C0 is the highest initial RB19 concentration (mol dm3). If the RL
values are between 0 and 1, the adsorption is favourable [26]. The
calculated value of RL was found to be 0.046 at 20 8C from Eq. (5)
and is given in Table 2. The result indicates that the adsorption of
RB19 ions onto DAH-bentonite is favourable