The manufacture of wood panels generates a large amount of waste. This material can be an option for renewable energy generation. However, long-term storage, exposure to moisture and contact of these panels with the soil facilitate colonization by xylophagous organisms. Torrefaction, a heat treatment between 200 and 300 °C in an oxygen-free atmosphere, is a process that decreases hygroscopicity while increasing carbon content, energy efficiency and resistance to fungal attack. This work aimed to evaluate the resistance of MDF panel residues. The MDF panels were produced using eucalyptus wood and bonded with thermosetting synthetic resin, under high temperature and pressure, torrefied at 300 °C for 20, 30 and 40 min and exposed to the xylophagous fungi of the white rot, Irpex lacteus (Fr.) Fr. (1828) and Trametes versicolor, and that of the brown rot, Postia placenta. After the 12-week evaluation period under fungal exposure, the mass loss of the samples attacked by T. versicolor and P. placenta was similar between treatments, except the MDF untreated, which had greater mass losses from the fungus Irpex lacteus. The torrefaction process increased the material resistance to deterioration by fungi, with an inverse correlation between the torrefaction period and the mass losses by fungal attack of the MDF panel residues.
Activated carbon (AC) is a carbonaceous material used to adsorb and remove pollutants. One of the requirements for the material to be considered a precursor in the AC production is its high levels of carbon. Therefore, a promising alternative for the use of forest biomass and its residues would be the application of these materials as precursors in the AC production. Owing to the productive capacity of activated carbon in Brazil and the considerable availability of forest biomass, the objective of the study was to approach the production and market of activated carbon in Brazil. This study is a bibliographic review focused on the use of forest resources for the AC production. AC production occurs by three methods: physical, chemical and physico-chemical activation. At the national level, the main production method is the physical one, since it has the least cost. However, the Sector still requires the researches and technologies aimed at the standardisation and improvements in the whole production chain.
O objetivo geral do estudo foi avaliar a eficiência de extratos tânicos de Acacia mearnsii no tratamento de madeiras de pinus densificada termomecanicamente, em relação às propriedades químicas, físicas, mecânicas, anatômicas e de resistência biológica aos organismos xilófagos. Madeiras da espécie Pinus elliottii com dimensões 7,0 cm x 3,3 cm x 27 cm foram pré-tratadas com ácido oxálico em reator Par à temperatura de 120 ° C por 90 minutos, e em seguida tratadas por difusão em soluções de taninos nas concentrações 5, 10 e 15%, e por fim, prensadas a 150 °C por 60 minutos. Propriedades químicas (teor de holoceluloses, lignina, extrativos, cinzas e FT-IR), físicas (retratibilidade, densidade aparente pelo método da balança hidrostática e por raios X, e permeabilidade), mecânicas (resistência a flexão estática, compressão paralela às fibras e dureza Janka), anatômicas (microscopia eletrônica de varredura) e resistência biológica da madeira a cupins de madeira seca (Cryptotermes brevis), foram avaliadas. A presença de taninos nas amostras de madeira modificada não foi identificada pela análise FT-IR. Houve redução da higroscopicidade e da permeabilidade da madeira modificada em relação ao pinus in natura. A densidade aparente da madeira modificada foi 87,8% maior em relação a madeira in natura para o tratamento na concentração de taninos de 15%. A resistência mecânica das madeiras modificadas aumentou para madeiras tratadas com taninos na concentração de 15%. Houve aumento da mortalidade dos cupins de madeira seca (Cryptotermes brevis) e redução do dano das madeiras modificadas tratadas com taninos na concentração de 15%. De maneira geral, as madeiras tratadas com taninos na concentração de 15% obtiveram os melhores resultados de resistência mecânica, biológica a cupins de madeira seca e para os parâmetros físicos. A madeira de pinus densificada e preservada com extrativos tânicos mostrou-se uma alternativa tecnologicamente viável como material construtivo de alto desempenho. Palavras-chave: Biodeterioração. Densificação termomecânica. Modificação da madeira. Preservante. Taninos.
Thermo-mechanical densification modifies wood to produce a more dense and resistant lignocellulosic material and may degrade extractives that contribute to the increased susceptibility of wood to attack by xylophagous organisms. This study evaluated the efficiency of tannin extracts of Acacia mearnsii in the treatment of thermo-mechanical densified pine wood in relation to physical, mechanical, and biological resistance (Cryptotermes brevis) properties. Pinus elliottii samples were pretreated with oxalic acid in a Parr reactor, then treated by diffusion in tannin solutions at concentrations 5, 10, and 15%, and finally hot pressed. The apparent density of the modified wood was 87.8% greater than that of the in natura wood (control) with tannins at 15%. The mechanical strength increased, especially the parallel compressive strength, which had an average increase of 169% for the wood with tannins at 10 and 15%, compared with the in natura wood. There was an increase in termite mortality and a reduction in damage for the modified wood treated with 15% tannins, obtaining the best results in mechanical and biological resistance and for the physical parameters. Thermal densification pine wood and preserved with tannin extractives proved to be a potential alternative as a high performance material.
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