Avaliação da secagem do bagaço de malte para aplicação como biossorvente

Abstract

Brazil stands out as an agricultural producer today, having its agroindustrial production increased in recent years. As a result of the high production, the waste produced increased in the same proportion. In this way, research aiming at the rational use of these residues, together with the economy, have included the use of unit operations for material transformation and, among them, drying can be highlighted. This technique allows the product to be used, keeping it protected from enzymatic degradation. Given the increasing concern with the environment and the textile sector being responsible for a large portion of the generation of effluents containing dyes, it is necessary to use methods to treat effluents from these industries. Among the methods used for dye removal, adsorption stands out. However, on an industrial scale, large amounts of adsorbent material are required and, therefore, the application of alternative adsorbents, which bring greater economic viability to the process, is being studied. In this sense, biosorbents have stood out for having low added value, as they often come from other industrial processes. Based on this, the present paper aimed to investigate which drying method enhances the application of malt bagasse as an alternative biosorbent for the removal of the Neolan Black WA dye. For that, first, two drying methods were carried out: by oven and by microwave. Then, the drying temperatures were defined as being 50 °C, 80 °C and 110 °C and the microwave powers of 320W, 800W and 1600W. The experimental data were fitted to empirical models of drying kinetics, noting that Page was the one that best expressed the results. After drying, the samples were crushed and sieved with a granulometry of 48-60 mesh so that the kinetic and equilibrium tests could be carried out. In the kinetic test, it was possible to conclude that the pseudosecond order model was the one that best fitted the data, presenting R2 above 0.9 for all drying conditions tested. The equilibrium test ocurred by adjusting the experimental data to isotherms and the model that best fitted the data was the Langmuir model, with maximum adsorption capacity between 38.78 and 68.24 mg/g for the six samples of malt bagasse. In addition, the zero charge point test demonstrated that the type of drying method influences the surface charge of the solid, being 6.0 for the oven dried sample and 7.0 for the microwave dried one. Malt bagasse was characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR).