Bifurcaria bifurcata activated carbon for the adsorption enhancement of Acid Orange 7 and Basic Red 5 dyes: Kinetics, equilibrium and thermodynamics investigations

Abstract

During this study, we investigated the adsorption efficiency of activated carbon prepared from the Bifurcaria bifurcata algae and activated by H2SO4 (CMBB@H2SO4) in comparison to two organic pollutants, the Acid Orange 7 (AO7) and Basic Red 5 (BR5) dyes. We investigated the effects of physicochemical parameters on the reaction environment in order to optimize adsorbent mass, pH, and contact time. We discovered 10 mg, 7.5 (pH unchanged) and 120 min for AO7 and 10 mg, 5.5 (pH unchanged) and 120 min for BR5. These ideal circumstances resulted in elimination rates of up to 88.8 percent for AO7 and 94 percent for BR5 from starting concentrations of 10 and 30 ppm, respectively. The pseudo-second-order model was the most appropriate to describe the adsorption kinetics of AO7 and BR5 on CMBB@H2SO4. The study of equilibrium isotherms revealed that the AO7 adsorption data were accurately modelled by the Langmuir model, but the BR5 data were more closely related to the Freundlich model. The maximum adsorption capacities (82.56 mg/g for AO7 and 185.91 mg/g for BR5) were obtained with just a ratio of 0.2 g/L. The thermodynamic behavior of the adsorption of the two dyes was more chaotic at the reaction interface. The overall performance of our CMBB@H2SO4 in terms of elimination efficiency, as well as the speed of the process and the ability to work without adjusting the pH, has demonstrated yet again that CMBB@H2SO4 could contribute to the reduction of contamination by the AO7 and BR5 dyes in aqueous solution.