Monolayer–multilayer adsorption phenomenological model: Kinetics, equilibrium and thermodynamics

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 284; pp. 1328 - 1341
• Main Authors: Scheufele, Fabiano Bisinella, Módenes, Aparecido Nivaldo, Borba, Carlos Eduardo, Ribeiro, Caroline, Espinoza-Quiñones, Fernando Rodolfo, Bergamasco, Rosângela, Pereira, Nehemias Curvelo
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-01-2016
• Subjects: Dye aggregation; Multilayer adsorption; Phenomenological modeling; Rate-limiting step; Sugarcane bagasse characterization; Multilayer adsorption; Dye aggregation; Sugarcane bagasse characterization; Phenomenological modeling; Rate-limiting step
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2015.09.085

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•Predictive phenomenological multilayer adsorption model was developed.•Monolayer and multilayer adsorption of the RB5G dye controls the overall process.•Kinetics, equilibrium and thermodynamics were assessed through a unique approach.•Dye aggregation in the liquid phase was observed and investigated.•Mechanism and intermolecular interactions of mono and multilayer were identified.
A phenomenological model for multilayer liquid phase adsorption in closed and batch system was developed to assess the diffusional resistances and the adsorption rate-limiting steps. Equilibrium, kinetic and thermodynamic results indicated a multilayer adsorption behavior, wherein two adsorption steps were identified: (i) monolayer adsorption, with chemisorption characteristic binding energy due to synergistically electrostatic and H-bond intermolecular interactions; (ii) multilayer adsorption, favored by high dye concentrations and temperatures, however presenting a physical biding energy, related to less intense interactions such as H-bond and van der Waals forces. Additionally, dye aggregation in the liquid phase was observed and investigated. The proposed adsorption model allowed to investigate physically the kinetics, equilibrium and thermodynamics through a unique approach and to elucidate the mechanisms in distinct operational conditions. Hence, this mechanistic and predictive model can be used for the optimization and scale-up of the multilayer adsorption processes.