Insights into adsorption theory of phenol removal using a circulating fluidized bed system

Phenol is one of the most dangerous industrial pollutants in water sources due to its toxic effects on humans and animals. The adsorption process using activated carbon is one of the applicable methods that can be used to remove phenol traces and it is found to be the most efficient due to its various advantages. The present study investigates phenol adsorption using activated carbon which was hand coated onto glass beads. Various calculations were conducted with the data obtained from batch and column adsorption. Kinetic model analysis indicated that the system was best suited for pseudo-second-order kinetics. Thermodynamic parameters such as a change in enthalpy, change in entropy, and change in Gibbs free energy were evaluated, and it can be inferred from the results that this adsorption is endothermic and non-spontaneous for batch study. Physisorption can be inferred from low values of change in enthalpy and change in Gibbs free energy. From the two diffusion models, it was concluded that there is more than one ratelimiting step. The Temkin isotherm model, among the various isotherm models studied, was found to have the best fit with an R2 value of 0.987. The energy value (E) estimated using the Dubinin- Radushkevich isotherm model also proved that the system is physisorption in nature. The column study kinetic calculations indicated that for the column experiment, the process followed was the second-order kinetic model and the thermodynamic report concluded the process to be spontaneous and feasible. MATLAB coding was done for the entire calculations involved in the project, which can be utilized for future applications. (c) 2023 The Author(s). Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).