Single and binary adsorption of cobalt and methylene blue on modified chitin: Application of the Hill and exclusive extended Hill models

For better understand the adsorption process, the adsorption isotherms network of cobalt and methylene blue on modified chitin were constructed at identical conditions (298, 308, 318 and 328 K, pH 6) in single and binary systems. In order to interpret the adsorption isotherms, two statistical physic models 'Hill and the exclusive extended Hill models' containing some significant parameters were developed and selected. From theoretical observations and based on the simulation results, the study of the number of molecules per site indicated that the adsorbed molecules aggregate during the adsorption process and showed that an inhibition effect was created between the adsorbed molecules in single and binary system, respectively. Energetically, the interactions between the adsorbate molecules and adsorbent surface were governed by the adsorption energy showing that physisorption occurred. The single and binary systems were characterized by probable mechanisms describing the interaction, during the adsorption process, between the adsorbates and modified chitin, in agreement with the statistical physics parameters.