Adsorption of Red 141 and methylene blue by cuttlebone: experimental and molecular dynamics study

Abstract

AbstractThe current study explores the removal of two organic dyes: Reactive Red 141, an anionic dye, and Methylene Blue, a cationic one, via adsorption onto a novel animal-derived biomaterial known as Cuttlebone (Sepia Officinalis). Before conducting experiments, an analysis of the biomaterial was performed. Subsequently, a sequence of experiments was undertaken to investigate the impact of different parameters on adsorption capacity. These parameters included mass of the adsorbent, pH level, duration of contact, and initial concentration of the dye. Findings indicate that Cuttlebone exhibits a more pronounced adsorption affinity for the anionic dye Reactive Red 141 compared to the cationic dye Methylene Blue (MB). The examination of adsorption isotherms for the respective adsorbent/adsorbate systems reveals that the adsorption behavior differs. Specifically, the adsorption of Red 141 on Cuttlebone conforms to the Langmuir model, while the uptake of MB on Cuttlebone shows a superior agreement with the Freundlich model. A peak adsorption capacity of 129.87 mg/g was noted for Red 141, while for MB, it was observed to be 23.86 mg/g. To elucidate the mechanism, the adsorptive characteristics of Red 141 and MB were validated using various methods, including Monte Carlo simulation (MC) and Molecular Dynamics simulation (MD). The results of MC and MD modeling demonstrate that Red 141 is significantly adsorbed onto calcium carbonate via the chemisorption phenomenon. Graphical abstract