Análise da capacidade de adsorção de corantes em microplásticos de poliamida

Abstract

Thermoplastics are widely used materials for numerous functions today, and their properties have made it possible to meet various demands, making their manufacture necessary. However, the high production associated with the irregular disposal of these materials caused great worldwide concern since they are developed using additives that increase their resistance while suffering degradation over time, reducing their size and can change their properties. Thermoplastics discarded into the environment are susceptible to different factors that cause their degradation, transforming them into microplastics and facilitating their dissemination to the farthest places and different biotas what results in the omnipresence of microplastics on our planet. Associated with this, it implies the adsorption capacity of microplastics that allows them to carry different compounds at their interface, with an emphasis on toxic and polluting compounds. An emerging pollutant that stands out is dye because it is widely used in several industrial sectors and is commonly dumped in their effluents. When in an aquatic environment, dyes can cause toxicity to organisms and eutrophication of waters, reducing dissolved oxygen and the passage of light, in addition to their potential carcinogenic effects. Thus, the purpose of this final undergraduation project aimed to analyze the adsorption capacity of food dyes in contact with Polyamide microplastics to evaluate the transport potential that these MPs may exhibit. The experimental methodology was based on the literature, being analyzed by XRD, FTIR and SEM, in addition to tests for the elaboration of the adsorption kinetics that made it possible to find the most adequate model for the reaction that occurred. The results were compared among the pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. It was found that PA microplastics demonstrated a higher adsorptive capacity for the Ponceau dye, when compared to Tartrazine, indicating a stronger interaction between them and an approximate contact time of 2880 minutes under agitation to reach equilibrium, depending on the amount of microplastic used. It was also observed that the pseudo-second-order kinetic model was more appropriate for the reaction that occurred.