PHYSICOCHEMICAL AND ENERGETIC CHARACTERISTICS OF TWO SPECIES OCCURRING IN THE BRAZILIAN SEMIARID

A vegeta\ue7\ue3o nativa da Regi\ue3o Nordeste vem sendo explorada e utilizada de forma intensiva e de maneira inadequada para finalidades energ\ue9ticas e nas constru\ue7\uf5es rurais, tornando-se evidente a import\ue2ncia dos conhecimentos relativos \ue0s caracter\uedsticas da madeira. Assim, essa pesquisa teve como objetivo avaliar as caracter\uedsticas f\uedsico - qu\uedmicas e energ\ue9ticas da madeira, os rendimentos da carboniza\ue7\ue3o e a caracteriza\ue7\ue3o do carv\ue3o vegetal das esp \ue9cies Poincianella pyramidalis Tul. L. P. Queiroz (Catingueira) e Handroanthus impertiginosus (Mart. ex DC.) Mattos (Pau-d\u2019arco). Para atender ao objetivo, foram abatidas cinco \ue1rvores de cada esp\ue9cie, amostradas aleatoriamente na Fazenda Santa B\ue1rbara, localizada no munic\uedpio de S\ue3o Mamede-PB. As \ue1rvores foram devidamente identificadas e transportadas para o Setor de Tecnologia de Produtos Florestais (STPF) da Universidade Federal de Campina Grande. De cada \ue1rvore, foram retirados toretes de 30 cm de altura a 0 (base), 25, 50, 75 e 100 % da altura comercial do tronco, considerada at \ue9 5 cm de di\ue2metro. Da por\ue7\ue3o mediana de cada torete, foi retirado um disco de 2,5 cm de espessura, subdividido em quatro partes, em forma de cunha, passando pela medula. Duas cunhas opostas foram utilizadas para a determina\ue7\ue3o da densidade b\ue1sica, e as restantes foram reservadas para a realiza\ue7\ue3o das an\ue1lises f\uedsicas, qu\uedmicas e energ \ue9ticas da madeira, os rendimentos em carboniza\ue7\ue3o e a caracteriza\ue7\ue3o do carv\ue3o produzido pelas esp \ue9cies estudadas. A densidade b\ue1sica foi determinada de acordo com o m\ue9todo da balan\ue7a hidrost\ue1tica e para a determina\ue7\ue3o da densidade b\ue1sica m\ue9dia de cada \ue1rvore utilizou-se como fator de pondera\ue7\ue3o o volume entre se\ue7\uf5es de cada disco. Ap\uf3s a secagem ao ar, as amostras destinadas \ue0s an\ue1lises qu\uedmicas foram transformadas em serragem e feitas determina\ue7\uf5es quantitativas de extrativos totais, da lignina, das cinzas, e o teor de holocelulose foi estimado por diferen\ue7a. As amostras destinadas \ue0 carboniza\ue7\ue3o foram transformadas em cavacos, e carbonizadas em forno el \ue9trico (mufla) por cinco horas e meia. Foram feitas determina\ue7\uf5es dos rendimentos dos produtos das carboniza\ue7\uf5es, e das propriedades f\uedsicas e qu\uedmicas do carv\ue3o vegetal. De modo geral, as madeiras estudadas apresentaram caracter\uedsticas f\uedsicas semelhantes. Com rela\ue7\ue3o \ue0s caracter\uedsticas qu\uedmicas, o pau-d\u2019arco apresentou maior teor de lignina (28,40 %), e n\ue3o houve diferen\ue7a significativa entre as esp\ue9cies para o teor de holocelulose. O poder calor\uedfico superior da catingueira exibiu os menores valores, para a madeira (4.413,50 kcal.kg-1) e carv\ue3o vegetal (6.247,80 kcal.kg-1), respectivamente. A catingueira apresentou um maior rendimento em carv\ue3o (43,03 %), mas de qualidade inferior. O carv\ue3o vegetal do pau-d\u2019arco apresentou o maior teor de carbono fixo (67,68 %). As esp\ue9cies apresentaram densidade verdadeira do carv\ue3o e rendimento em carbono fixo semelhantes. Pode-se concluir que as duas esp\ue9cies de ocorr\ueancia no semi\ue1rido Nordestino, apresentam boas caracter\uedsticas para produ\ue7\ue3o de carv\ue3o. De modo geral, o pau-d\u2019arco apresentou as melhores propriedades para fins energ\ue9ticos.The native vegetation from Brazilian Northeast has been explored and used intensively and inadequately as a source of energy and material for rural constructions. Now, it is recognized how important it is to get to know the characteristic of the wood produced by this vegetation. Thus, this study aims to provide information on the physicochemical and energetic characteristics of wood, carbonization yields and characterization of the charcoal from wood of Poincianella pyramidalis Tul. L.P.Queiroz and Handroanthus impertiginosus (Mart. ex DC.) Mattos. To meet the goal five trees from each species were cut down and randomly sampled at Santa Barbara Farm, located in the municipality of S\ue3o Mamede-PB. The trees were properly identified and transported to the Department of Forest Products Technology (STPF) at the Federal University of Campina Grande. Thirty centimeters sections were removed from each tree at 0 (base), 25, 50, 75 and 100 % of the commercial height (trunk diameter > 5 cm). A 2.5 cm thick disc was removed from the median part of each 30 cm section, and each disc was subdivided in four wedge pieces, passing through the trunk pith. Two opposite wedge pieces were used to determine the basic density of wood, ant the other two pieces were put aside in order to carry out physical, chemical and energetic analyses, carbonization yields and characterization of the charcoal produced by the studied species. Basic density was determined according to the method of hydrostatic balance and to determine the average basic density of each tree, the volume between sections of each disc was used as a weighting factor. After the air drying, the samples intended for chemical analysis were transformed into sawdust and quantitative determinations of total extractives were performed, lignin, ashes, and the holocellulose content was estimated by difference. The samples intended for carbonization were processed into chips, and carbonized in an electric oven (furnace) for 5h30mim. Determinations of the yield of products of carbonization were carried out as well as physical and chemical properties of wood charcoal. In general, the studied wood showed similar physical characteristics. Regarding to chemical properties, Pau-d\u2019arco wood showed a higher lignin content (28.40 %), and there were not any significant differences among species for the holocellulose content The superior calorific power of Catingueira wood (4413.50 kcal.kg-1) showed the lowest values for wood (4413.50 kcal.kg-1) and charcoal (6247.80 kcal.kg-1) respectively. The catingueira wood showed a higher charcoal yield (43.03 %), but lower quality. The Pau-d\u2019arco charcoal had the highest fixed carbon content (67.68 %). These species showed similar charcoal true density and fixed carbon production. It is concluded that the two species which occurs in the Northeastern semiarid, have good properties for charcoal production. The Pau-d\u2019arco showed the best properties for energy use