Fixed bed adsorption models

Model prediction and explanation

Thomas

Model

Thomas’s model predicted a dynamic adsorption which illustrated the future performance of adsorption for the best design of column adsorption (Auta, 2012) . This model assumed that the distribution of axes was neglected in column adsorption which defined Langmuir’s concept (Aksu & Gönen, 2004) . According to this model’s plot, the capacity of adsorption at equilibrium, q_o decreased while the constant, k_Th increased with an increased flow rate due to interaction time between solution and the limited adsorbent in the column (Auta, 2012) . The regression value, R² for this model was in between 0.7486 and 0.9527, which indicated the suitability of column adsorption study conducted.

Yoon and Nelson Model

Yoon and Nelson model assumed the probability of adsorbent molecule adsorbed was proportional to the probability of the adsorption of adsorbate (Tamilselvi & Asaithambi, 2015) . The constant, k_YN increased while t_0.5 (min), the breakthrough time needed for 50% of the materials to be adsorbed decreased with an increased flow rate. Adsorbent became saturated in a shorter time at higher flow rate, which lead to a reduced value of t_0.5 (min) (Tamilselvi & Asaithambi, 2015) . The regression value, R² for this model was in between 0.7486 and 0.9527, which showed that the model was suitable for column adsorption study.

Bohart-Adams Model

Adams Bohart model explained the beginning parts of the breakthrough time (Han et al., 2009) . This model assumed that adsorption process was continuous, and equilibrium could not be reached immediately (Sekhula et al., 2012) . Adams Bohart constant value, k_AB increased with increased flow rate. This indicated that the whole kinetic system was controlled by the movement of outer mass at the beginning of column adsorption (Aksu & Gonen, 2004) . The range of regression value, R² was lower than the others which lay in between 0.722 and 0.8383.