Remoção do corante RB5 usando carvão de reuso

Abstract

Activated carbons (AC) are widely used in domestic water purifiers for the removal of organic compounds, chlorine, odors, and micropollutants. After a certain period of use, the used ACs are replaced with new ones, generating waste. Thus, the objective of this study was to evaluate the reuse potential of discarded ACs from purifiers (CAP-U) in the removal of the reactive textile dye black 5 (RB5), comparing their absorption capacity with that of a new AC (CAP-N). The activated carbon was obtained from a local supplier using discarded refills and one new refill. The refills were opened and the activated carbon was removed. The CAP-U sample was dried at 105ºC for 3 hours. Due to its previous use, CAP-U showed a reduction in specific surface area and pore volume, which contributed to the decrease in RB5 dye removal compared to CAP-N. The pHpcz values for the CAP-U and CAP-N samples were 6.38 and 7.52, respectively. The kinetic curves for both carbons showed similar behaviors, with greater removal in the first hours of contact tending towards equilibrium after 85 hours. The pseudo-second-order model best represented the kinetic data for both adsorbents. The adsorption isotherms at 30 °C showed a favorable shape with maximum adsorption amounts of 36.06 mg g⁻¹ and 14.46 mg g⁻¹ for CAP-N and CAP-U, respectively. The Freundlich model better represented the equilibrium data than the Langmuir model. It is worth noting that CAP-U was evaluated directly after use, without any type of physical or chemical treatment, and even so, it still showed a removal capacity of 40% compared to new charcoal. Thus, the discarded charcoals show potential for reuse in other processes, such as in the treatment of textile effluents, indicating an alignment with the principles of the circular economy.