Mario Guimarães Junior

Canonical correlations between chemical and energetic characteristics of lignocellulosic wastes.

Canonical correlation analysis is a statistical multivariate procedure that allows analyzing linear correlation that may exist between two groups or sets of variables (X and Y). This paper aimed to provide canonical correlation analysis between a group comprised of lignin and total extractives contents and higher heating value (HHV) with a group of elemental components (carbon, hydrogen, nitrogen and sulfur) for lignocellulosic wastes. The following wastes were used: eucalyptus shavings; pine shavings; red cedar shavings; sugar cane bagasse; residual bamboo cellulose pulp; coffee husk and parchment; maize harvesting wastes; and rice husk. Only the first canonical function was significant, but it presented a low canonical R². High carbon, hydrogen and sulfur contents and low nitrogen contents seem to be related to high total extractives contents of the lignocellulosic wastes. The preliminary results found in this paper indicate that the canonical correlations were not efficient to explain the correlations between the chemical elemental components and lignin contents and higher heating values.

Thermal decomposition of torrefied and carbonized briquettes of residues from coffee grain processing

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.

Impact of nanofibrillation degree of eucalyptus and Amazonian hardwood sawdust on physical properties of cellulose nanofibril films

The production of cellulose nanofibrils (CNFs) from Amazonian wood wastes could reduce pollution and raw material costs for cellulose industry. Further studies are required to analyze the feasibility of using hardwood sawdust for the production of high-quality CNF films. Therefore, the objective of this study was to evaluate the impact of various nanofibrillation degrees of waste sawdust generated from the primary processing of different hardwood species on the physical properties of CNF films. Raw sawdust was submitted to alkaline and bleaching pre-treatments. The chemical composition of the bleached fibers was determined. The CNFs were obtained by mechanical shearing of the bleached fibers using a grinder Super MassColloider after 10, 20, 30 and 40 passages. CNFs were evaluated by transmission electron microscopy. The CNF films were formed by the casting method. Residual lignin and hemicelluloses content greatly varied among species after bleaching. No clear influence of the number of passages on apparent density was observed. None of the films was degraded in significant amounts after water immersion. Water vapor absorption (WVA) consistently decreased with more passages through the Super MassColloider for Amazonian species until 30 passages. Residual hemicelluloses of the bleached fibers adversely affected WVA. Bleached fibers made of highly purified cellulose or containing residual lignin showed lower WVA after 30 and 40 passages. Water vapor permeability showed consistent relation with the apparent density of the films. For hardwood wastes, 10–30 passages through the grinder are recommended.

Nanocellulose Films from Amazon Forest Wood Wastes: Structural and Thermal Properties

The aim of this work was to determine the best fibrillation intensity that should be used to produce high crystalline and thermal stable microfibrillated cellulose (MFC) and nanocellulose films from C. goeldiana veneer wastes. The number of passages (cycles) of cellulose suspension tested in grinder were 10, 20, 30 and 40. Important properties to be analyzed included changes in morphology from the raw wood to the nanocellulose films, increases/decreases in cellulose crystalline index for inference on biomaterial strength, and thermal behavior changes to support conclusions on biomaterials processing and application possibilities. After chemical treatments for cellulose isolation, mechanical shearing was applied to produce cellulose nanostructures; hence nanocellulose films could be successfully produced from C. goeldiana wood wastes. Influence of more refining cycles on thermal properties, indicated higher stability for 40-cycles nanocellulose films. In general, grinder refining process decreased crystalline index of cellulose.

COMBUSTION OF BIOMASS AND CHARCOAL MADE FROM BABASSU NUTSHELL

RESUMO: Nos ultimos anos, pesquisadores tem analisado o uso de residuos lignocelulosicos para geracao de energia. No entanto, ha uma falta de informacao sobre a combustibilidade da biomassa residual, especialmente a casca e o carvao vegetal do coco babacu. Neste estudo foram utilizadas as analises termogravimetricas (TGA), termica diferencial (DTA) e de calorimetria exploratoria diferencial (DSC) para: avaliar a combustao da biomassa residual do coco babacu; avaliar a combustao do carvao vegetal produzido a partir dessa biomassa, considerando diferentes temperaturas finais de carbonizacao; e verificar o efeito da temperatura final de carbonizacao na estabilidade termica do carvao vegetal e no seu desempenho na combustao. As analises termicas foram realizadas em atmosfera de ar sintetico. Para avaliar as caracteristicas da combustao do carvao vegetal e da biomassa in natura foi considerada a temperatura de ignicao (Ti), a temperatura final da combustao (Tf), o indice caracteristico da combustao (S), o indice de ignicao (Di), o tempo correspondente a maxima taxa de combustao (tp) e o tempo de ignicao (tig). A combustao da casca do coco babacu ocorreu em tres fases distintas e observou-se que esse material lignocelulosico apresenta aptidao para a producao direta de calor. O aumento da temperatura final de carbonizacao causou um aumento da temperatura de ignicao, da temperatura final da combustao, do tempo de ignicao e do tempo correspondente a maxima taxa de combustao. Os resultados indicam que o aumento da temperatura de carbonizacao causa uma diminuicao da intensidade da combustao e, consequentemente, os carvoes produzidos em temperaturas mais baixas sao mais faceis de inflamar e apresentam melhor desempenho na ignicao.

Técnicas multivariadas aplicadas à avaliação de resíduos lignocelulósicos para a produção de bioenergia

The evaluation of lignocellulosic wastes for bioenergy production demands to consider several characteristics and properties that may be correlated. This fac...

Effect of the nano-fibrillation of bamboo pulp on the thermal, structural, mechanical and physical properties of nanocomposites based on starch/poly(vinyl alcohol) blend

The current work aimed to evaluate the influence of adding bamboo cellulose nanofibrils on the performance of poly(vinyl alcohol)—PVA and modified cassava starch—FMM blend nanocomposites. Nanofibrils were produced after 5 and 30 passes through the mechanical defibrillator. Blends formed from PVA and FMM in an 80/20 ratio were used for casting preparation of the nanocomposites reinforced with 6.5% of nanofibrils. Atomic force microscopy showed the deconstruction of the fiber wall with release of the cellulose nanofibrils. A higher degree of nano-fibrillation occurred after 30 passes. The interaction between the polymers and the reinforcement after 30 passes was verified by Fourier transform infrared spectroscopy and scanning electronic microscopy. The higher nano-fibrillation promoted higher homogeneity, cohesion and more compact structure, thus promoting the formation of larger well-defined crystals, which acted as nucleating agents in the matrix, as demonstrated by differential scanning calorimetry and X-ray diffractrometry. It led to improvements of the physical, thermal and mechanical properties of the nanocomposites, conferring them great potential for applications in the plastic film industries.

STRENGTH IMPROVEMENT OF HYDROXYPROPYL METHYLCELLULOSE/ STARCH FILMS USING CELLULOSE NANOCRYSTALS

O interesse em nanocristais de celulose obtidos a partir de recursos naturais tem crescido principalmente devido a caracteristicas que esses materiais fornecem quando inseridos em matrizes polimericas. O presente estudo teve como objetivo avaliar o efeito da adicao de nanocristais de celulose nas propriedades mecânicas dos biofilmes feitos a partir de hipromelose (ou hidroxipropil metilcelulose - HPMC) e misturas com amido de mandioca (CS). Os nanocristais de celulose foram produzidos por hidrolise acida e caracterizados por microscopia optica (OM), microscopia eletronica de transmissao (TEM), difracao de raios X (XRD) e termogravimetria (TG). Os filmes foram feitos por fundicao (ou “casting”) com CS puro, hipromelose pura e tambem com misturas de CS e hipromelose. Em seguida, os nanocristais de celulose foram adicionados as misturas nas concentracoes de 1, 3 e 10% (m/m). As avaliacoes dos filmes incluiram a resistencia a tracao e a superficie da fratura por microscopia eletronica de varredura (SEM). Observou-se que o reforco com nanocristais de celulose melhorou as propriedades mecânicas, e as observacoes da superficie de fratura dos filmes testados mostraram que os nanocristais promoveram uma melhora na coesao da hipromelose e do amido na mistura e promoveram uma superficie mais homogenea.