Abstract: Correct identification of species in wood and charcoal commerce is important, and rapid and nondestructive evaluation based on near-infrared techniques can be a good alternative. Four trees from Combretum leprosum, Croton argyrophylloides, Jatropha mutabilis, Luetzelburgia auriculata, Mimosa tenuiflora and Poincianella bracteosa, were cut in a natural forest in the municipality of Coremas, Paraíba state and stem discs with thickness of about 80 mm were taken at 0, 25, 50, 75 and 100% of commercial height. For charcoal production, each sample was wrapped in aluminum foil and carbonized in a muffle furnace, with a final temperature of 450 °C and a heating rate of 1,66 °C min-1. Spectra were collected directly from sample surface. The best pretreatment was second derivative, while the best classification method was PCA-LDA, and the analysis of full spectra (4000-10000 cm-1) was indicated. In classification, there was no difference between surfaces where spectra was collected, so in practice, in commercial control for example, the information can be obtained from any surface. For rapid analysis for purposes of control of forest practices or illegal commerce, spectra collected directly from wood and charcoal can be applied to distinguish these six Caatinga species.

Samples of wood sold as "angelim" in Brazil were studied. Disks from the trunks of Diplotropis purpurea, Hymenolobium petraeum, Parkia pendula, Vatairea guianensis and Vatairea paraensis were obtained from Mato Grosso state. Samples from pith to bark of each species were obtained, oriented in the three anatomical planes. Each sample was wrapped in aluminum foil and carbonized in a muffle furnace, with a final temperature of 450 °C and a heating rate of 1,66 °C min-1. The description of the anatomical elements of wood and charcoal samples followed the orientations of the International Association of Wood Anatomists, on the basis of 25 readings regarding frequency and tangential diameter of the vessels and height and width of the rays in micrometers. Infrared analyses were performed with a Bruker Tensor 37 spectrophotometer equipped with an integrating sphere and operating in reflectance mode, with resolution of 4 cm-1 and a spectral range of 10000-4000 cm-1. The wood and charcoal samples were placed on top of integrating sphere and one spectrum was obtained from each surface, resulting in six spectra for each physical sample. The results of anatomical analysis showed that the qualitative characteristics of wood remained in charcoal, so the method can be applied for species discrimination. When comparing cell dimensions, we observed different behavior between species in the same carbonization process in function of cell wall thickness and parenchyma distribution. In infrared analysis, pretreatment influenced adequate discrimination of "angelim" species in wood and charcoal. Linear discriminant analysis based on PCA scores and the region between 4000-6200 cm-1 was more efficient. Near infrared analysis can be used for differentiation of wood and charcoal of "angelim" species.

O carvão vegetal é um importante insumo energético, sendo suas propriedades influenciadas pela composição anatômica e química da madeira utilizada e pelo processo de produção. Esse trabalho teve como objetivo avaliar as características anatômicas, poder calorífico e o conteúdo de voláteis e cinzas da madeira carbonizada de Byrsonima spicata, Calophyllum brasiliense, Cecropia sciadophylla, Cochlospermum orinocense e Schefflera morototoni. O poder calorífico variou de 26.878 a 31.117 kJ kg-1; o teor de voláteis variou de 20,9 a 31,76%; o teor de cinzas variou de 0,1 a 3,8% e o teor de carbono no carvão ficou entre 68,2 e 75,3%. A estrutura anatômica do carvão pode ser utilizada na identificação de espécies. As espécies estudadas não são indicadas para a produção de carvão, pois o teor de cinzas e materiais voláteis é superior ao indicado para carvão produzido para uso doméstico. Além disso, porque o poder calorífico e o teor de carbono do carvão são insuficientes para uso na indústria siderúrgica.

Charcoal is an important energy raw material and its properties are influenced by the wood's anatomical and chemical composition and the production process. The aim of this study was to evaluate the anatomical characteristics, calorific power and volatiles and ash content of carbonized wood from Byrsonima spicata, Calophyllum brasiliense, Cecropia sciadophylla, Cochlospermum orinocense and Schefflera morototoni. The calorific power varied from 26,878 to 31,117 kJ kg-1; the content of volatile materials ranged from 20.9 to 31.7%; ash content ranged from 0.1 to 3.8%; and carbon content varied from 68.2 to 75.3%. Anatomical structures of charcoal can be used for species identification. The studied species are not indicated for charcoal production because the levels of ash and volatile compounds are higher than those recommended for charcoal produced for household use. In addition, the calorific power and level of carbon content are insufficient for use in the steel industry.