Evaluation of morphological and chemical aspects of different wood species by spectroscopy and thermal methods

Structural and thermal analysis of a hyper-branched exopolysaccharide produced by submerged fermentation of mushroom mycelium

An exopolysaccharide (PTR-EPS1) purified from the culture medium of the mycelial fermentation of Pleurotus tuber-regium had a weight-average molecular mass of 173.6 kDa and a radius of 55.6 nm.

Contribution of acetic acid to the hydrolysis of lignocellulosic biomass under abiotic conditions

Acetic acid was used in abiotic experiments to adjust the solution pH and investigate its influence on the chemical hydrolysis of the Organic Fraction of Municipal Solid Waste (OFMSW). Soluble chemical oxygen demand (SCOD) was used to measure the hydrolysis under oxidative conditions (positive oxidation-reduction potential values), and pH 4 allowed for 20% (±2%) of the COD added to be solubilized, whereas only 12% (±1%) was solubilized at pH7. Under reducing conditions (negative oxidation-reduction potential values) and pH 4, 32.3% (±3%) of the OFMSW was solubilized which shows that acidogenesis at pH 4 during the anaerobic digestion of solid waste can result in chemical hydrolysis. In comparison, bacterial hydrolysis resulted in 54% (±6%) solubilization.

Native Cellulose: Structure, Characterization and Thermal Properties

In this work, the relationship between cellulose crystallinity, the influence of extractive content on lignocellulosic fiber degradation, the correlation between chemical composition and the physical properties of ten types of natural fibers were investigated by FTIR spectroscopy, X-ray diffraction and thermogravimetry techniques. The results showed that higher extractive contents associated with lower crystallinity and lower cellulose crystallite size can accelerate the degradation process and reduce the thermal stability of the lignocellulosic fibers studied. On the other hand, the thermal decomposition of natural fibers is shifted to higher temperatures with increasing the cellulose crystallinity and crystallite size. These results indicated that the cellulose crystallite size affects the thermal degradation temperature of natural fibers. This study showed that through the methods used, previous information about the structure and properties of lignocellulosic fibers can be obtained before use in composite formulations.

Thermal decomposition of wood: kinetics and degradation mechanisms

The influence of wood components and cellulose crystallinity on the kinetic degradation of different wood species has been investigated using thermogravimetry. Four wood species were studied: Pinus elliottii (PIE), Eucalyptus grandis (EUG), Mezilaurus itauba (ITA) and Dipteryx odorata (DIP). Thermogravimetric results showed that higher extractive contents in the wood accelerate the degradation process and promote an increase in the conversion values at low temperatures. Alternatively, the results indicated that the cellulose crystallinity inhibits wood degradation; organized cellulose regions slow the degradation process because the well-packed cellulose chains impede heat diffusion, which improves the wood's thermal stability. The wood degradation mechanism occurs by diffusion processes when the conversion values are below 0.4. When the conversion values are above 0.5, the degradation is a result of random nucleation with one nucleus in each particle.

Wood chemistry and density: an analog for response to the change of carbon sequestration in mangroves

This study aimed to resolve the variations of physical and chemical properties of wood records measured in different mangroves with their annual carbon sequestration. The methods of investigation used were to examine growth rate by monitoring breast height diameter, wood chemistry and density, FTIR spectroscopy and thermogravimetry. Carbon sequestration rate showing an increase with density varied between 0.088 and 0.171 μg C kg(-1) AGB s(-1), and Avicennia marina showed the maximum value and Bruguiera gymnorrhiza, the minimum. The changes in FTIR bands at 4000-2500 cm(-1) and 1700-800 cm(-1) were correlated to the variations in cellulose in mangrove woods and lignin to cellulose ratio ranged between 0.21 and 1.75. Thermal analyses of mangrove wood suggested that the fuel value index (985-3922) exhibited an increase with the decrease in maximum decomposition temperature and density. The seasonal variation of temperature and CO2 were likely to affect chemical properties through changes in wood density.

Mechanism of interactions between calcium and viscous polysaccharide from the seeds of Plantago asiatica L

The present study aimed at investigating the mechanism of interactions between calcium and the psyllium polysaccharide. Plantago asiatica L. crude polysaccharide (PLCP) was subjected to ethylenediaminetetraacetic acid (EDTA) to yield calcium-depleted polysaccharide named PLCP-E. There was essentially no difference in the structure between PLCP-E and PLCP. However, PLCP-E exhibited a much lower apparent viscosity compared to that of PLCP. PLCP was treated with sodium hydroxide to deplete ferulic acid. The resultant material was named PLCP-FAS, which also exhibited lower viscosity. Adding Ca(2+) could both increase apparent viscosity of PLCP-E and PLCP-FAS, but only PLCP-E could keep the high viscosity when dialysis was carried out to remove free Ca(2+) in the solution. Thermal analysis showed that the thermal stability of the polysaccharide was reduced after EDTA chelation. Scanning electron microscopy (SEM) analysis showed that PLCP-E was flaky and curly aggregation, while PLCP was mostly filamentous in appearance. The results suggested that there are strong interactions between Ca(2+) and the polysaccharide. The interactions contributed to the high viscosity, weak gelling property, and thermal stability of the polysaccharide.

Thermal decomposition of wood: influence of wood components and cellulose crystallite size

The influence of wood components and cellulose crystallinity on the thermal degradation behavior of different wood species has been investigated using thermogravimetry, chemical analysis and X-ray diffraction. Four wood samples, Pinus elliottii (PIE), Eucalyptus grandis (EUG), Mezilaurus itauba (ITA) and Dipteryx odorata (DIP) were used in this study. The results showed that higher extractives contents associated with lower crystallinity and lower cellulose crystallite size can accelerate the degradation process and reduce the wood thermal stability. On the other hand, the thermal decomposition of wood shifted to higher temperatures with increasing wood cellulose crystallinity and crystallite size. These results indicated that the cellulose crystallite size affects the thermal degradation temperature of wood species.