Adsorption of phenol on microwave-assisted activated carbons: Modelling and interpretation

A theoretical study of phenol adsorption on microwave-assisted activated carbons has been performed using statistical physics models. These models have been selected based on the adsorption isotherms profiles and applied to obtain a detailed explanation of the phenol adsorption mechanism and to understand the adsorbent performance. In particular, the phenol adsorption was analyzed using a model that assumed two layers with different adsorption energies. Modelling results, based on the number of phenol molecules adsorbed per site, suggested that two relative positions of phenol adsorbed on activated carbon surface could occur. Besides, at high temperatures, an aggregation phenomenon of phenol molecules was also hypothesized and interpreted. This adsorption process was associated to two adsorption energies that characterized the interactions between phenol – adsorbent and phenol – phenol molecules. The analysis of adsorption energies indicated that all interactions were weak resulting in a physisorption process.