Similaridade estrutural de substâncias húmicas de carvão hidrotérmico obtido de vinhaça e bagaço de cana-de-açúcar com as das terras pretas de índio da Amazônia
Carregando...
Data
2019-06-26
Autores
Bento, Lucas Raimundo
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
As Terras Pretas de índio (TPI) são solos conhecidos pela fertilidade associada à matéria orgânica recalcitrante e reativa. Tem se tentado reproduzir experimentalmente a natureza química da matéria orgânica da TPI por meio do tratamento térmico da biomassa, sendo o processo de pirólise e o de carbonização hidrotérmica (CHT) os mais empregados. As substâncias húmicas (SH) constituem parte da matéria orgânica do solo e influenciam suas propriedades químicas, físicas e biológicas, e, portanto, sua fertilidade. O objetivo desse estudo foi o de extrair SH das TPI e substâncias do tipo húmicas (STH) de carvão hidrotérmico (CH) produzido com bagaço de cana-de-açúcar e vinhaça, visando sua caracterização e comparação da funcionalidade química. Foi realizada a CHT do bagaço de cana-de-açúcar, da vinhaça e da mistura de bagaço de cana-de-açúcar e vinhaça com e sem adição de ácido fosfórico. As STH foram extraídas dos CH e as SH da TPI e também de uma área adjacente (ADJ) em profundidade. As amostras foram caracterizadas por meio de ressonância magnética nuclear de 13C, reações de hidrólise e metilação térmicas acopladas à cromatografia gasosa e espectrometria de massas (Thermochemolysis GC-MS), termogravimetria, análise composicional, fluorescência molecular e foram submetidas a bioensaios com sementes de milho. A CHT gerou STH caracterizadas pela presença de grupos aromáticos e cadeias alifáticas, sendo que a adição de ácido no meio reacional deixou as STH mais hidrofóbicas, com maior rigidez estrutural causada principalmente pelo conteúdo aromático. As STH podem ser classificadas em 2 tipos: 1-STH composta por frações hidrofílicas (O-Arila e O-Alquila) e hidrofóbicas (C-Arila), na qual possuem um arranjo mais flexível liberando moléculas bioativas; 2-STH compostas por frações mais hidrofóbicas (C-Alquílico) que não apresentaram bioatividade. As SH das TPI apresentaram maior complexidade e hidrofobicidade estrutural quando comparadas com as ADJ. As SH apresentaram características diferentes em função da profundidade do solo, sendo as SH da TPI mais humificadas em superfície, enquanto as da área adjacente em profundidade. As STH do CH de bagaço de cana-de-açúcar foram as que apresentaram maior similaridade com as SH pela presença de compostos fenólicos, na qual influenciaram o crescimento inicial das sementes milho e se diferiram pela maior presença de estruturas polissacarídicas nas SH. As STH mostraram semelhança com a matéria orgânica natural e mostraram bioatividade em sementes de milho, dependendo da matéria-prima utilizada.
Amazonian Dark Earth (ADE) is known for the higher fertility associated with the recalcitrant and reactive organic matter. It has been tried to mimic experimentally the chemical nature of the organic matter from ADE by the thermal treatment of biomass, employing the pyrolytic process and hydrothermal carbonization (HTC). Humic substances (HS) is part of soil organic matter and influences the chemical, physical and biological properties, playing an import role in the soil fertility. The main objective this study was to extract HS from ADE and humic-like substances (HLS) from hydrochar (HC), aiming to access the composition and to compare the chemical functionality. The HTC of sugarcane bagasse, vinasse and the mixture of sugarcane bagasse and vinasse were carried out with and without addition of phosphoric acid in the reaction medium. HLS were extracted from HC and HS from TPI and also from surrounding soil (SR) in depth. The samples were characterized by 13C nuclear magnetic resonance, thermal hydrolysis and methylation reactions coupled to gas chromatography and mass spectrometry (Thermochemolysis GC-MS), thermogravimetry, composition analysis, molecular fluorescence and were submitted to bioassays using maize seeds. The HTC process generated a HLS characterized by the presence of aromatic groups and aliphatic chains, and the addition of phosphoric acid in the medium reaction left the HLS more hydrophobic, with greater structural rigidity mainly by the aromatic content. HLS presented two supramolecular structures: 1-HLS composed by hydrophilic (O-Aryl and O-Alkyl) and hydrophobic (C-Aryl) moieties, which they have a flexible arrangement enabling the release of bioactive molecules; 2-HLS composed by more hydrophobic (Calkyl) moieties that did not showed bioactivity. The HS from ADE showed a greater structural complexity and hydrophobicity than SR. The HS presented different characteristics in depth; HS from ADE seems to be more humified on top layer, while the SR is in depth. The HLS of HC of sugarcane bagasse were the ones that presented the highest similarity to HS by the presence of phenolic compounds, which influenced the initial growth of the maize seeds and were different due to the greater presence of polysaccharide structures in the soil. The HLS generated employing the HTC process showed similarity with natural organic matter and bioactivity in maize seeds, depending on the raw material.
Amazonian Dark Earth (ADE) is known for the higher fertility associated with the recalcitrant and reactive organic matter. It has been tried to mimic experimentally the chemical nature of the organic matter from ADE by the thermal treatment of biomass, employing the pyrolytic process and hydrothermal carbonization (HTC). Humic substances (HS) is part of soil organic matter and influences the chemical, physical and biological properties, playing an import role in the soil fertility. The main objective this study was to extract HS from ADE and humic-like substances (HLS) from hydrochar (HC), aiming to access the composition and to compare the chemical functionality. The HTC of sugarcane bagasse, vinasse and the mixture of sugarcane bagasse and vinasse were carried out with and without addition of phosphoric acid in the reaction medium. HLS were extracted from HC and HS from TPI and also from surrounding soil (SR) in depth. The samples were characterized by 13C nuclear magnetic resonance, thermal hydrolysis and methylation reactions coupled to gas chromatography and mass spectrometry (Thermochemolysis GC-MS), thermogravimetry, composition analysis, molecular fluorescence and were submitted to bioassays using maize seeds. The HTC process generated a HLS characterized by the presence of aromatic groups and aliphatic chains, and the addition of phosphoric acid in the medium reaction left the HLS more hydrophobic, with greater structural rigidity mainly by the aromatic content. HLS presented two supramolecular structures: 1-HLS composed by hydrophilic (O-Aryl and O-Alkyl) and hydrophobic (C-Aryl) moieties, which they have a flexible arrangement enabling the release of bioactive molecules; 2-HLS composed by more hydrophobic (Calkyl) moieties that did not showed bioactivity. The HS from ADE showed a greater structural complexity and hydrophobicity than SR. The HS presented different characteristics in depth; HS from ADE seems to be more humified on top layer, while the SR is in depth. The HLS of HC of sugarcane bagasse were the ones that presented the highest similarity to HS by the presence of phenolic compounds, which influenced the initial growth of the maize seeds and were different due to the greater presence of polysaccharide structures in the soil. The HLS generated employing the HTC process showed similarity with natural organic matter and bioactivity in maize seeds, depending on the raw material.
Descrição
Palavras-chave
Carbonização hidrotérmica, Biocarvão, Substâncias húmicas, Substâncias do tipo húmica, Terra preta de índio, Bioatividade, Hydrothermal carbonization, Biochar, Humic substances, Humic-like substances, Amazonian dark earth, Bioactivity