Acompanhamento do processo de compostagem da serragem de Pinus taeda pelas características químicas e espectroscópicas das substâncias húmicas em formaçao

Orientador : Antonio Salvio MangrichCo-orientador : Fábio SimonelliTese (doutorado) - Universidade Federal do ParanáResumo: A caracterização química de substâncias húmicas (SH) é uma importante etapa na compreensão do processo de humificação. A despeito de seu papel imprescindível na sustentabilidade da vida, a natureza química e a reatividade das SH são ainda pouco conhecidas. SH são misturas originadas da degradação de restos vegetais, do metabolismocatabolismo microbiano, ou de ambos processos. A compostagem é um processo bioxidativo de tratamento de resíduos orgânicos que, sob condições controladas, pode servir para o estudo químico detalhado do processo de humificação e da formação de SH, propiciando a formação de um húmus menos heterogéneo e a partir de materiais de partida bem caracterizados quimicamente. O objetivo deste trabalho foi estudar as alterações químicas ocorridas no material durante a compostagem da mistura de serragem de Pinns taeda e lodo biológico de fábrica de celulose de Pinns. Este material foi usado para estudar o processo de humificação, através da caracterizaçãoespectroscópica e de cromatografia de exclusão por tamanho das fiações húmicas. Os resultados mostraram que o húmus produzido gerou SH de tamanho molecular entre 800 e 12000 Da, ricos em grupos oxigenados (carboxilas e fenóis), em complexos metálicos de ferro, cobre e manganês e em radicais livres orgânicos. A variação do tamanho dos agregados durante a compostagem s e relacionou a aspectos como aeração e relação O/C. O índice de oxidação das estruturas parece reger estas relações. Em húmus "jovens", a fiação fulvica parece ser especialmente afetada por estas relações. O modelo clássico de descrição das SH como macromoléculas poliméricas não explica os resultados obtidos neste trabalho. Estes resultados parecem concordar com a descrição das SH como associações supramoleculares de moléculas relativamente pequenas, unidas por forças fracas em sistema de "self-assembly", ao invés da descrição destas substâncias como macromoléculas. Forças atrativas hidrófobas e ligações de hidrogénio parecem reger os processos de agregação em soluções diluídas, resultando em agregados de tamanhos moleculares maiores, com o aumento da concentração. A repulsão eletrostática predominante quando um limite crítico de concentração é ultrapassado, faz com que os tamanhos dos agregados moleculares se tornem menores. A interação das SH com espécies anfifílicas tais como ácidos orgânicos, parece atuar especialmente desta forma.Abstract: The chemical characterization of humic substances (HS) is an important step to understand the humification process. Despite their role in the sustainability of life, the basic chemical nature and reactivity of HS are still poorly understood. HS are mixtures developed from plant and animal decays, from microbial metabolism-catabolism, or from both. Composting is a bioxidative process of organic wastes treatment, which could be used, under specified conditions, for H S formation s tudies, s ince i t i s possible t o o btain homogeneous and well chemical well-defined materials. The aim of this work was to study the chemical alterations during the composting of Pinus taeda sawdust and paper mill sludge. The humic fractions obtained from compost were studied by using spectroscopic techniques (EPR, DRIFT, UV-vis and NMR) and sizeexclusion chromatography. The results show that the humus compost formed HS with molecular size between 800 and 12000 Da, rich in oxygenated groups as carboxyl and phenols, in metallic complex as iron, copper and manganese, and in free organic radicals. The molecular size variation of the humic aggregates from compost was correlated with O/C ratio and aeration. In fresh humus, fixlvic fraction seems to be specially affected by this parameters. Such results would have been difficult to explain based on the polymeric description of humic substances. Conversely, our findings can be easily explained on the basis of the supramolecular understanding of humic substances that describes these natural materials as heterogeneous and rather small molecules associated by dispersive forces in supramolecular structures. Hydrophobic forces (%-n, CH-71, van der Waals, charge-transfer bonds) and H-bondings seems to rule the aggregation process in diluted solutions, resulting in greater aggregates with the increase of concentration. Electrostatic repulsion predominates when a critical concentration limit is exceeded and as a result, the molecular size becomes smaller. Humic superaggregates interactions with amphiphilic species as organic acids seems might to have such behavior

Biochar as a sustainable alternative to açaí waste disposal in Amazon, Brazil

© 2020 Institution of Chemical Engineers The açaí palm (Euterpe oleracea Mart) is native to the floodplains of central and South America and is cultivated in Brazil for its berries, which are considered to be a ‘superfood’. The waste açaí fiber and seeds obtained after fruit processing pose a challenge since they remain unutilised despite being an abundant waste by-product of açaí processing.This leads to a build-up of waste, regular dumping and environmental management challenges. Here we examine the potential use of açaí seed biochar as a soil conditioner. The biochar was produced from waste seeds in a handmade kiln, incorporated into two soils of different textures and then compacted in volumetric rings with a hydraulic press. The samples were kept in a greenhouse for a 270-day incubation period. After this, the samples were evaluated for their soil physical and chemical attributes. Nine months after the application of the açaí seed biochar, soil physical properties were not affected, except for the soil aggregate size distribution, for which the highest dosage resulted in a larger weighted average diameter. However, biochar increased phosphorus, potassium and magnesium contents, and reduced the aluminum content, which was reflected in an increase of the base saturation and a reduction in aluminum saturation. Therefore, within a relatively short time period, the biochar was found to improve soil chemical quality more so than soil physical properties, thus offering potential as a sustainable solution to manage açaí waste in the Amazon region

Biochar: pyrogenic carbon for agricultural use: a critical review.

O biocarvão (biomassa carbonizada para uso agrícola) tem sido usado como condicionador do solo em todo o mundo, e essa tecnologia é de especial interesse para o Brasil, uma vez que tanto a ?inspiração?, que veio das Terras Pretas de Índios da Amazônia, como o fato de o Brasil ser o maior produtor mundial de carvão vegetal, com a geração de importante quantidade de resíduos na forma de finos de carvão e diversas biomassas residuais, principalmente da agroindústria, como bagaço de cana, resíduos das indústrias de madeira, papel e celulose, biocombustíveis, lodo de esgoto etc. Na última década, diversos estudos com biocarvão têm sido realizados e atualmente uma vasta literatura e excelentes revisões estão disponíveis. Objetivou-se aqui não fazer uma revisão bibliográfica exaustiva, mas sim uma revisão crítica para apontar alguns destaques na pesquisa sobre biochar. Para isso, foram selecionados alguns temaschave considerados críticos e relevantes e fez-se um ?condensado? da literatura pertinente, mais para orientar as pesquisas e tendências do que um mero olhar para o passad

Molecular and morphological characterization of hydrochar produced by microwave-assisted hydrothermal carbonization of cellulose

The objective of this work was to characterize the morphology and molecular composition of the hydrochar produced by microwave-assisted hydrothermal carbonization of cellulose. The produced hydrochar consists mainly of aggregate microspheres with about 2.0 µm in diameter, with aliphatic and aromatic structures and the presence of carbonyl functional groups. The aromatic groups are formed mainly by benzofuran-like structures, being chemically different from common cellulose char. Microwave-assisted hydrothermal carbonization yields a functionalized carbon-rich material similar to that produced by the conventional hydrothermal process

Context and importance of biochar research

In the context of global warming, major changes are expected in the worldwide energy matrix in the near future. Biomass, a renewable source, as a raw material for energy production, is fundamental in this process. By definition, biochar is any source of biomass previously heated in the absence or at low concentrations of oxygen with the purpose of application to the soil (Maia et al., 2011). The production of biomass for energy (biofuels) requires, above all, soil resources, in terms of occupied land and soil productivity. There are different ways of producing energy from biomass, and the resulting biochar may vary in its physical and chemical composition depending on the kind of biomass and on the conditions of pyrolysis. The technologies that produce biochar as the main product or byproduct of a pyrolysis process are the only ones, among the available biofuel technologies, that may contribute to the improvement or maintenance of soil properties, and, therefore, to the sustainable production of energy and food.In the context of global warming, major changes are expected in the worldwide energy matrix in the near future. Biomass, a renewable source, as a raw material for energy production, is fundamental in this process. By definition, biochar is any source of biomass previously heated in the absence or at low concentrations of oxygen with the purpose of application to the soil (Maia et al., 2011). The production of biomass for energy (biofuels) requires, above all, soil resources, in terms of occupied land and soil productivity. There are different ways of producing energy from biomass, and the resulting biochar may vary in its physical and chemical composition depending on the kind of biomass and on the conditions of pyrolysis. The technologies that produce biochar as the main product or byproduct of a pyrolysis process are the only ones, among the available biofuel technologies, that may contribute to the improvement or maintenance of soil properties, and, therefore, to the sustainable production of energy and food

Biochar na composição de substratos para a produção de mudas de teca

The objective of this work was to evaluate the development and quality of clonal seedlings of teak (Tectona grandis) grown in substrate with two types of biochar. The assay was carried out in a randomized complete block design, with ten treatments and four replicates: CS, commercial substrate, composed of pine bark and vermiculite at a ratio of 4:1; NS, nursery substrate composed of carbonized rice husk and coconut fiber at 1:1; and the remaining treatments were composed of the inclusions of biochar (BC) or activated biochar (BCA) in the CS, at the proportions of 25, 50, 75, and 100%. The development and quality parameters of seedlings were evaluated 90 days after striking the minicuttings in the substrates. BCA substrate additions at 25, 50, and 100% allowed for a development of height and stem diameter comparable to that of the NS. Biochar without the activation procedure does not improve quality parameters of seedlings, in comparison with the commercial substrate. The use of 25% activated biochar added to the commercial substrate is enough to improve seedling growth performance to the same level as that provided by the already validated NS

Hidrofobicidade em Neossolo litólico sob plantação de Pinus taeda

The understanding of soil carbon stabilization processes can be very useful in the development of mitigation techniques for CO2 emissions and global warming. The greater the hydrophobicity of soil organic matter the more stabilized soil organic carbon. Therefore,  hydrophobicity can be a sensitive index to characterizethe ‘quality’ of soil organic matter. In this context, the present work aimed to characterize the chemical  structures of humic acids collected at three different depths in a hydrophobic Entisol (Neossolo) under  loblolly plantation. The results of spectroscopic and chemical analyses (UV-Vis, fluorescence, EPR and X-ray diffractometry) indicated that, as soil depth increased, so did the content of conjugated organic structures, aromatic groups, and free organic radicals, leading to higher humification indices. Aliphatic groups in these fractions were more concentrated in the surface layer than in deeper ones, which can be explained by the constant input of litter. The greater hydrophobicity of the surface soil sample was due to these non-humic components of the organic matter, as suberin and cutin.doi: 10.4336/2010.pfb.30.62.93Compreender os processos de estabilização do carbono no solo pode ser muito útil no desenvolvimento de técnicas de mitigação das  emissões de CO2 e do aquecimento global. Quanto maior a hidrofobicidade da matéria orgânica do solo, mais estabilizado é o carbono do solo. Portanto, a  hidrofobicidade pode ser usada como indicador para  caracterizar a qualidade da matéria orgânica do solo. O presente trabalho caracterizou as estruturas  químicas de ácidos húmicos extraídos de solos  coletados a três profundidades de um Neossolo sob plantação de Pinus taeda. Os resultados das análises  espectroscópicas e químicas (ultra-violeta,  fluorescência, ressonância paramagnética eletrônica e difração de raio-X) indicaram que a ocorrência de  estruturas conjugadas, grupos aromáticos e radicais orgânicos livres e, portanto, maiores índices de  humificação, aumentaram com a profundidade do  solo. Grupos alifáticos na fração húmica estavam  mais concentrados nas camadas superficiais, o que pode ser explicado pelo constante aporte de liteira na superfície. Testes da repelência à água apontarammaior hidrofobicidade na superfície do solo, provavelmente devido a componentes não húmicos da matéria orgânica, tais como suberina e cutina. doi: 10.4336/2010.pfb.30.62.9