ABSTRACT:The use of biomass for biochar production is already a reality. However, little is known about its structure and composition, mainly due to the changes occurred during the heat treatment. This information is crucial since it will have an immediate impact on the quality and applicability of the material produced. Therefore, this study aimed to analyze different biomasses, characterizing their potential for biochar production. Woods from Eucalyptus urophylla and Corymbia citriodora and coffee husk were assessed. The biomass was ground and sieved, and then stored under controlled conditions of temperature and humidity. Subsequently, the material characterizations were performed through proximate analysis, elemental analysis, thermogravimetric analysis and Fourier transform infrared spectroscopy (FTIR). In general, all biomasses presented potential to be used in the production of biochar, where low H/C and O/C ratios were found. The coffee husk has higher lignin, extractives, ash and fixed carbon contents, which certainly contributed to its greater thermal stability. The FTIR analysis showed the presence of bands related to recalcitrant chemical groups such as carboxylics and phenolics in the spectra of all biomasses. The thermogram profiles of the C. citriodora and E. urophylla wood were similar to each other, and different from that of the coffee husk, which showed higher thermal stability. CARACTERIZAÇÃO DE DIFERENTES BIOMASSAS VEGETAIS PARA PRODUÇÃO DE BIOCARVÕESRESUMO: A utilização da biomassa para produção de biocarvões já é uma realidade. Porém, pouco se sabe sobre a sua estrutura e composição, principalmente, mediante as transformações ocorridas durante o tratamento térmico. Estas informações são fundamentais, uma vez que terão impacto imediato na qualidade e aplicabilidade do material produzido. Portanto este trabalho objetivou analisar diferentes biomassas, caracterizando-as como potenciais para produção de biocarvões. Foram utilizadas madeiras de Eucalyptus urophylla e Corymbia citriodora e cascas de café. As biomassas foram moídas e peneiradas e, em seguida, armazenadas sob condições de temperatura e umidade controlada. Posteriormente realizou-se a caracterização dos materiais, por meio de análise química, química imediata, elementar (CHNS-O), térmica (TGA e DTA) e de espectroscopia vibracional na região do infravermelho (FTIR). De forma geral, todas as biomassas apresentaram potencial para serem utilizadas na produção de biocarvão, no entanto, a casca de café apresentou maiores teores de lignina, extrativos, cinzas e carbono fixo, o que, certamente, contribuiu para que a mesma apresentasse maior potencial de utilização como condicionador de solos. Com relação à análise de FTIR, observou-se a presença de bandas referentes aos grupos químicos recalcitrantes, como os carboxílicos e fenólicos nos espectros de todas as biomassas. O perfil dos termogramas de C. citriodora e de E. urophylla foram semelhantes entre si e diferentes da casca de café, que apresentou maior estabilidade térmica.

Surface modification may lead activated carbon (AC) to take on different properties. This study aimed to promote surface modification of activated carbons using corona treatment (electrical discharge). In this study, powdered commercial activated carbon was used. Activated carbons were subjected to corona treatment at different exposure times (2, 5, 8 and 10 min) at 4.5 cm height from the source. To observe differences promoted by treatment, activated carbons were analyzed by acidity, surface functional groups, Fourier Transform Infrared Spectroscopy (FTIR), elemental analysis (ChN), proximate analysis and thermogravimetry. Corona treatment impacted surface chemistry of activated carbons. There was a trend of increasing surface acidity according to exposure time. There were changes in functional groups, increasing carboxyl acid and decreasing lactone and phenol groups. FTIR analysis showed peaks in the bands at 3500, 1650 and 1300 cm-1. Increase of oxygen content and decrease of carbon content were also found. Immediate analysis followed similar tendency for volatile and fixed carbon content. There were also differences in thermogravimetry analysis. Treated activated carbons were different compared to virgin activated carbon. This difference was performed by surface oxidation. Thus, this study showed that corona treatment caused surface modifications and might impact adsorption process.

The raw materials commonly used to produce pulp and paper in Brazil are woods from planted forests. Although with tremendous potential, the use of non-wood fibers is inexpressive. This study thus aimed to evaluate the use of sugarcane bagasse and bamboo to produce pulp and paper via physical, chemical and anatomical characterization, and to verify the influence of its properties on the process and the final product. Anatomical analysis of the fibers was performed (length and width from fibers and vessels, lumen width and cell wall thickness), as well as chemical component analysis (cellulose, hemicellulose, lignin, extractives and ash) and basic density of the materials. Moreover, felting rate, Runkel, Mulsteph and Boiler indexes, flexibility coefficient and wall fraction were generated. Results showed that both materials differed statistically in chemical properties, except for lignin content; density and anatomical properties, excluding vessel width and felting rate. Bamboo presented higher values cellulose (52.96%), minerals (2.34%), density (0.461 g/ cm³), wall fraction (67.84%) and Runkel (2.11), Mulsteph (0.90) and Boiler indices (0.81) values, whereas sugarcane bagasse presented higher hemicellulose (17.63%), extractives (12.81%) and flexibility coefficient (46.19%) values. Most properties were similar to those observed in raw materials commonly used for this purpose. Therefore, these two materials have potential for use in the pulp and paper industries.

For several wood uses, such as pulp, paper and charcoal, the presence of the bark is undesirable, compromising production. Thus, this study aimed to evaluate the influence of different plant spacings on the properties of the bark of a clone of Eucalyptus grandis x E. camaldulensis at seven years of age at five different plant spacings. The wood discs were removed from the trees at 0, 25, 50, 75 and 100% of the commercial height; then we performed thickness, basic density, gross calorific value and mineral content analysis of bark. There were no significant differences among treatments for the bark gross calorific value and thickness. For the bark basic density, the highest values were found in trees planted in wider plant spacings and considering the mineral content, there was a significant difference only for P, Mn and Zn.

The main and new surface modification methods of activated carbon (AC) and their influence on application (adsorption capacity) were reviewed. Adsorption capacity is an important issue, contributing to hazardous substances environment management. According to literature, it is true that surface chemistry strongly affects adsorption capacity. Surface chemistry can be modified by several methods that lead to different activated carbon properties. Furthermore, adsorbate properties, and their relationships with surface structure, can impact adsorption properties. Surface modifications can be conducted by adding some atoms to the surface structure, making the surface more acidic or basic. Introduction of oxygen and ammonia atoms (chemical modification) are the main processes to make the surface more acidic and basic, respectively, although may bring chemical wastes to environment. Surface modification is done by chemical and physical modifications that lead activated carbons to present different properties. The main and new methods of chemical and physical modifications are compared and presented in this paper. Some new physical methods, like corona treatment, plasma discharge and microwave radiation, can be applied to cause surface modifications. Corona treatment can be a practical and new way to cause surface modification on an activated carbon surface.