Eficiência de adsorção de microplásticos de poliestireno por carbono ativado modificado com óxido de ferro

Abstract

Microplastic pollution has emerged as a threat to aquatic ecosystems and human health due to its persistence against conventional treatment methods and its ability to adsorb and transport chemical pollutants. This study aimed to investigate the efficiency of granular activated carbon (GAC), both commercial and modified with iron oxide, in the removal of polystyrene microplastics (MPs) from aqueous solutions through adsorption processes. The modification of activated carbon by impregnation with iron oxide resulted in a significant increase in removal efficiency. The CBT-FeT6 showed better adsorption capacity compared to CBT-PD02, especially across a wider pH range, which is advantageous for real-world applications. At a concentration of 2.5 g/L, CBT-FeT6 exhibited equilibrium adsorption capacities (16 h) of 2.94 mg/g at pH 4 and 2.61 mg/g at pH 7, outperforming CBT-PD02, which showed equilibrium values (30 h) of 2.91 mg/g at pH 4 and only 0.63 mg/g at pH 7. Even at pH 10, where electrostatic repulsion predominated, CBT-FeT6 achieved an adsorption capacity of 1.07 mg/g using 2.5 g/L over 30 h. The adsorption isotherms followed the Langmuir model for CBT-FeT6 and the Freundlich model for CBT-PD02, suggesting that the adsorption process was favorably altered by the incorporation of iron oxide. Characterization tests revealed the chemical and morphological properties of both polystyrene and activated carbon, with SEM analyses confirming the experimental results. The study highlights the potential of iron oxide-modified activated carbon as an efficient and sustainable solution for the removal of polystyrene microplastics, emphasizing the need for additional treatment steps in Wastewater Treatment Plants (WWTPs) to combat the environmental threat posed by microplastics.