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The aim of this paper was to analyze energy-related properties of forestry and agricultural wastes for energy production purposes, and to compare them with fossil fuels. The forestry wastes used were red cedar, Eucalyptus, and Pinus wood shavings. The agricultural wastes analyzed were rice husk, coffee wastes, sugar cane bagasse, maize harvesting wastes, and bamboo cellulose pulp. The forestry wastes presented more suitable properties for bioenergy production than the agricultural wastes. Desirable energetic properties were found for coffee wastes. The opposite was verified for rice husks. Among the biomass studied, coffee wastes presented the highest equivalent in fossil fuel volume and hence may lead to the highest decrease in CO 2 emissions by fossil fuels used in Brazil for steam and heat production. The results suggests that CO 2 benefits can be obtained if bioenergy is generated in the same locale where biomass is produced, avoiding CO 2 cost of logistics and leading to greater end-use efficiency. The present work promotes the widespread use of different lignocellulosic wastes for bioenergy production and gives useful information for the planning and the control of power plants using biomass.

This study aimed to evaluate reaction conditions for deposition of SiO2 nanoparticles on the surface of cellulose fibers and their influence on moisture adsorption of the hybrid organic-inorganic material formed. SiO2 nanoparticle deposition was carried out with the sol-gel process testing four reaction times (2, 12, 18, and 24h) and three contents of the tetraethyl-orthosilicate (TEOS) precursor (1.9, 4.2 and 8.4g g(-1) of cellulose fiber). Modification time and TEOS content directly influence the amount of Si deposited on the fiber surface, nanoparticle diameter distribution, thermal stability, and resistance to moisture adsorption. There is a tendency of slight increase of nanoparticle size and the amount of Si deposited with increasing reaction time. SiO2 nanoparticles were bonded on the surface of the cellulose fibers and are able to improve thermal stability of the material, increasing onset degradation temperature. The moisture adsorption capacity of the modified cellulose fiber was reduced up to 50%.

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A wide range of alternative cellulose fibers for the development of new green nanomaterials can be obtained from Brazil's natural resources. The objective of the work is to evaluate the influence of the chemical composition of hardwoods on the nanofibrillation process and optical quality of nanofiber films. Wood wastes were selected from three native Amazonian species and from exotic planted Eucalyptus grandis species. Wood sawdust was submitted to chemical alkali and bleaching pretreatments. Nanofibers were produced from the bleached fibers after 10, 20, 30 and 40 passes through a Super Mass Colloider grinder, and films were produced by the casting method. Raw sawdust, alkali-treated fibers and bleached fibers were evaluated by the major chemical components, syringyl/guaiacyl ratio, Fourier transformed infrared spectroscopy, oxygen/carbon ratio and scanning electron microscopy. Morphological characteristics of nanofibers and films were analyzed by transmission and scanning electron microscopies. Optical parameters studied for the films were the opacity, total color difference and b value. The main challenge to delignification was attributed to the low syringyl/guaiacyl ratio. The different chemical natures of Amazonian and eucalyptus hardwoods greatly affected pretreatments and, consequently, the nanofibrillation and optical quality of the films. Consequences observed for highly purified cellulose starting fibers are: (1) lower diameters for individual nanofiber elements; (2) fewer opaque and colored films produced from nanofibers; (3) a tendency to stabilization of the nanofibrillation process after 20 passes through the grinder. For species whose chemical nature hindered cellulose purification, the increased number L. Bufalino (of passes through the grinder continuously decreased the opacity.