4.3. Effect of contact time and initial concentration
Fig. 3 shows the result for effect of initial concentration
(50–360 g/L) on adsorption of MB on PS at 30 ◦C. It was observed
that dye uptake was rapid for the first 20 min and thereafter it proceeded at a slower rate and finally reached saturation. The initial
rapid phase may be due to an increase in the number of vacant sites
available at the initial stage. Fig. 3 indicates that an increase in initial MB concentration leads to increase in the adsorption of MB on
PS. The equilibrium adsorption increased from 16.42 to 99.30 mg/g,
with increase in the initial MB concentration from 50 to 360 mg/L.
As the initial MB concentration increased from 50 to 360 mg/L the
equilibrium removal of MB decreased from 77.10 to 68.63%. Such
trend was reported on the adsorption of MB peanut hull [26].