Biochar production and use are part of the modern agenda to recycle wastes, and to retain nutrients, pollutants, and heavy metals in the soil and to offset some greenhouse gas emissions. Biochars from wood (eucalyptus sawdust, pine bark), sugarcane bagasse, and substances rich in nutrients (coffee husk, chicken manure) produced at 350, 450 and 750°C were characterized to identify agronomic and environmental benefits, which may enhance soil quality. Biochars derived from wood and sugarcane have greater potential for improving C storage in tropical soils due to a higher aromatic character, high C concentration, low H/C ratio, and FTIR spectra features as compared to nutrient-rich biochars. The high ash content associated with alkaline chemical species such as KHCO3 and CaCO3, verified by XRD analysis, made chicken manure and coffee husk biochars potential liming agents for remediating acidic soils. High Ca and K contents in chicken manure and coffee husk biomass can significantly replace conventional sources of K (mostly imported in Brazil) and Ca, suggesting a high agronomic value for these biochars. High-ash biochars, such as chicken manure and coffee husk, produced at low-temperatures (350 and 450°C) exhibited high CEC values, which can be considered as a potential applicable material to increase nutrient retention in soil. Therefore, the agronomic value of the biochars in this study is predominantly regulated by the nutrient richness of the biomass, but an increase in pyrolysis temperature to 750°C can strongly decrease the adsorptive capacities of chicken manure and coffee husk biochars. A diagram of the agronomic potential and environmental benefits is presented, along with some guidelines to relate biochar properties with potential agronomic and environmental uses. Based on biochar properties, research needs are identified and directions for future trials are delineated.

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The objective of the present study was to evaluate lignocellulosic particles from sub-products of the coffee industry (coffee parchment -CP and husk -CH) into polyhydroxybutyrate (PHB) as a promising reinforcing filler in the biocomposites. The effects of type (CP or CH) and content (neat, 10% and 20%) of coffee wastes on the thermal, mechanical, microstructural and physical properties of the ensuing composites were evaluated. Thermal stability of the composites was improved by the coffee residues at different contents, while degree of crystallinity was decreased with the inclusion of CP. The addition of 10% of CP has not influenced significantly the tensile strength (TS) and Izod strength (IS), in relation to the neat PHB. Tensile strength (TS), MOE and Izod strength (IS) of the composites have increased significantly with the inclusion of 20% of CP. The increase in the content of coffee waste particles increased the water absorption of the composites.

RESUMO -O objetivo deste trabalho foi avaliar a degradação térmica da madeira de diferentes clones de Eucalyptus, por meio de análises termogravimétrica (TG/DTG) e de calorimetria exploratória diferencial (DSC), estabelecendo-se suas relações com a produção de carvão vegetal. Foram utilizados seis clones de Eucalyptus spp. aos 7,5 anos de idade, provenientes de um teste clonal pertencente a uma empresa florestal. Foram realizadas as análises TG/DTG e DSC, sob atmosfera de gás nitrogênio. As curvas TG/DTG mostraram três faixas de degradação térmica, atribuídas à secagem da madeira e à degradação de hemiceluloses e celulose. Não foi detectada faixa específica de degradação de lignina. As curvas DSC evidenciaram um pico endotérmico entre as temperaturas de 50 e 100 ºC, o que pode ser atribuído à perda de água da madeira. A liberação de calor iniciou-se em temperaturas acima de 275 °C, para todos os clones avaliados, sendo observados dois picos exotérmicos. As análises térmicas da madeira (TG/DTG e DSC) não apresentaram variações expressivas entre os clones. Conclui-se que, através das técnicas estudadas, é possível identificar as principais fases das reações de liberação ou absorção de energia e perda de massa, que estão diretamente ligadas à qualidade do carvão vegetal.Palavras-chave: Pirólise; Componentes químicos; Carvão vegetal. STUDY OF THERMAL DEGRADATION OF Eucalyptus WOOD BY THERMOGRAVIMETRY AND CALORIMETRY

O objetivo desse trabalho foi avaliar o efeito do local e do espaçamento de plantio na produção e na qualidade do carvão vegetal de um clone de Eucalyptus urophylla. Amostraram-se cinco discos ao longo do fuste das árvores do clone 3336. As carbonizações foram realizadas em uma mufla com temperatura final de 450 °C. Foram avaliados os rendimentos da carbonização, a análise química imediata, a densidade básica da madeira, a densidade relativa aparente e o poder calorífico superior do carvão vegetal. Utilizou-se um delineamento inteiramente casualizado disposto em um esquema fatorial 2 × 2, considerando-se como níveis dos fatores os diferentes locais (Curvelo e Itacambira) e os espaçamentos de plantio (3 × 3 m e 3 × 4 m). Observou-se dependência entre local e espaçamento apenas para o teor de cinzas. A densidade básica da madeira foi influenciada pelo espaçamento e pelo local. Observou-se influência do local apenas para o teor carbono fixo e os rendimentos gravimétricos em carvão vegetal e carbono fixo. O espaçamento de plantio não afetou significativamente a qualidade e a produção do carvão vegetal avaliado.

The high degree of variability among suppliers and types of biomasses hinders their application in energy production. Investigation into this drawback is needed for the use of the waste produced from açaí depulping, which is widely available throughout the Amazonia. This work aimed to analyze the variability of the yield and physical properties of the açaí waste among different Amazonian producers located at Macapá, AP, Brazil. In addition, energetic attributes of different waste components, namely, seeds and lignocellulosic fibers, were compared to determine if they should be separated prior to burning or pyrolysis. The average yield (71.0%–95.0%), dry basis moisture content (66.6%–76.2%), and basic density (0.753 g cm−3 to 0.812 g cm−3) of açaí waste varied remarkably among the suppliers. Fibers and seeds depicted similar higher heating values (19.91 MJ kg−1 and 19.32 MJ kg−1) and fixed carbon (21.39% and 21.50%) and volatile matter (77.32% and 76.65%), while the ash content was slightly lower for seeds (1.29%–2.08%) in comparison to fibers (1.85%–2.63%). Thermogravimetric analysis revealed different initial degradation temperatures and mass loss rates for the seeds and fibers. It was concluded that the yield and physical properties of açaí waste varied remarkably among providers. A drying process should be carried out before açaí waste burning due to its high moisture content. The high basic density is an advantageous feature of açaí waste in the context of bioenergy. Separation of the components is recommended prior to pyrolysis to avoid heterogeneous charcoal.

The use of biomass has been recognized as a potential renewable energy and an alternative substitute that contributes to the decrease of fossil fuels consumption. Therefore, this research aimed to analyze the thermal behavior of briquettes made of residues from coffee grain processing in different conditions: in natura, torrefied and carbonized. Eucalyptus sawdust was used for comparison. The briquettes were carbonized considering final temperature of 450° C (kept for 30 min). The briquettes torrefaction was performed in an electric oven (muffle) using two heating rates until 250° C (kept 60 min). The thermal-gravimetric analysis was made in nitrogen atmosphere until the temperature of 600° C. The contents of fixed carbon and volatile matter of the fuels were determined. The carbonized briquette of residues from coffee grain processing presented higher stability and low thermal decomposition. It was observed a low influence of torrefaction heating rate under thermal properties of briquettes, and fixed carbon and volatile matter content. Regarding the raw biomass, lower total mass loss was observed for the residues from coffee grain processing when compared to Eucalyptus sawdust. The carbonized and torrefied briquettes presented higher hydrophobicity than raw briquettes.

<p><span>O objetivo deste estudo foi avaliar </span><em><span lang="PT">pellets</span></em><span> torrificados e </span><em><span lang="PT">in natura</span></em><span>,</span><em></em><span>produzidos a partir da madeira residual de </span><em><span lang="PT">Pinus</span></em><span>, destinados ao uso bioenergético. A compactação da madeira residual de </span><em><span lang="PT">Pinu</span></em><span>s sp. oriunda de serraria foi realizada em uma peletizadora </span><span lang="PT">com matriz plana de 8 mm. As torrefações foram realizadas em forno elétrico, tipo mufla, estabilizado em temperaturas finais de 220 °C e 250 °C por 30 min. Foram determinadas as seguintes propriedades nos <em>pellets</em>: densidades aparente e energética unitárias, densidades a granel e energética do granel, composição química imediata (materiais voláteis, cinzas e carbono fixo), poder calorífico superior e umidade. Observou-se aumento do poder calorífico superior e redução do teor de umidade nos <em>pellets</em> torrificados, contudo, o ganho em valor calórico foi inferior à perda de massa dos <em>pellets</em> após a torrefação, reduzindo assim a densidade energética dos <em>pellets</em>. O</span><span>s </span><em><span lang="PT">pellets in natura</span></em><span> apresentam potencial de comercialização em países europeus, como Alemanha, Áustria e Suécia. A metodologia utilizada para torrefação não é indicada para o tratamento térmico de </span><em><span lang="PT">pellets. </span></em><span>Porém, recomendam-se novas pesquisas sobre torrefação de </span><em><span lang="PT">pellets</span></em><span> em uma faixa mais ampla de temperatura e tempo de residência, visando determinar parâmetros que otimizem as propriedade energéticas.</span></p>