Incredulity on assumptions for the simplified Bohart-Adams model: 17a-ethinylestradiol separation in lab-scale...

In this study, the original Bohart-Adams model was employed to analyze the experimental data of 17α-ethinylestradiol (EE2) separation in lab-scale anthracite columns with low initial concentration. Besides, the assumptions for the simplified Bohart-Adams model were calculated and discussed. The results revealed that the breakthrough curves of EE2 separation in anthracite columns under different conditions were asymmetrical N-shaped and could be divided into three parts. The third part of the breakthrough curves was successfully fitted by the original Bohart-Adams model with high R² values (higher than 0.918) and low ARS values (less than 0.141). As expected, the assumptions for the simplified Bohart-Adams model were not tenable during the whole experiment process. As a result, the EE2 separation capacities (N₀° and N₀^s) obtained from the original and simplified Bohart-Adams model were quite different, and most N₀° values were greater than N₀^s values. The N₀° value used to evaluate the pollutant separation capacity in lab-scale column would be more accurate. In addition, physical interception and chemical adsorption simultaneously worked in the EE2 separation in anthracite columns. Physical interception and bed depth in anthracite columns at low flow rate were related in quadratic function (R² > 0.988).