Biosorption of Rhodamine B dye from aqueous solution by Rhus coriaria L. plant: Equilibrium, kinetic, thermodynamic and DFT calculations

•Water-soluble basic rhodamine B (RhB) was adsorbed onto fruit powders of Rhus coriaria L. (Anacardiaceae), sumac in batch reactions. Adsorption was optimized by changing concentration, pH, and time parameters.•Experimental data were in accordance with the Freundlich isotherm, adsorption obeyed the pseudo-second-order kinetics, and thermodynamic parameters indicated that adsorption was exothermic, spontaneous, and chemical.•Results were also evaluated by theoretical means: lowest Unoccupied Molecular Orbitals (LUMO), and the Highest Occupied Molecular Orbitals (HOMO).•HOMO energy values of the rhodamine B molecule had the highest activity with the B3LYP (-3.3729), with the HF (-6.0361), and with the M062X (-4.3299) levels.•Rhus coriaria L. adsorbent was for the first time used in this study for the removal of Rhodamin B.