Physicochemical and thermodynamic investigation of Ni(II) biosorption on various materials using the statistical physics modeling

The biosorption isotherms of Ni(II) on four agro-wastes (sugarcane bagasse, passion fruit wastes, orange peels, pineapple wastes) were studied experimentally and theoretically at different temperatures (298, 308, 318 and 328 K) using the statistical physics formulism. The double layer model with two biosorption energies was the more adequate to explain the biosorption process. The parameters like, number ions/molecules per site (n), density of receptor sites (NM), biosorbed quantity at saturation (Qbioso) and biosorption energies (− E1 and -E2) were estimated by numerical simulation. Thermodynamically, the entropy was also calculated to characterize the biosorption process. The results showed that the biosorption was exothermic and occurred by physisorption. The Ni(II) biosorption occurred by the formation of two layers on the biosorbents surface. The first layer was formed by electrostatic interactions, with energies varying from − 21 to − 14 kJ mol− 1. The second layer was formed by Ni(II)-Ni(II) interactions with energies varying from − 11 to − 5 kJ mol− 1.