The electrochemical behavior of a platinum electrode in a set of 1-alkyl ether (and 1-alkyl)-3-me... more The electrochemical behavior of a platinum electrode in a set of 1-alkyl ether (and 1-alkyl)-3-methylimidazolium room-temperature ionic liquids (RTILs) 1-3 ([C x O y Mim] + [Anion] − or [C x Mim] + [Anion] − , where Mim = 3-methylimidazolium; C x O y = 1-alkyl ether; C 7 O 3 =-(CH 2) 2 O(CH 2) 2 O(CH 2) 2 OCH 3 ; C 3 O 1 =-(CH 2) 2 OCH 3 ; C x = 1-alkyl; C 10 = C 10 H 21 ; C 4 = C 4 H 9 ; and Anion ½ À ¼ H 3 CSO À 3 ; BF À 4 ; or PF À 6) was studied by cyclic voltammetry and electrical conductivity. This complementary set of imidazolium RTILs allowed us to explore the effect of the imidazolium cation and the counter-ion, both of which affected the electrochemical window of these RTILs. Various electrochemical events with low current values were observed, which diminished the electrochemical windows. Interestingly, RTILs 2b [1-(2-methoxyethyl)-3-methylimi-dazolium tetrafluoroborate] and 2d [1-butyl-3-methylimidazolium tetrafluoroborate] showed quasireversible charge transfer processes. The length of the functional group attached to the imidazolium cation was shown to be of great influence as larger electrochemical windows, as well as lower electrical conductivities, were obtained with the longer C 7 O 3 and C 10 functional groups. The largest electrochemical window of 2.0 V was achieved with RTIL 2c, 1-decyl-3-methylimidazolium tetrafluoroborate.
... FA Pavan Universidade Federal do Pampa, Rua Carlos Barbosa s/n, Getúlio Vargas, CEP: 96412-42... more ... FA Pavan Universidade Federal do Pampa, Rua Carlos Barbosa s/n, Getúlio Vargas, CEP: 96412-420 Bage, RS, Brazil ... This structural organization of ILs can be used as ''entropic driver'' for spontaneous, well-defined and extended ordering of nano-scale structures. ...
Cyclic voltammetry measurements using a platinum electrode were performed to study the effect of ... more Cyclic voltammetry measurements using a platinum electrode were performed to study the effect of water when added to the imidazolium room-temperature ionic liquids (RTILs) 1 [C 7 O 3 MIm][Mes] and 2 [C 3 O 1 MIm][Mes]. The addition of a very small amount of water to RTIL 1 resulted in diminished cathodic current values. An even more pronounced effect was observed with RTIL 2 and all charge transfer processes were extremely reduced. This inhibition of the charge transfer processes suggests the formation of new species, due to a reaction between water and the RTILs, that adsorbs on the electrode surface.
Schrekker (orient.) (UFRGS). O projeto de pesquisa tem como objetivo o desenvolvimento de novos n... more Schrekker (orient.) (UFRGS). O projeto de pesquisa tem como objetivo o desenvolvimento de novos nanocompósitos poliméricos com sílica, utilizando líquidos iônicos como compatibilizantes. Isto, para desenvolver novas tecnologias e materiais de alto desempenho com propriedades físicas e químicas diferenciadas. Foi utilizado o líquido iônico 1-decil-3metilimidazólio tetrafluoroborato para a preparação de nanocompósitos de polipropileno com sílica. Este líquido iônico possui uma cadeia alifática, que é apolar, podendo interagir com o polímero apolar, enquanto que o anel imidazólio e o ânion tetrafluoroborato, que são polares, interagem com a sílica, que também é polar, como mostrado na Figura. A sílica com líquido iônico nos poros foi preparada pelo método SolGel, e misturada com o polipropileno no estado fundido em uma câmara de mistura. Foram feitas análises (MEV, DRX, MET, DSC, TGA, DMA, adsorção-dessorção de nitrogênio, MFA) para caracterizar as propriedades das sílicas e dos compósitos poliméricos. Obteve-se uma dispersão homogênea da sílica no polipropileno, e algumas propriedades do compósito polimérico foram modificadas devido à presença do líquido iônico e da sílica. Concluindo assim que o líquido iônico pode atuar como compatibilizante. (PIBIC).
A set of six imidazolium ionic liquids (1a-b, 2a-c, 3), that were solids at room temperature, wer... more A set of six imidazolium ionic liquids (1a-b, 2a-c, 3), that were solids at room temperature, were characterized by electrical impedance spectroscopy to obtain information about their polarization resistance (R p ), conductivity (s) and charge transfer activation energy (E a ). These experiments were performed at different temperatures in a glass micro-cell, equipped with three platinum electrodes. The observed conductivities were due to charge transfer processes of molecular oxygen at the electrode surface and mass transfer processes within the IL matrix. Higher temperatures resulted for all ionic liquids in increased conductivities. X-Ray diffraction of the ionic liquids 2a-c suggested that a higher degree of supramolecular two-dimensional organization, higher density, is related to an easier oxygen-electrode approximation, lower E a . Two distinct temperatures ranges were observed. The larger conductivity increases in the higher temperature range were explained by melting and fluxional behavior/reorientation phenomena of the ionic liquids and are due to enhanced oxygen diffusion (IL 3). In general, the understanding of imidazolium ionic liquid electrochemical properties could facilitate the development of new applications. a Activation energy calculated from the Arrhenius formula. b Temperature at the intersection of the low-and high-temperature range of the temperature dependent conductivity. c Melting point determined by differential scanning calorimetry on heating. d Ref. 42.
The use of bio oil of fast pyrolysis of agricultural and industrial residues may be an economical... more The use of bio oil of fast pyrolysis of agricultural and industrial residues may be an economically and environmentally friendly choice for generation of energy and also for the production of chemicals. Suitable applications of rice husk and peach pit are an important issue to avoid improper waste disposal, as Brazilian production of rice and peach reach significant values. The purpose of this work was to perform a detailed qualitative analysis of bio oils of rice husk and peach pit, taking advantage of the higher peak capacity, resolution, sensitivity and selectivity of two-dimensional gas chromatography with mass spectrometric detector (GC × GC/TOFMS). The total number of compounds detected by GC × GC/TOFMS was 503 and 705 for rice husk and peach pit pyrolysates, respectively. Compounds tentatively identified in the same matrices were 106 and 223, respectively. Bio oil compounds were classified in five groups: phenols ketones, acids, ethers, aldehydes, and others. Major classes of both bio oils were phenols and ketones and the major compounds of rice husk and peach pit pyrolysates were guaiacol and furfural, respectively. Twenty compounds (area > 1%) of rice husk bio oil and 25 of peach pit oil accounted for 74.04% and 63.62% of the total area, respectively. A structured distribution of compounds of some classes was observed in the two dimensional space, as for example phenols and ketones. Qualitative analysis of these bio oils by GC × GC provided a detailed knowledge of their composition. Both bio oils showed might be employed for the production of chemicals and may be upgraded through an improved pyrolysis process.
This work studied fast pyrolysis as a way to use the residual fiber obtained from the shells of c... more This work studied fast pyrolysis as a way to use the residual fiber obtained from the shells of coconut ( Cocos nucifera L. var. Dwarf, from Aracaju, northeastern Brazil). The bio-oil produced by fast pyrolysis and the aqueous phase (formed during the pyrolysis) were characterized by GC/qMS and GC×GC/TOF-MS. Many oxygenated compounds such as phenols, aldehydes, and ketones were identified in the extracts obtained in both phases, with a high predominance of phenolic compounds, mainly alkylphenols. Eighty-one compounds were identified in the bio-oil and 42 in the aqueous phase using GC/qMS, and 95 and 68 in the same samples were identified by GC×GC/TOF-MS. The better performance of GC×GC/TOF-MS was due to the possibility of resolving some coeluted peaks in the one-dimension gas chromatography. Semiquantitative analysis of the samples verified that 59% of the area on the chromatogram of bio-oil is composed by phenols and 12% by aldehydes, mainly furfural. Using the same criterion, 77% of the organic compounds in the aqueous phase are phenols. Therefore, this preliminary assessment indicates that coconut fibers have the potential to be a cost-effective and promising alternative to obtain new products and minimize environmental impact.
A set of four imidazolium ionic liquids (solid at room temperature) and one imidazolium ionic sol... more A set of four imidazolium ionic liquids (solid at room temperature) and one imidazolium ionic solid was screened for its potential as electrolytes in manganese dioxide free Leclanché batteries, equipped with a zinc anode and graphite cathode. Electrical impedance spectroscopy allowed to determine the room-temperature ionic solids (RTISs) ionic conductivities, which was the highest for carboxylic acid functionalized RTIS 3 [C 2 O 2 MIm][Cl]. The toxic manganese dioxide was substituted by benzoquinone. A systematic ionic conductivity optimization of RTIS 3-benzoquinone-ZnSO 4 -H 2 O mixtures at room temperature resulted in the identification of the following conditions for the Leclanché battery studies: 50 mg of a 50:50 RTIS:benzoquinone mixture and 96 mg of water. The chronopotentiometric experiments with a constant current of 5 lA showed a remarkable performance for the RTIS 3 based battery. The potential (1.47 V) and
Líquidos iônicos como compatibilizantes para a preparação de nanocompósitos poliméricos de poliol... more Líquidos iônicos como compatibilizantes para a preparação de nanocompósitos poliméricos de poliolefinas apolares e sílicas. ...
Cyclic voltammetry measurements using a platinum electrode were performed to study the effect of ... more Cyclic voltammetry measurements using a platinum electrode were performed to study the effect of water when added to the imidazolium room-temperature ionic liquids (RTILs) 1 [C 7 O 3 MIm][Mes] and 2 [C 3 O 1 MIm] [Mes]. The addition of a very small amount of water to RTIL 1 resulted in diminished cathodic current values. An even more pronounced effect was observed with RTIL 2 and all charge transfer processes were extremely reduced. This inhibition of the charge transfer processes suggests the formation of new species, due to a reaction between water and the RTILs, that adsorbs on the electrode surface.
The electrochemical behavior of a platinum electrode in a set of 1-alkyl ether (and 1-alkyl)-3-me... more The electrochemical behavior of a platinum electrode in a set of 1-alkyl ether (and 1-alkyl)-3-methylimidazolium room-temperature ionic liquids (RTILs) 1-3
The electrochemical behavior of a platinum electrode in a set of 1-alkyl ether (and 1-alkyl)-3-me... more The electrochemical behavior of a platinum electrode in a set of 1-alkyl ether (and 1-alkyl)-3-methylimidazolium room-temperature ionic liquids (RTILs) 1-3 ([C x O y Mim] + [Anion] − or [C x Mim] + [Anion] − , where Mim = 3-methylimidazolium; C x O y = 1-alkyl ether; C 7 O 3 =-(CH 2) 2 O(CH 2) 2 O(CH 2) 2 OCH 3 ; C 3 O 1 =-(CH 2) 2 OCH 3 ; C x = 1-alkyl; C 10 = C 10 H 21 ; C 4 = C 4 H 9 ; and Anion ½ À ¼ H 3 CSO À 3 ; BF À 4 ; or PF À 6) was studied by cyclic voltammetry and electrical conductivity. This complementary set of imidazolium RTILs allowed us to explore the effect of the imidazolium cation and the counter-ion, both of which affected the electrochemical window of these RTILs. Various electrochemical events with low current values were observed, which diminished the electrochemical windows. Interestingly, RTILs 2b [1-(2-methoxyethyl)-3-methylimi-dazolium tetrafluoroborate] and 2d [1-butyl-3-methylimidazolium tetrafluoroborate] showed quasireversible charge transfer processes. The length of the functional group attached to the imidazolium cation was shown to be of great influence as larger electrochemical windows, as well as lower electrical conductivities, were obtained with the longer C 7 O 3 and C 10 functional groups. The largest electrochemical window of 2.0 V was achieved with RTIL 2c, 1-decyl-3-methylimidazolium tetrafluoroborate.
... FA Pavan Universidade Federal do Pampa, Rua Carlos Barbosa s/n, Getúlio Vargas, CEP: 96412-42... more ... FA Pavan Universidade Federal do Pampa, Rua Carlos Barbosa s/n, Getúlio Vargas, CEP: 96412-420 Bage, RS, Brazil ... This structural organization of ILs can be used as ''entropic driver'' for spontaneous, well-defined and extended ordering of nano-scale structures. ...
Cyclic voltammetry measurements using a platinum electrode were performed to study the effect of ... more Cyclic voltammetry measurements using a platinum electrode were performed to study the effect of water when added to the imidazolium room-temperature ionic liquids (RTILs) 1 [C 7 O 3 MIm][Mes] and 2 [C 3 O 1 MIm][Mes]. The addition of a very small amount of water to RTIL 1 resulted in diminished cathodic current values. An even more pronounced effect was observed with RTIL 2 and all charge transfer processes were extremely reduced. This inhibition of the charge transfer processes suggests the formation of new species, due to a reaction between water and the RTILs, that adsorbs on the electrode surface.
Schrekker (orient.) (UFRGS). O projeto de pesquisa tem como objetivo o desenvolvimento de novos n... more Schrekker (orient.) (UFRGS). O projeto de pesquisa tem como objetivo o desenvolvimento de novos nanocompósitos poliméricos com sílica, utilizando líquidos iônicos como compatibilizantes. Isto, para desenvolver novas tecnologias e materiais de alto desempenho com propriedades físicas e químicas diferenciadas. Foi utilizado o líquido iônico 1-decil-3metilimidazólio tetrafluoroborato para a preparação de nanocompósitos de polipropileno com sílica. Este líquido iônico possui uma cadeia alifática, que é apolar, podendo interagir com o polímero apolar, enquanto que o anel imidazólio e o ânion tetrafluoroborato, que são polares, interagem com a sílica, que também é polar, como mostrado na Figura. A sílica com líquido iônico nos poros foi preparada pelo método SolGel, e misturada com o polipropileno no estado fundido em uma câmara de mistura. Foram feitas análises (MEV, DRX, MET, DSC, TGA, DMA, adsorção-dessorção de nitrogênio, MFA) para caracterizar as propriedades das sílicas e dos compósitos poliméricos. Obteve-se uma dispersão homogênea da sílica no polipropileno, e algumas propriedades do compósito polimérico foram modificadas devido à presença do líquido iônico e da sílica. Concluindo assim que o líquido iônico pode atuar como compatibilizante. (PIBIC).
A set of six imidazolium ionic liquids (1a-b, 2a-c, 3), that were solids at room temperature, wer... more A set of six imidazolium ionic liquids (1a-b, 2a-c, 3), that were solids at room temperature, were characterized by electrical impedance spectroscopy to obtain information about their polarization resistance (R p ), conductivity (s) and charge transfer activation energy (E a ). These experiments were performed at different temperatures in a glass micro-cell, equipped with three platinum electrodes. The observed conductivities were due to charge transfer processes of molecular oxygen at the electrode surface and mass transfer processes within the IL matrix. Higher temperatures resulted for all ionic liquids in increased conductivities. X-Ray diffraction of the ionic liquids 2a-c suggested that a higher degree of supramolecular two-dimensional organization, higher density, is related to an easier oxygen-electrode approximation, lower E a . Two distinct temperatures ranges were observed. The larger conductivity increases in the higher temperature range were explained by melting and fluxional behavior/reorientation phenomena of the ionic liquids and are due to enhanced oxygen diffusion (IL 3). In general, the understanding of imidazolium ionic liquid electrochemical properties could facilitate the development of new applications. a Activation energy calculated from the Arrhenius formula. b Temperature at the intersection of the low-and high-temperature range of the temperature dependent conductivity. c Melting point determined by differential scanning calorimetry on heating. d Ref. 42.
The use of bio oil of fast pyrolysis of agricultural and industrial residues may be an economical... more The use of bio oil of fast pyrolysis of agricultural and industrial residues may be an economically and environmentally friendly choice for generation of energy and also for the production of chemicals. Suitable applications of rice husk and peach pit are an important issue to avoid improper waste disposal, as Brazilian production of rice and peach reach significant values. The purpose of this work was to perform a detailed qualitative analysis of bio oils of rice husk and peach pit, taking advantage of the higher peak capacity, resolution, sensitivity and selectivity of two-dimensional gas chromatography with mass spectrometric detector (GC × GC/TOFMS). The total number of compounds detected by GC × GC/TOFMS was 503 and 705 for rice husk and peach pit pyrolysates, respectively. Compounds tentatively identified in the same matrices were 106 and 223, respectively. Bio oil compounds were classified in five groups: phenols ketones, acids, ethers, aldehydes, and others. Major classes of both bio oils were phenols and ketones and the major compounds of rice husk and peach pit pyrolysates were guaiacol and furfural, respectively. Twenty compounds (area > 1%) of rice husk bio oil and 25 of peach pit oil accounted for 74.04% and 63.62% of the total area, respectively. A structured distribution of compounds of some classes was observed in the two dimensional space, as for example phenols and ketones. Qualitative analysis of these bio oils by GC × GC provided a detailed knowledge of their composition. Both bio oils showed might be employed for the production of chemicals and may be upgraded through an improved pyrolysis process.
This work studied fast pyrolysis as a way to use the residual fiber obtained from the shells of c... more This work studied fast pyrolysis as a way to use the residual fiber obtained from the shells of coconut ( Cocos nucifera L. var. Dwarf, from Aracaju, northeastern Brazil). The bio-oil produced by fast pyrolysis and the aqueous phase (formed during the pyrolysis) were characterized by GC/qMS and GC×GC/TOF-MS. Many oxygenated compounds such as phenols, aldehydes, and ketones were identified in the extracts obtained in both phases, with a high predominance of phenolic compounds, mainly alkylphenols. Eighty-one compounds were identified in the bio-oil and 42 in the aqueous phase using GC/qMS, and 95 and 68 in the same samples were identified by GC×GC/TOF-MS. The better performance of GC×GC/TOF-MS was due to the possibility of resolving some coeluted peaks in the one-dimension gas chromatography. Semiquantitative analysis of the samples verified that 59% of the area on the chromatogram of bio-oil is composed by phenols and 12% by aldehydes, mainly furfural. Using the same criterion, 77% of the organic compounds in the aqueous phase are phenols. Therefore, this preliminary assessment indicates that coconut fibers have the potential to be a cost-effective and promising alternative to obtain new products and minimize environmental impact.
A set of four imidazolium ionic liquids (solid at room temperature) and one imidazolium ionic sol... more A set of four imidazolium ionic liquids (solid at room temperature) and one imidazolium ionic solid was screened for its potential as electrolytes in manganese dioxide free Leclanché batteries, equipped with a zinc anode and graphite cathode. Electrical impedance spectroscopy allowed to determine the room-temperature ionic solids (RTISs) ionic conductivities, which was the highest for carboxylic acid functionalized RTIS 3 [C 2 O 2 MIm][Cl]. The toxic manganese dioxide was substituted by benzoquinone. A systematic ionic conductivity optimization of RTIS 3-benzoquinone-ZnSO 4 -H 2 O mixtures at room temperature resulted in the identification of the following conditions for the Leclanché battery studies: 50 mg of a 50:50 RTIS:benzoquinone mixture and 96 mg of water. The chronopotentiometric experiments with a constant current of 5 lA showed a remarkable performance for the RTIS 3 based battery. The potential (1.47 V) and
Líquidos iônicos como compatibilizantes para a preparação de nanocompósitos poliméricos de poliol... more Líquidos iônicos como compatibilizantes para a preparação de nanocompósitos poliméricos de poliolefinas apolares e sílicas. ...
Cyclic voltammetry measurements using a platinum electrode were performed to study the effect of ... more Cyclic voltammetry measurements using a platinum electrode were performed to study the effect of water when added to the imidazolium room-temperature ionic liquids (RTILs) 1 [C 7 O 3 MIm][Mes] and 2 [C 3 O 1 MIm] [Mes]. The addition of a very small amount of water to RTIL 1 resulted in diminished cathodic current values. An even more pronounced effect was observed with RTIL 2 and all charge transfer processes were extremely reduced. This inhibition of the charge transfer processes suggests the formation of new species, due to a reaction between water and the RTILs, that adsorbs on the electrode surface.
The electrochemical behavior of a platinum electrode in a set of 1-alkyl ether (and 1-alkyl)-3-me... more The electrochemical behavior of a platinum electrode in a set of 1-alkyl ether (and 1-alkyl)-3-methylimidazolium room-temperature ionic liquids (RTILs) 1-3
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