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Registro Completo |
Biblioteca(s): |
Embrapa Solos. |
Data corrente: |
07/02/2011 |
Data da última atualização: |
29/03/2022 |
Tipo da produção científica: |
Resumo em Anais de Congresso |
Autoria: |
FREITAS, J. C. C.; HONORATO, H. D. A.; NOVOTNY, E. H.; BONAGAMBA, T. J. |
Afiliação: |
Universidade Federal do Espírito Santo; Universidade Federal do Espírito Santo; ETELVINO HENRIQUE NOVOTNY, CNPS; Universidade de São Paulo. |
Título: |
Solid-state 13C NMR studies of activated carbons prepared from biomass using different chemical agents. |
Ano de publicação: |
2010 |
Fonte/Imprenta: |
In: INTERNATIONAL BIOCHAR CONFERENCE, 3., 2010, Rio de Janeiro. Progressing from Terra Preta de Índios to the whole world: anais. Rio de Janeiro: Embrapa, 2010. |
Idioma: |
Inglês |
Conteúdo: |
Activated carbons are largely employed in several chemical and physical processes nowadays, including water treatment, catalysis, gas storage and others [1]. The surface properties of the porous carbons are determinant for most of such applications. Oxygenated functional groups present at the edges of the aromatic lamellae are known to influence decisively the surface chemistry of these materials [2]. In this work, solid-state 13 C nuclear magnetic resonance (NMR) spectroscopy was used for the analysis of a series of activated carbons prepared from a lignocellulosic precursor, using different chemical activating agents. |
Palavras-Chave: |
Activated carbons; NMR. |
Thesaurus Nal: |
biomass. |
Categoria do assunto: |
P Recursos Naturais, Ciências Ambientais e da Terra |
URL: |
https://ainfo.cnptia.embrapa.br/digital/bitstream/item/26458/1/091.pdf
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Marc: |
LEADER 01297nam a2200181 a 4500 001 1875886 005 2022-03-29 008 2010 bl uuuu u00u1 u #d 100 1 $aFREITAS, J. C. C. 245 $aSolid-state 13C NMR studies of activated carbons prepared from biomass using different chemical agents.$h[electronic resource] 260 $aIn: INTERNATIONAL BIOCHAR CONFERENCE, 3., 2010, Rio de Janeiro. Progressing from Terra Preta de Índios to the whole world: anais. Rio de Janeiro: Embrapa$c2010 520 $aActivated carbons are largely employed in several chemical and physical processes nowadays, including water treatment, catalysis, gas storage and others [1]. The surface properties of the porous carbons are determinant for most of such applications. Oxygenated functional groups present at the edges of the aromatic lamellae are known to influence decisively the surface chemistry of these materials [2]. In this work, solid-state 13 C nuclear magnetic resonance (NMR) spectroscopy was used for the analysis of a series of activated carbons prepared from a lignocellulosic precursor, using different chemical activating agents. 650 $abiomass 653 $aActivated carbons 653 $aNMR 700 1 $aHONORATO, H. D. A. 700 1 $aNOVOTNY, E. H. 700 1 $aBONAGAMBA, T. J.
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Embrapa Solos (CNPS) |
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Registro Completo
Biblioteca(s): |
Embrapa Algodão. |
Data corrente: |
14/01/2020 |
Data da última atualização: |
20/01/2020 |
Tipo da produção científica: |
Artigo em Periódico Indexado |
Circulação/Nível: |
A - 1 |
Autoria: |
VASCONCELOS, N. F.; FEITOSA, J. P. A.; ANDRADE, F. K.; MIRANDA, M. A. R.; SASAKI, J. M.; MORAIS, J. P. S.; SILVA, L. M. A. e; CANUTO, K. M.; ROSA, M. de F. |
Afiliação: |
Niédja Fittipaldi Vasconcelos, Universidade Federal do Ceará - UFC/Departamento de Química; Judith Pessoa Andrade Feitosa, Universidade Federal do Ceará - UFC/Departamento de Química; Fábia Karine Andrade, Universidade Federal do Ceará - UFC/Departamento de Engenharia Química; Marcus Aurélio Ribeiro Miranda, Universidade Federal do Ceará - UFC/Departamento de Física; José Marcos Sasaki, Universidade Federal do Ceará - UFC/Departamento de Física; JOAO PAULO SARAIVA MORAIS, CNPA; LORENA MARA ALEXANDRE E SILVA, CNPAT; KIRLEY MARQUES CANUTO, CNPAT; MORSYLEIDE DE FREITAS ROSA, CNPAT. |
Título: |
Chemically modified cellulose nanocrystals as polyanion for preparation of polyelectrolyte complex. |
Ano de publicação: |
2019 |
Fonte/Imprenta: |
Cellulose, v. 26, n. 3, p. 1725-1746, February 2019. |
Idioma: |
Inglês |
Conteúdo: |
Bacterial cellulose nanocrystals (BCNCs) have hydrophilic surfaces due to hydroxyl groups but are water-insoluble. The carboxymethylation improves the solubility of cellulose in polar media through the insertion of carboxymethyl groups. This study aims to evaluate the use of two different alcoholic solvents in the carboxymethylation reaction of BCNCs: ethanol and isopropanol. BCNCs were obtained under two hydrolysis conditions: sulfuric acid (BCNC-S) and combination of sulfuric and hydrochloric acids (BCNC-S/Cl). Two techniques (NMR and titration) were used to determine the degree of substitution (DS) values. Carboxymethylation of BCNC-S/Cl led to high DS compared to BCNC-S and the use of isopropanol promoted an even greater DS. The thermal properties were not affected after the chemical modification. However, functionalization provided an increase in the negative charge density at the surface of nanostructures and a change in the crystal structure (cellulose type Ia for amorphous), making this material a potential polyanion for the synthesis of polyelectrolyte complexes (PECs). The micrographs showed that the nanocrystals became soluble after carboxymethylation. Carboxymethylated bacterial cellulose nanocrystals hydrolyzed through the mixture of inorganic acids and modified using isopropanol (CBCNC-S/Cl-IPA) was a suitable polyanion to produce PECs with chitosan. The PECs produced had particle size ranging from 276 to 588 nm and zeta potential ranging from - 24.3 to + 39.0 mV. MenosBacterial cellulose nanocrystals (BCNCs) have hydrophilic surfaces due to hydroxyl groups but are water-insoluble. The carboxymethylation improves the solubility of cellulose in polar media through the insertion of carboxymethyl groups. This study aims to evaluate the use of two different alcoholic solvents in the carboxymethylation reaction of BCNCs: ethanol and isopropanol. BCNCs were obtained under two hydrolysis conditions: sulfuric acid (BCNC-S) and combination of sulfuric and hydrochloric acids (BCNC-S/Cl). Two techniques (NMR and titration) were used to determine the degree of substitution (DS) values. Carboxymethylation of BCNC-S/Cl led to high DS compared to BCNC-S and the use of isopropanol promoted an even greater DS. The thermal properties were not affected after the chemical modification. However, functionalization provided an increase in the negative charge density at the surface of nanostructures and a change in the crystal structure (cellulose type Ia for amorphous), making this material a potential polyanion for the synthesis of polyelectrolyte complexes (PECs). The micrographs showed that the nanocrystals became soluble after carboxymethylation. Carboxymethylated bacterial cellulose nanocrystals hydrolyzed through the mixture of inorganic acids and modified using isopropanol (CBCNC-S/Cl-IPA) was a suitable polyanion to produce PECs with chitosan. The PECs produced had particle size ranging from 276 to 588 nm and zeta potential ranging from - 24.3 to + 39.0 ... Mostrar Tudo |
Palavras-Chave: |
Carboxymethylation; Polyelectrolytic complexes. |
Thesaurus NAL: |
Chitosan; Hydrolysis; Nanocrystals. |
Categoria do assunto: |
-- |
URL: |
https://ainfo.cnptia.embrapa.br/digital/bitstream/item/208702/1/Chemically-modified-cellulose.pdf
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Marc: |
LEADER 02321naa a2200277 a 4500 001 2118682 005 2020-01-20 008 2019 bl uuuu u00u1 u #d 100 1 $aVASCONCELOS, N. F. 245 $aChemically modified cellulose nanocrystals as polyanion for preparation of polyelectrolyte complex.$h[electronic resource] 260 $c2019 520 $aBacterial cellulose nanocrystals (BCNCs) have hydrophilic surfaces due to hydroxyl groups but are water-insoluble. The carboxymethylation improves the solubility of cellulose in polar media through the insertion of carboxymethyl groups. This study aims to evaluate the use of two different alcoholic solvents in the carboxymethylation reaction of BCNCs: ethanol and isopropanol. BCNCs were obtained under two hydrolysis conditions: sulfuric acid (BCNC-S) and combination of sulfuric and hydrochloric acids (BCNC-S/Cl). Two techniques (NMR and titration) were used to determine the degree of substitution (DS) values. Carboxymethylation of BCNC-S/Cl led to high DS compared to BCNC-S and the use of isopropanol promoted an even greater DS. The thermal properties were not affected after the chemical modification. However, functionalization provided an increase in the negative charge density at the surface of nanostructures and a change in the crystal structure (cellulose type Ia for amorphous), making this material a potential polyanion for the synthesis of polyelectrolyte complexes (PECs). The micrographs showed that the nanocrystals became soluble after carboxymethylation. Carboxymethylated bacterial cellulose nanocrystals hydrolyzed through the mixture of inorganic acids and modified using isopropanol (CBCNC-S/Cl-IPA) was a suitable polyanion to produce PECs with chitosan. The PECs produced had particle size ranging from 276 to 588 nm and zeta potential ranging from - 24.3 to + 39.0 mV. 650 $aChitosan 650 $aHydrolysis 650 $aNanocrystals 653 $aCarboxymethylation 653 $aPolyelectrolytic complexes 700 1 $aFEITOSA, J. P. A. 700 1 $aANDRADE, F. K. 700 1 $aMIRANDA, M. A. R. 700 1 $aSASAKI, J. M. 700 1 $aMORAIS, J. P. S. 700 1 $aSILVA, L. M. A. e 700 1 $aCANUTO, K. M. 700 1 $aROSA, M. de F. 773 $tCellulose$gv. 26, n. 3, p. 1725-1746, February 2019.
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