Population growth and the development of cities requires large energy needs, however, it comes from fossil fuels such as oil, however, its use has unfavorable consequences to society related to its polluting effect. One way to slow down such damages is to use less polluting fuels, such as biofuels. Biodiesel is used as a suitable substitute for conventional diesel, since it is a renewable fuel obtained through the process of transesterification from raw materials such as vegetable oils, animal fats, used cooking oils, and also because Brazil presents only suitable for cultivating oilseed varieties. In order for biodiesel production to occur efficiently, the transesterification and esterification reactions require the presence of a catalyst. Basic homogeneous catalysis is the most used form of biodiesel production, but requires refined and water-free raw material. In addition, the commonly used catalysts (NaOH, KOH, etc.) are environmentally aggressive and require a neutralization step. Heterogeneous catalysts have been shown to be efficient in transesterification reactions, as they are reusable and do not require a neutralization step after the reaction. With this purpose, the objective of this work was to study the application of heterogeneous catalysts obtained from natural sources (dolomite, crab shell, eggshell and fish scales). They have some advantages such as abundance, low cost, porous structure and non-toxic. The heterogeneous catalysts studied are promising and viable in the transesterification reaction for biodiesel production.

Opencast mining drastically alters the landscape due to complete vegetation suppression and removal of topsoil layers. Precise indicators able to address incremental changes in soil quality are necessary to monitor and evaluate mineland rehabilitation projects. For this purpose, metaproteomics may be a useful tool due to its capacity to shed light on both taxonomic and functional overviews of soil biodiversity, allowing the linkage between proteins found in soil and ecosystem functioning. We investigated bacterial proteins and peptide abundance of three different mineland rehabilitation stages and compared it with a non-rehabilitated site and a native area (evergreen dense forest) in the eastern Amazon. The total amount of identified soil proteins was significantly higher in the rehabilitating and native soils than in the non-rehabilitated site. Regarding soil bacterial composition, the intermediate and advanced sites were shown to be most similar to native soil. Cyanobacteria and Firmicutes phyla are abundant in the early stages of environmental rehabilitation, while Proteobacteria population dominates the later stages. Enzyme abundances and function in the three rehabilitation stages were more similar to those found in the native soil, and the higher accumulation of many hydrolases and oxidoreductases reflects the improvement of soil biological activity in the rehabilitating sites when compared to the non-rehabilitated areas. Moreover, critical ecological processes, such as carbon and nitrogen cycling, seem to return to the soil in short periods after the start of rehabilitation activities (i.e., 4 years). Metaproteomics revealed that the biochemical processes that occur belowground can be followed throughout rehabilitation stages, and the enzymes shown here can be used as targets for environmental monitoring of mineland rehabilitation projects.

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Euterpe oleracea Mart. known as acai, it is a palm of bacaceous fruit, distributed throughout Brazil in states such as Amazonas, Pará, Maranhão, Rondônia and Tocantins. The objective of this work was to produce an acid-base indicator strip from the hydroalcoholic extract of the pulp of Euterpe oleracea Mart. to determine acidity by colorimetric method, also seeking to develop in a simple, fast and low cost, being an alternative way to be used in teaching Chemistry in experimental practical classes with the subject covered in Inorganic Functions in Teaching: Elementary, Middle and Higher. The methodology used was carried out in stages: (i) obtaining the acai pulp from the fruits of the açaizeiro, (ii) obtaining the extract from the pulp of Euterpe oleracea Mart., (iii) building a pH scale (0- 14), (iv) obtaining a pH paper from the hydroalcoholic extract, (v) identification of acidic and basic substances in everyday use with both the extract and the pH indicator paper, (vi) determining the acetic acid content in commercial vinegars, and (vii) a comparison of the results obtained from% acetic acid, both with the synthetic indicator (phenolphthalein) and with the natural indicator. Through the tests with the tape and with the pulp extract of Euterpe oleracea Mart. satisfactory results were obtained. Thus, the pH tape and the Euterpe oleracea Mart. pulp extract identified the acidic, basic and neutral substances of everyday life, showing an alternative for teaching with practical experimental chemistry classes, being financially viable, and exploring an application of Euterpe oleracea Mart. pulp. as forest treasure for future industrial applications, such as the production of a pH indicator strip.

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A espécie Iroxa chinensi conhecida popularmente como alfinete gigante, que é utilizada no preparo de extratos hidroalcoólicos utilizados como indicadores naturais de substâncias ácidas e básicas. Esse estudo teve como objetivo obter uma solução hidroalcóolica indicadora ácido-base a partir da espécie Iroxa chinensi para teste qualitativo (visualização da coloração em soluções ácidas e básicas do dia a dia) e teste quantitativo (determinação da porcertagem do teor de ácido acético em vinagres comercializados no município de Breves no Estado do Pará). Esse estudo foi realizado em várias etapas, a saber: o preparo do extrato hidroalcoólico a partir da Iroxa chinensi e posteriormente a produção de fitas de pH; testes utilizando tanto o extrato quanto a fita de pH em soluções preparadas e produtos do cotidiano; e determinação do teor de ácido acético em vinagres comerciais. Os resultados mostraram a eficiência do extrato hidroalcoólico da Iroxa chinensi como indicador natural de ácido-base, assim como a fita de pH mostrou-se uma ferramenta viável na identificação de substâncias ácidas e básicas. Portanto, existe um potencial na utilização de indicadores naturais para identificar substâncias ácidas e básicas do dia a dia, levando em consideração a fácil obtenção desses recursos, baixo custo e eficiência nos resultados obtidos, podendo assim substituir indicadores sintéticos, além de ser uma ferramenta que pode ser facilmente produzida e trabalhada em sala de aula.

Adsorption is a surface phenomenon, in which the adsorbate is adhered to an adsorbent material and have been study for the removal of textile dyes, which have high toxicity to the aquatic environment. One of the dyes that stands out is methylene blue, which is organic, basic, aromatic, heterocyclic and molecular formula (C16H18ClN3S). In this study, we aim was to carry out a bibliography review in national and international scientific journals with articles published in the period from 2005 to 2019, of the adsorbent materials for the adsorption of the methylene blue dye. The materials reported are: mango seed powder, wheat husks, activated carbon obtained from rattan sawdust, activated carbon prepared from coconut shell, garlic shell, NaOH modified pummell shell, activated carbon (coconut shell and modified with NaOH), activated carbon (pea peel), HCl modified watermelon peel, potato peel, ZnCl2 activated cashew nut peel, mesoporous carbon obtained from fish scales, pineapple peel and bamboo. Our review indicate that the adsorbent materials found in the literature for methylene blue adsorption have high adsorption capacities. The adsorption capacities are high and depend on several parameters, which influence the adsorption (pH of the medium, mass and particle size of the adsorbent material, concentration of adsorbate (methylene blue), temperature and time of contact of the adsorbate with the adsorbent.