where qe and qt are the amounts of RB19 adsorbed on the
adsorbent at equilibrium and at various times t, (mol g1), k2 is the
rate constant of the pseudo-second-order model for the adsorption
process (g mol1 min1). Plots of t/qt against t (Fig. 4) for the
adsorption of RB19 onto DAH-bentonite have been drawn to obtain
the rate parameters