catalysts synthesized showed catalytic activity in relation to the conversion of methane to form ordered carbon. The catalyst with 20% of nickel had the highest activity, with 74% of methane conversion.
{"title":"Nickel Nanoparticles Anchored on Bentonite Clay for Methane Decomposition with Ordered Carbon as a Product","authors":"R. Motta, C. Dornelas, R.M. De Almeida","doi":"10.21577/0103-5053.20220144","DOIUrl":"https://doi.org/10.21577/0103-5053.20220144","url":null,"abstract":"Catalysts were synthesized with Ni and bentonite clay, without previous treatment, through wet impregnation with 5, 10 and 20% of Ni (m/m). They were characterized by energy dispersive X-ray fluorescence spectrometry (EDX), X-ray diffraction (XRD), temperature-programmed reduction (TPR), thermogravimetric analysis (TGA), adsorption and desorption of N2 at 77 K, and transmission electron microscopy (TEM). The catalytic activity in relation to the methane conversion reaction was evaluated at 500 °C for 0.5 h. The addition of 10 and 20% of nickel to the clay led to a disordered bentonite structure, characterized by the disappearance of the 001 reflection on the X-ray diffractograms, with a consequent increase in the interaction between nickel oxide and clay (TPR). All catalysts synthesized showed catalytic activity in relation to the conversion of methane to form ordered carbon. The catalyst with 20% of nickel had the highest activity, with 74% of methane conversion.","PeriodicalId":17257,"journal":{"name":"Journal of the Brazilian Chemical Society","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68328526","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 : 2023-05-01DOI: 10.21577/0103-5053.20220140
Raissa T Franco, Ana Luisa Silva, Yordy E. Licea, M. Alzamora, Dalber R Sánchez, Nakédia M. F. Carvalho
Sustainable and environmentally friendly methods for nanomaterials synthesis have been emerging recently. The use of extracts of polyphenol-rich plants with high reducing and chelating power is advantageous because the polyphenol can protect the nanomaterial from agglomeration and deactivation. Green nanomaterials have been applied in several areas, including remediation of toxic organic pollutants from contaminated effluents. Herein, we describe the preparation of green iron oxide nanoparticles (IONPs) with extracts of the plant Camellia sinensis as black tea for dye removal application. The as-prepared IONPs were composed of amorphous FeOOH and FeII/III-polyphenol complexes. To obtain crystalline and pure iron-based nanomaterials, the amorphous precursor was annealed at 900 ºC. Samples of black tea from different regions were used to verify the reproducibility of the iron phases formed. The same iron phases were obtained for all black tea samples, α-Fe2O3 (hematite), FePO4, and Fe3PO7, but in different proportions. The materials were applied as heterogeneous-Fenton catalysts for the removal of the dye methyl orange. The amorphous as-prepared IONPs were more active than the respective annealed IONPs due to the proton release from the polyphenol into the reaction medium, setting the pH to around 3, which is the optimum pH for the Fenton system.
近年来，可持续和环境友好的纳米材料合成方法不断涌现。利用高还原和螯合能力的富含多酚的植物提取物可以防止纳米材料团聚和失活。绿色纳米材料已在多个领域得到应用，包括污染废水中有毒有机污染物的修复。在此，我们描述了用茶树提取物制备绿色氧化铁纳米颗粒(IONPs)用于去除染料。所制备的离子卟啉由FeOOH和FeII/ iii -多酚络合物组成。为了获得结晶和纯铁基纳米材料，将非晶前驱体在900℃下退火。使用不同地区的红茶样品来验证所形成的铁相的可重复性。所有红茶样品α-Fe2O3(赤铁矿)、FePO4和Fe3PO7均获得相同的铁相，但比例不同。将这些材料作为多相fenton催化剂用于甲基橙染料的脱除。由于质子从多酚中释放到反应介质中，制备的无定形IONPs比相应的退火IONPs更活跃，pH值约为3，这是Fenton体系的最佳pH值。
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