Adsorção do corante têxtil Azul de Metileno usando como adsorvente a casca da castanha do Brasil “Bertholletia excelsa H.B.K.

Abstract

The liquid effluent generated by textile industries can cause serious environmental problems depending on their characteristics. These effluents usually contain dyes, which are organic compounds responsible for reducing or preventing the passage of sunlight, if released into rivers and lakes, causing a reduction in photosynthesis and affecting the aquatic life of the environment. In addition, when decomposing, under certain conditions, some dyes develop carcinogenic potential, becoming toxic to humans and ecosystems. Among the textile dyes present in these effluents, Methylene Blue (AM) stands out, which is a cationic dye that is difficult to degrade and presents great difficulty in its treatment. One of the most used treatment methods for this type of industrial effluent is adsorption, as it can achieve high removal efficiency, it is easy to operate and there is a wide range of adsorbent materials. Predominant factors for adsorption success are the appropriate choice of adsorbent, its economic feasibility and low toxicity. Thus, the search for alternative adsorbents from plant residues has intensified. The husk of Brazil nut (Bertholletia excelsa H.B.K.) is an abundant material available in the Amazon region, considering that for each ton of clean almond, around 1.4 ton of solid waste is generated. From what has been exposed, the aim of this work was to study the use of processed Brazil nut (Bertholletia excelsa H.B.K.) husk for application in the removal of Methylene Blue dye. Initially, the raw material was prepared by washing in running water, drying for 24 hours in an oven at 105 °C, grinding in a knife mill and sieving through a set of sieves and a shaker for 30 min. The powder obtained was named as an alternative adsorbent for the removal of AM present in the liquid phase. The influence of solution pH, adsorbent dosage and adsorbent granulometry were determined from batch adsorption tests. The particle sizes between 0 and 2 mm were evaluated, the adsorbent dosage was tested at 2, 4, 10 and 20 g/L, the adsorbent particle size effect was tested in the range of 0.05, 0.125, 0.25, 0.5 and 1 mm and the pH of the solution was evaluated in a range of 2, 4, 6, 8 and 10. The results of the granulometry indicated that the largest amount of mass retained was in the sieve that has an opening of 0.5 mm that corresponds to Tyler 32, where 52% of the initial mass was retained and the Sauter diameter was 0.527 mm. It is possible to evaluate and verify the influence of the parameters analyzed in the adsorption tests, in which the optimal dosage of adsorbent material was 10 g/L, combining the smallest amount of adsorbent with the highest dye removal efficiency, the best particle size was 0.5 mm and the optimum pH of the solution was pH 6, as this is the actual pH of the solution. Therefore, with these results, the processed Brazil nut husk is considered an alternative material for dye removal.