Adsorption of the Prototype Anionic Anthraquinone, Acid Blue 25, on a Modified Banana Peel: Comparison with Equilibrium and Kinetic Ligand–Receptor Biochemical Data

The adsorptive behavior of dye Acid Blue 25 (AB25) on the banana peel is studied with two objectives in view. First, from an environmental point of view, AB25 is considered a model of the anionic dyes, and the banana peel is a quite abundant agricultural waste which can be reused as adsorbent. Second, and on account of the recent research on possible applications of 1-aminoanthraquinone derivatives in pharmacological research, physicochemical studies on the interaction of AB25 anionic prototype and related dyes with different kinds of biomass surfaces can be useful in the basic modeling studies on the antagonist-P2 receptor interactions carried out by different researchers with 1-aminoanthraquinone dyes. A careful analysis of the acid–base properties of the biomass provides the number of weak acid groups, that was found to be 0.288(7) mmol g^–1 for modified banana peel in 0.1 M KNO₃. An uptake capacity value of 0.215(13) mmol g^–1 is obtained when data from batch experiments are fitted to sorption isotherms. Specific surface is calculated and compared with other biosurfaces. Kinetics of the process allows calculating an intraparticle diffusion coefficient, <i>D</i>_i, of 0.331(1) × 10^–13 m² s^–1. Desorption and column experiments demonstrate the feasibility for an application for AB25 recovery in remediation. Finally, a comparison with thermodynamic and kinetic data from receptor–ligand studies is also carried out