Volume 11 Issue 4

The Erythrina americana tree has been widely studied for its antioxidant and antimicrobial activity, principally of the seeds. Few studies have focused on the other tree parts. This work evaluated the effect of drying on the proximate chemical composition, IC50, and total phenolic content (TPC) of different parts of the plant from Erythrina americana. Proximate chemical composition showed significant differences between parts of the plant. Tree bark (TB) exhibited higher protein content, crude fiber, and ash. The IC50 value was significantly different in all parts of the plant; the leaves exhibited lower amounts necessary to reach this value. The drying process had a positive influence on the antioxidant activity in all parts of the plant, with mature flowers (MF) and young flowers (YF) samples. These were the samples that required the lowest concentration of all dry samples to reach the IC50 value. The TPC values showed significant differences between fresh and dry samples except for MF, according the ANOVA and Tukey test (P≤0.05). In conclusion, the drying process has potential for retaining the antioxidant activity in YD and MF.

Within the pulp and paper industry, the recycling of whitewater to reduce fresh water consumption and effluent volume leads to an accumulation of dissolved and colloidal substances (DCS) in the papermaking wet-end system. DCS interacts with certain electrolytes and polyelectrolytes to form non-ionic DCS interferents (pitch deposits and depositions), which adversely affect papermaking. Polyethyleneimine (PEI), a fixing agent with a low molecular weight and high cationic charge density, can control the DCS in the wet-end system. The fixation efficiency of DCS simulacra and the wet-end properties were explored under varying Ca2+ and PEI concentrations in pulp. The fixation and retention efficiency of DCS simulacra were improved, the zeta potential of pulp and drainage rate of pulp increased, and the cationic demand of pulp filtrate decreased with increasing PEI dosage. Ca2+ shielded the negatively charged ions on the surface of the fibers and DCS simulacra, influenced the fixation efficiency of PEI to DCS simulacra, and improved the drainage rate of pulp.

Hydroxyl radicals (HO•) and hydrogen radicals (H•) produced from sub/supercritical ethanol have an obvious contribution on cellulose liquefaction for bio-oil production. Salicylic acid was employed as the HO• trap and CCl4 was employed as the H• trap to investigate the role of HO• and H• on the formation pathways of dominant chemical components in bio-oil during cellulose liquefaction in sub/supercritical ethanol (mostly ketones and esters). The yield of bio-oil decreased from 24.7% to 20.7% with the addition of CCl4, while the bio-oil yield increased from 29.3% to 47.9% with the addition of salicylic acid. Gas chromatography/mass spectrometry results showed that the yields of ketones, esters, and phenols in the bio-oil were 22.3%, 8.8%, and 4.7%, respectively, without salicylic acid or CCl4. The highest yields of esters and phenols increased to 21.6% and 36.9%, respectively, in the presence of salicylic acid. The yield of ketones decreased to 14.1%. Experimental data indicated that the cleavage of C-O-C and C-C bonds in the cornstalk cellulose initially generated many active cellulose fragments. Then, platform chemicals were formed from these fragments through aromatization, isomerization, aldol condensation, Baeyer-Villiger oxidation, and trans-Diels-Alder ring-opening with the redox of HO• and H•.

Electropolymerization was carried out in order to obtain a bio-based polymer by a simple procedure. Ferulic acid, a component of gramineous plants, was selected for this purpose. A thin polymer film was produced in an organic solvent medium (i.e., CH2Cl2/methanol (4:1 v/v) in the presence of 0.2 M LiClO4), whereas it was not obtained in a totally aqueous medium (0.2 M NaOH). Scanning electron microscopic analysis showed that the polymer film had a porous lamellar structure of ~10 μm thickness. Most of the carboxyl groups remained, and IR spectroscopy and time-of-flight secondary ion mass spectrometry (TOF-SIMS) analyses revealed that o-quinones existed in the polymer film. After electropolymerization, caffeic acid, sinapic acid, 3,6-bis(4-hydroxy-3-methoxyphenyl)tetrahydrofuro[3,4-c]furan-1,4-dione (1), and 4,4’-dihydroxy-3,3’-dimethoxy-β,β’-bicinnamic acid (2) were detected in the organic reaction medium; this suggested that demethylation, methoxyl group addition, and radical coupling reactions occurred at the electrode surface.

Agglomerated torrefied wood fuel was tested for its fuel properties and combustion characteristics. Torrefied wood was produced in a wood roaster, with three species (Pinus densiflora Siebold & Zucc., Quercus serrata Thumb. Ex Murray, Sinoarundinaria nigra var. henonis honda) that were torrefied at 220 °C for 180 s. After being torrefied, these powders were used as agglomerated torrefied wood-powder. Gelatin was used as binder, and linseed oil was spread on one side of each sample. All test samples were ignited and tested for carbon monoxide release and temperature variation. The agglomerated torrefied wood fuel showed 82% less carbon monoxide release in comparison to self-igniting briquettes. In particular, pine showed less CO release and mass loss. Also, pine and bamboo showed higher heat efficiency than the ignition coal. Therefore, using torrefied wood for agglomerated fuel reduced the carbon monoxide release and improved the heating efficiency of the ignition coal.

Harnessing energy from biomass is environmentally friendly because of the essentially zero net CO2 impact. As a common agricultural byproduct, corncobs are abundant in quantity. This study was carried out to examine the thermo-physical properties of corncobs and characterize the properties of corncob ash produced from gasification, in order to provide a basis for transforming it into value-added products. The results showed that the pyrolysis of corncobs followed a three-step, stepwise mechanism. Activation energies calculated by the Coats-Redfern method at heating rates of 5, 10, and 20 °C/min were 79.08, 76.73, and 75.78 kJ·mol-1, respectively, implying that the corncobs could be decomposed easily at high heating rates. The emissions of CO, CO2, CH4, H2, H2O, and O2 during pyrolysis corresponded well with thermal curves. Corncob ash could be a good fertilizer because of its high contents of K, P, and Ca. The high SiO2 content makes the corncob ash suitable for ceramics and blended cement concrete. Sylvite (KCl) and quartz (SiO2) were the two major crystal phases in the corncob ash. Relatively large particles of unburnt carbon residues in the ash indicated that low-cost adsorbent could be developed from these carbon residues.

This work evaluated the impact of brownstock pulp kappa number variations on modified pulping process, oxygen delignification, bleaching, and the physical characteristics on bleached pulp. Wood chips of 6-year-old Eucalyptus grandis x Eucalyptus urophylla from Brazil were used. A modified pulping process was performed with the purpose of achieving two delignification levels on brownstock pulp: kappa 18 and kappa 15. Pulps were submitted to oxygen delignification and elemental chlorine-free (ECF) bleaching to achieve 89.5 ± 0.5% of ISO brightness. Subsequently, pulps were refined in four levels (0, 750, 1500, and 3000 rotations) for physical mechanical tests. Delignification increased after increasing the cooking H factor and alkali charge. As a result, delignification negatively impacted the pulping yields (from 56.1% to 55.0%) and the pulp viscosity (from 1,317 cm³/g to 1,227 cm³/g). Pulps with an initial kappa of 15 presented more efficient oxygen delignification and lower consumption of bleaching reagents. The final viscosity of these pulps were lower (899 cm³/g against 963 cm³/g), however, than that of the pulps with an initial kappa of 18. Furthermore, the pulps with a higher unbleached kappa demanded less refining energy and had lower capillarity. The other physical properties were not influenced by the brownstock delignification level.

In the development of integrated biorefinery process alternatives to produce value-added by-products, various black liquors from sulfur-free pulping processes offer potential feedstocks for recovering their main chemical constituents, lignin and aliphatic carboxylic acids. In this study, lignin fractions were obtained from silver birch (Betula pendula) soda-anthraquinone black liquor by carbonation (pH to about 8.5) or by acidification (pH to about 2) with H2SO4 after carbonation or directly. These fractions were characterized by Fourier transform infrared (FTIR), ultraviolet (UV), energy dispersive X-ray fluorescence (ED XRF), and 13C nuclear magnetic resonance (13C NMR) spectroscopy. In addition, the molecular weight distributions of these lignin fractions were determined. All the experimental data clearly suggested that only small differences between the precipitated lignins existed, and thus, their equal chemical utilization seems possible.