Síntese e caracterização de óxidos de grafeno a partir da pirólise de ácido cítrico em atmosfera inerte de nitrogênio
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Data
2022-11-24
Autores
Almeida, Leonardo de Assis
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A pirólise controlada do ácido cítrico é capaz de produzir óxidos de grafeno
na sua estrutura, resultados recentes mostram que o óxido de grafeno ancorado
com materiais capazes de realizar filtragem como a areia é capaz de ampliar a
qualidade da filtragem realizada em recursos hídricos. Os óxidos de grafeno
anexados a essas estruturas têm capacidades adsorventes eficazes para a remoção
de íons de metais pesados, pesticidas e corantes naturais. Estudos recentes
demonstraram que o controle do processo de síntese desses complexos de carbono
a partir da pirólise do ácido cítrico em diversas temperaturas e atmosferas pode
otimizar e/ou potencializar as propriedades de emissão de luz do material, indicando
uma alteração na estrutura. Neste trabalho foram sintetizadas diversas amostras de
óxido de grafeno a partir da pirólise do ácido cítrico a 250 oC/2h, 300 ºC/2h e 400
ºC/2h em atmosfera aberta e 450 ºC/4h, 550 ºC/4h, 750 ºC/3h/4h/6h/8h e 950 ºC/4h
em atmosfera controlada de nitrogênio. A partir de medidas de espectroscopia
Raman foi possível confirmar a presença de óxidos de grafeno a partir da pirólise do
ácido cítrico em atmosfera aberta a partir de 300 ºC/2h, entretanto a amostra de 400
ºC/2h sofreu uma degradação dos óxidos de grafenos formados devido ao início do
processo de combustão em atmosfera aberta. As amostras de síntese em atmosfera
controlada de N2 apresentaram formação de óxidos de grafeno em todas
temperaturas escolhidas, contudo a intensidade das bandas D e G sofreram
alteração. A amostra de 550 ºC/4h N2 teve o pico da banda G aumentado enquanto
a amostra 950 ºC/h N2 mostrou um aumento na Banda D, com isso foi possível
constatar alterações nas composições dos óxidos de grafeno, esses dados
demonstraram que o controle de atmosfera e temperatura altera as ligações sp2
e sp3 no óxido de grafeno.
The controlled pyrolysis of citric acid is capable of producing graphene oxides in its structure, recent results show that graphene oxide anchored with materials capable of filtering such as sand is capable of increasing the quality of filtration performed in water resources. Graphene oxides attached to these structures have effective adsorbent capabilities for the removal of heavy metal ions, pesticides and natural dyes. Recent studies have shown that controlling the synthesis process of these carbon complexes from citric acid pyrolysis at different temperatures and atmospheres can optimize and/or enhance the light emission properties of the material, indicating a change in structure. In this work, several graphene oxide samples were synthesized from citric acid pyrolysis at temperatures of 250 oC/2h, 300 ºC/2h e 400 ºC/2h in an open atmosphere and 450 ºC/4h, 550 ºC/4h, 750 ºC/3h/4h/6h/8h and 950 ºC/4h in a controlled nitrogen atmosphere. From Raman spectroscopy measurements it was possible to confirm the presence of graphene oxides from citric acid pyrolysis in open atmosphere starting at 300 ºC/2h, however the sample of 400 ºC/2h suffered a degradation of the graphene oxides formed due to the beginning of the combustion process in open atmosphere. The N2 controlled atmosphere synthesis samples showed complex formation at all chosen temperatures, however the intensity of the D and G bands changed. The 550 ºC/4h N2 sample had the G band peak increased while the 950 ºC/h N2 sample showed an increase in the D Band, with this it was possible to verify changes in the compositions of graphene oxides, these data demonstrated that the Atmosphere and temperature control change the sp2 and sp3 bonds in graphene oxide.
The controlled pyrolysis of citric acid is capable of producing graphene oxides in its structure, recent results show that graphene oxide anchored with materials capable of filtering such as sand is capable of increasing the quality of filtration performed in water resources. Graphene oxides attached to these structures have effective adsorbent capabilities for the removal of heavy metal ions, pesticides and natural dyes. Recent studies have shown that controlling the synthesis process of these carbon complexes from citric acid pyrolysis at different temperatures and atmospheres can optimize and/or enhance the light emission properties of the material, indicating a change in structure. In this work, several graphene oxide samples were synthesized from citric acid pyrolysis at temperatures of 250 oC/2h, 300 ºC/2h e 400 ºC/2h in an open atmosphere and 450 ºC/4h, 550 ºC/4h, 750 ºC/3h/4h/6h/8h and 950 ºC/4h in a controlled nitrogen atmosphere. From Raman spectroscopy measurements it was possible to confirm the presence of graphene oxides from citric acid pyrolysis in open atmosphere starting at 300 ºC/2h, however the sample of 400 ºC/2h suffered a degradation of the graphene oxides formed due to the beginning of the combustion process in open atmosphere. The N2 controlled atmosphere synthesis samples showed complex formation at all chosen temperatures, however the intensity of the D and G bands changed. The 550 ºC/4h N2 sample had the G band peak increased while the 950 ºC/h N2 sample showed an increase in the D Band, with this it was possible to verify changes in the compositions of graphene oxides, these data demonstrated that the Atmosphere and temperature control change the sp2 and sp3 bonds in graphene oxide.
Descrição
Palavras-chave
Óxido de grafeno, Ácido cítrico, Atmosfera de nitrogênio, Espectroscopia Raman, Graphene oxide, Citric acid, Nitrogen atmosphere, Raman spectroscopy