Remoção dos corantes azul de metileno e laranja reativo 64 por carvão produzido a partir de lodo de ETE

Abstract

The contamination of waterbodies by effluents containing dyes has been an object of attention to several scholars. The presence of dyes in the water reduces the transparency of the medium, hindering the penetration of solar rays and, consequently, affecting the execution of photosynthesis by the aquatic flora. In addition, the use of colored water is extremely limited, since its aesthetics is an indication of quality and, therefore, essential to the consumer. In this sense, several methods for treating colored effluents have been developed in the last decades. Among them, adsorption is certainly one of the most efficient, especially when performed with activated carbon, which undergoes physical-chemical treatments to ensure a high internal porosity. However, the cost of obtaining this adsorbent is usually very high. Therefore, as a less expensive alternative for the removal of dyes, the present work proposes the use of charcoal – whithout undergoing any activation processes – made from sewage sludge of a wastewater treatment plant. Starting from synthetic effluents based on methylene blue and reactive orange 64, the kinetics and the equilibrium of each dye were evaluated, concluding that methylene blue is adsorbed according to the kinetic model of pseudo-second order and is best described by the Langmuir isotherm, whereas the reactive orange 64 has its sorption kinetics responding to the pseudo-first order model and is best represented by the Freundlich isotherm. Using 0.040 g of charcoal, a 99.51% removal (absence of apparent color) was obtained for 10 mg/L methylene blue solutions. In the case of the reactive orange 64, using 0.25 g of charcoal, a 93.51% removal (absence of apparent color) was obtained in 10 mg/L solutions.