Adsorção de corantes e efluentes têxteis utilizando levedura residual: estudos cinéticos e de isotermas

Abstract

The Brazilian textile industry is the fourth largest producer of knits in the world, whose dyeing process results in a large volume of effluents due to inefficient water use and incomplete fixation of dyes on fibers, generating a significant environmental problem. Thus, these effluents must be properly treated, with adsorption being one of the most commonly used techniques for this purpose. One advantage of this process is the potential for reusing waste from other industries as adsorbents, such as Saccharomyces yeast biomass, which is the second largest byproduct of the brewing industry and has significant biotechnological potential. In this context, this study evaluated the adsorption of a textile dye onto S. pastorianus yeast isolated from the beer production process as a destination to exploit the potential of this waste. Adsorption tests showed good performance with reactive black 5 dye, with a maximum adsorption capacity of 164 mg/g, reaching equilibrium in less than 30 minutes, and best fitting to pseudo-second-order kinetic models and Langmuir isotherm. After adsorption, the pure and saturated biomass was characterized by SEM, FTIR, and finally, the pure biomass was characterized by nitrogen adsorption and desorption, methods through which it was possible to show that the adsorption process indeed occurred, as well as obtain morphological information of the surface. Dye desorption was also evaluated, indicating the possibility of reusing the adsorbent as 60% of the adsorbed dye can be recovered through treatment with a 0.1 M NaOH solution. COD analysis of the real effluent proved inconclusive due to interferents in its determination, but the adsorbent appears to be effective for remediating real effluents due to the reduction in turbidity and intensity of effluent color.