As part of efforts to reduce pressure on the Amazon and other biomes, one approach considered by Brazilian authorities and scientists is more intensive use of the soils of the interior of the northeast of the country, which are generally sandy, with low contents of organic matter and low water holding capacity and are frequently affected by severe droughts. In this work, biochars produced from waste biomasses were tested for the improvement of these soils. The highest BET (Brunauer-Emmett-Teller) specific surface areas were observed for all biochars. In the pH range studied, the water hyacinth plants (WH) sample showed the most negative zeta potentials, as well as the highest water holding capacity (WHC) values, while the zeta potentials of two quartzarenic neosol soils were consistent with their WHC values. The results suggested that despite the effect of porosity on water retention, the zeta potential could be associated with the presence of negative charges by which hydrated cationic counterions were absorbed and retained. The surface energy and its polar and dispersive components were associated with water retention, with sugar cane bagasse, orange peel, and water hyacinth biochars presenting higher SE values and larger polar components.

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This work shows the synthesis and characterization of graphite-like materials produced from the pyrolysis of biomass, obtained from industrial waste. The product has shown interesting electrochemical characteristics for application in the formation of a composite material with polyaniline, creating a perspective of application in a so-called “waste” helping to avoid environmental issues associated with this industrial disposal. The raw pyrolyzed material was further separated into nanosized structures by applying high-potency ultrasonic radiation, which was used in the modification of flexible electrodes of polyaniline, resulting in a composite material. Thermogravimetric analysis, electrochemical experiments, electrochemical impedance spectroscopy, Raman spectroscopy, and electronic microscopy were used for the characterization of the material itself and the composite electrode. The interaction between the modified graphite-like materials and polyaniline produced a high superficial area electrode, in a one-step synthesis. Such composite material favors the intrinsic conductivity of the conducting polymer, which was confirmed by the enhancement of its electrochemical and interfacial properties even in milder electrolytes, generating good perspectives for other electrochemical applications. These results demonstrate the potential of developing this composite material in energy storage electrodes.

Concern about environmental contamination by sulfur-containing gases has increased restrictive fuel legislation. The main process used to remove sulfur from fuel oils is hydrodesulfurization, however, due to some restrictions, new alternative processes are being studied, such as adsorption. Shale fuel oil for industrialization must reduce sulfur content to less than 1.00% by weight. In this work, the adsorbent materials were produced with two shale processing by-products: retained shale (the rock after processing) and shale fines (smaller granule size than that used in the process) for partial removal of sulfur compounds from the oil shale. These materials were produced at 350°C and 600°C, in two different granulometry and with CuCl 2 and CuSO 4 as Cu (II) source. The characterization was performed by elemental analysis, thermal and spectroscopic methods. Adsorption tests were performed with these materials and determination of sulfur content in shale fuel oil. The total deposition of copper in the prepared material ranged from 1.80 to 8.13% by weight. The capacity of the prepared adsorbent materials was 0.05 to 0.16 mg S g-1 of the adsorbent. A preocupação com a contaminação ambiental por gases contendo enxofre aumentou a legislação restritiva sobre combustíveis. O principal processo usado para remover o enxofre dos óleos combustíveis é a hidrodessulfuração, entretanto, devido algumas restrições, novos processos alternativos estão sendo estudados, como a adsorção. O óleo combustível de xisto para a industrialização precisa reduzir o teor de enxofre para menos de 1,00% em peso. Neste trabalho, os materiais adsorventes foram produzidos com dois subprodutos do processamento de xisto: xisto retortado (XR-rocha após o processamento) e finos de xisto (FX-tamanho de grânulo menor que o usado no processo) para remoção parcial de compostos de enxofre do óleo de xisto. Estes materiais foram produzidos a 350°C e 600°C, em duas granulometrias diferentes e com CuCl 2 e CuSO 4 como fonte de Cu (II). A caracterização foi realizada por análise elementar, métodos térmicos e espectroscópicos. Foram realizados testes de adsorção com esses materiais e a determinação do teor de enxofre no óleo combustível de xisto. A deposição total de cobre no material preparado variou de 1,80 a 8,13% em peso. A capacidade dos materiais adsorventes preparados variou de 0,05 a 0,16 mg S g-1 do adsorvente.