No abstract

A perspectiva de escassez de água em um futuro próximo ilumina um alerta sobre o uso indiscriminado desse recurso, uma vez que sua disponibilidade é cada vez mais limitada. Esse fato faz com que as discussões sobre o uso consciente da água se tornem cada vez mais comuns por grupos ambientalistas, órgãos governamentais, pesquisadores e, muitas vezes, pela sociedade em geral. Nesse contexto, destaca-se a busca por adsorvente de baixo custo, pois em muitos casos, esse material deve ser utilizado em larga escala no tratamento de água, o que impede o uso de um material de alto valor. A extração de óleo de babaçu para produção de biocombustível tem sido extensivamente estudada, mas em muitos casos, a torta da extração de óleo é descartada, gerando inadequadamente impactos ambientais. Neste contexto, este trabalho tem como objetivo testar a adsorção do corante catiônico azul de metileno no babaçu, para tentar agregar valor a um material frequentemente descartado irregularmente, além de ajudar as indústrias têxteis na sustentabilidade em relação ao uso da água.

The combustion of different fuels gives rise to the formation of small but appreciable amounts of volatile organic compounds (VOCs). They basically result from incomplete combustion and their emissions have negative repercussions on health and on the environment in general. As their measurement is difficult, costly, and very time-consuming, very little is reported on the emissions of VOCs from combustion installations. In this study, various blends of two different coals with several wastes were burned in a pilot-scale fluidized bed combustor and measurements of VOCs at several locations along the combustor height as well as just before the stack were carried out. The results demonstrate that the parameters important for the formation of VOCs are temperature, excess air levels, and the effectiveness of the mixing of air with fuel. Furthermore, it was observed that coal was the principal source of VOCs, but the combustion of volatiles from fuels such as biomass, occurring in the freeboard, was important in reducing the emissions of VOCs to almost zero.

The feasibility of preparing chemically-activated carbons from a char obtained by the gasification of pine wastes has been studied. The optimised conditions for producing activated carbons with well-developed porosity were investigated and the influence of activating agent (KOH)/char ratio, temperature and duration of the pyrolysis process established. Additionally, for comparative purposes, two different designs for the stainless-steel basket in which the sample to be activated was inserted were tested in selected cases to determine the quality of the activated carbons produced. The results obtained showed that micropore development depended strongly on the KOH/char ratio, which was the most important variable under the conditions studied. The activated carbon with the largest adsorption capacity produced had a well-developed porosity, providing a total micropore volume of 0.678 cm3/g and an apparent surface area (as estimated by the DR method) of 1908 m2/g. The activated carbons prepared exhibited high benzene adsorption rates that increased with increasing micropore volume. The initial adsorption coefficient (γ) appeared to correlate strongly with the micropore volume deduced from nitrogen adsorption data.