Francides Gomes da Silva Júnior

Potential of eleven Eucalyptus species for the production of essential oils

Most Eucalyptus plantations in Brazil aim the production of paper and charcoal, but the use of the species for lumbering, construction and extraction of essential oil has increased. Eleven species of Eucalyptus were assessed in regard to their essential oil production potential, nine never used before for commercial, essential oil extraction. Assessements were compared with Eucalyptus citriodora and Eucalyptus globulus, already explored in oil production for perfume and medical purposes, aiming to increase the availability of commercial species and the relationship between oil production and climatic conditions. Eucalyptus leaves were seasonally sampled (three months interval) for distillation and determination of productivity and chemical composition of oil - contents of oils main components. Eucalyptus viminalis showed the highest potential for cineol, and standed out among the species not yet used commercially. Influenced by soil moisture contents and air temperature, the lowest and the highest oil production happened respectively in Spring and Summer. Water deficiency in Spring caused the lowest oil production. In the Summer, on the other hand, the highest oil production was observed when temperatures were higher and no water deficiency registered. There was no climatic influence on the main oil chemical component.

Application of xylanases from Amazon Forest fungal species in bleaching of eucalyptus kraft pulps

Crude xylanase preparations from Penicillium corylophilum, Aspergillus niger and Trichoderma longibrachiatum were used to treat Eucalyptus kraft pulp, prior to chlorine dioxide and alkaline bleaching sequences. The enzyme pretreatment improved brightness and delignification of non-delignified and oxygen-bleached samples of eucalyptus kraft pulp. Xylanase preparations from T. longibrachiatum and P. corylophilum were more effective to reduce pulp kappa number. A small reduction in viscosity was obtained when the oxygen-bleached pulp was treated with xylanase preparation from A. niger. For all enzyme samples, the best release of chromophoric material from the pulp was at 237 nm. The enzyme preparation from P. corylophilum was responsible for the highest release of reducing sugar at a dosage interval of 10-20 IU/g dry weight pulp. Scanning electron microscopy studies of oxygen-bleached pulp after xylanase treatment revealed morphological changes, including holes, cracks, filament forming and peeling.

Effect of thermal treatment on the chemical characteristics of wood from Eucalyptus grandis W. Hill ex Maiden under different atmospheric conditions

Thermal treatment (thermal rectification) is a process in which technological properties of wood are modified using thermal energy, the result of which is often value-added wood. Thermally treated wood takes on similar color shades to tropical woods and offers considerable resistance to destructive microorganisms and climate action, in addition to having high dimensional stability and low hygroscopicity. Wood samples of Eucalyptus grandis were subjected to various thermal treatments, as performed in presence (140oC; 160oC; 180oC) or in absence of oxygen (160oC; 180oC; 200oC) inside a thermal treatment chamber, and then studied as to their chemical characteristics. Increasing the maximum treatment temperatures led to a reduction in the holocellulose content of samples as a result of the degradation and volatilization of hemicelluloses, also leading to an increase in the relative lignin content. Except for glucose, all monosaccharide levels were found to decrease in samples after the thermal treatment at a maximum temperature of 200oC. The thermal treatment above 160oC led to increased levels of total extractives in the wood samples, probably ascribed to the emergence of low molecular weight substances as a result of thermal degradation. Overall, it was not possible to clearly determine the effect of presence or absence of oxygen in the air during thermal treatment on the chemical characteristics of the relevant wood samples.

Relationship among extractives, lignin and holocellulose contents with performance index of seven wood species used for bows of string instruments

In this paper we investigate the influence of extractives, lignin and holocellulose contents on performance index (PI) of seven woods used or tested for violin bows. Woods with higher values of this index (PI = √MOE/ρ, where MOE is modulus of elasticity and ρ is density) have a higher bending stiffness at a given mass, which can be related to bow wood quality. Extractive content was negatively correlated with PI in Caesalpinia echinata, Handroanthus sp. and Astronium lecointei. In C. echinata holocellulose was positively correlated with PI. These results need to be further explored with more samples and by testing additional wood properties. Although the chemical constituents could provide an indication of quality, it is not possible to establish appropriate woods for bows solely by examining their chemical constituents.

Timber wastes torrefaction for energy use

The experiment consists in the realization of timber wastes torrefaction at a final temperature of 280 oC, with heating rates of 0,5 oC.min-1, with 1 hour permanence in the final temperature. Three different types of wastes were analyzed by composition. Moisture content, bulk density, torrefied mass yield, gross calorific value, particle size, and physical and mechanical resistance were determined. Except the moisture content, the remaining variables were evaluated before and after torrefaction. The results indicated that torrefaction increased the wastes energy density . The torrefied material yield was influenced by the particle size. Bulk density was reduced; however, the mass reduction was higher than the volume reduction. The calorific value was increased for all types of torrefied wastes. Torrefied wastes friability was higher compared to in natura wastes.

The effects of temperature, alkali charge and additives in the oxygen delignification in high kappa number eucalyptus pulp kraft

The purpose of this paper was to evaluate the effect of temperature, alkali charge, anthraquinone and ethanol additives in oxygen delignification for kraft pulp of Eucalyptus grandis vs. Eucalyptus urophylla with high kappa number and rejects content. In pulp production, the conventional kraft cooking was used with 13% alkaline charge, 25% sulfidity, in addition to H factor of 580. To reduce the rejects content, the pulp was subjected to two passages through the disc refiner. The oxygen delignification occurred in medium consistency (10%) and oxygen pressure of 5 kgf·cm-2, in addition to the delignification with the combination of four alkaline charges (15, 30, 45 and 60 kg·t-1) and four temperatures (80, 100, 120 and 140oC). The additives effect evaluation was made with 0.05% of anthraquinone and ethanol separately, just like the treatments with no additives as a reference. The brown pulp kappa number produced was 63.9 with 8.7% of rejects content. The comparison between the alkaline charge and temperature factors shows that the first is more influential in the oxygen delignification process. However, by increasing the temperature it was possible to reduce the kappa number with lower drop in selectivity. In addition, the temperature is the activating agent of the process reactions, given that for any alkaline charge applied, the residual alkali concentration decreases with the temperature increase. Also, there was no great drop in yield with the increased alkali charge and temperature. Simultaneously, the conversion of rejects into pulp ensured the yield maintenance. The anthraquinone addition showed no gains in the yield and in the kappa number results, but the process became more selective. The addition of ethanol showed positive results in terms of kappa number and rejects reduction, and also an increased yield. The total of solids generated had no significant influence of additives action.

Growth ring width of Pinus caribaea var. hondurensis and its relationship with wood proprieties

A striking feature of the genus Pinus are its growth rings, which originate from the seasonal activity of vascular change resulting in successive depositions on the stem. The technological properties of pine wood present variations related to the width of the growth rings, which is a conditioning factor in the physicalmechanical wood performance. The wood of Pinus caribaea var. hondurensis used in this research came from a 20 year old plantation in the region of Catalão GO. Thirty-five specimens divided into three groups according to the width of the growth rings were analyzed: Group 1 (0.0 to 0.7 cm higher percentage of late wood, fine and narrow rings); Group 2 (0.7 to 1.2 cm the percentage of early and late wood is similar rings of medium width); Group 3 (1.2 to 2.0 cm higher percentage of early wood). The basic density, shrinking ability, modulus of elasticity and modulus of rupture were analyzed in static flexion tests, and dynamic elastic moduli determined by stress wave and ultrasound methods. The results indicate that Pinus caribaea var. hondurensis wood with narrower growth rings (greater percentage of late wood, corresponding to group 1) have higher values of density, shrinking ability and also higher stiffness. In this group, the correlations between the properties are higher. In general, the modulus of dynamic elasticity determined by stress wave showed a better correlation with the studied properties than that determined by ultrasound.

Potential use of Libidibia ferrea and Poincianella pluviosa woods for bows of string instruments

To determine the potential for use in the manufacture of string instrument bows, the anatomical features, as well as physical, acoustic and chemical properties, of Libidibia ferrea (pau ferro) and Poincianella pluviosa (sibipiruna) wood were compared against those found in Caesalpinia echinata (pau brasil) wood, the established species for modern bow-making. Recent studies recommend relevant parameters of bow quality, such as wood anatomy, physical and mechanical properties. Based on its similarity to C. echinata in terms of ray width, fiber length, specific gravity and performance index (bending stiffness for a bow of given mass and geometry), P. pluviosa presents higher potential for bow-making than L. ferrea. However, P. pluviosa trees grow in plantations with tight spacing, resulting in higher wood density when compared with trees from natural populations. Heartwood color of L. ferrea is closer to the reddish–brown heartwood of C. echinata, thus differing from P. pluviosa. As such, heartwood similarity could be a positive factor for its acceptance by musicians, who are accustomed to bows made with C. echinata wood. However, based on the initial analysis, L. ferrea may show lower workability by its hardness, making it difficult to manufacture bows. Extractive content did not differ between L. ferrea and P. pluviosa and was lower than that of C. echinata. Lignin was higher in C. echinata and lower in P. pluviosa. Holocellulose was higher in P. pluviosa and lower in C. echinata. Overall, preliminary analyses indicate that both woods have sufficient potential to produce bows adequate to the needs of beginners and amateur musicians.