Valorization of food wastes (orange seeds) as adsorbent for dye retention from aqueous medium

AbstractIn order to understand the adsorption process mechanism and to evaluate the adsorptive properties of the citrus powder, the equilibrium, thermodynamic, and kinetic of the adsorption of the anionic reactive dye Orange 16 on the powder of orange seeds were studied using different theoretical models. The equilibrium adsorption data analyzed by Freundlich, Langmuir, and Dubinin–Radushkevich isotherm models revealed that Langmuir model best describes the dye sorption processes. The monolayer adsorption capacity of 1,111.11 mg/g reached at 25°C and the values of the mean free energy (E) obtained from the Dubinin–Radushkevich model (5.45–6.48 kJ/mol) indicated a porous structure of the adsorbents and suggest that the physical adsorption is the main adsorption type involved in this studied processes. The values of the thermodynamic parameters (ΔG, ΔH, and ΔS) showed that the adsorption of tested dyes was feasible, spontaneous, and endothermic under examined conditions. The FTIR spectroscopy was used to ch...