Mathematical modelling of dye removal from aqueous solution in a fixed bed column using exfoliated graphite as adsorbent

Colored dye effluents pose a major threat to surrounding ecosystem and many of them are extremely toxic. Adsorption process in fixed bed columns has been widely used in industrial processes for dye removal from textile effluents. Mathematical modeling of the process can be very useful to evaluate the efficiency of the process as well as optimizing design and operational parameters. In this work the use of exfoliated graphite has been investigated as an adsorbent for removal of C.I Acid Blue 92. First the equilibrium behavior was obtained through a series of batch tests at constant temperature and experimental data were fitted to various isotherm models. The results have shown that adsorption behavior of the dye could be described reasonably by Radke-Prausnitz model as well as that of Langmuir. Then a linear driving force for the rate of adsorption and an axial dispersion model for dynamic behavior of fixed bed adsorber with nonlinear adsorption isotherm were formulated and solved numerically. Finally the mathematical model was validated through a comprehensive experimental study on the breakthrough curves of the C.I Acid Blue 92 adsorption over wormlike exfoliated graphite in a laboratory size column.