Effect of initial concentration and contact time
The ability of PLAC-B to remove methylene blue at various
initial concentrations (5e400 mg/L) is shown in Fig. 6. The
removal of methylene blue onto PLAC-B was rapid at the initial
period of contact time which became slow and stagnate with the
increase in contact time. Generally, PLAC-B shows a high capability
to reach saturation of methylene blue removal for the first
120 min. After 120 min, no difference in the amount of methylene
blue uptake was observed indicating the equilibrium has been
attained. This phenomenon can be attributed to the driving force
to overcome the mass transfer resistance on the adsorbent phase
through the use of high concentration of methylene blue. After a
period of time, it is assumed that no further adsorption takes
place. PLAC-B showed the ability to completely remove
5e200 mg/L of methylene blue within 15 min with maximum
removal of 0.16 mg/g (5 mg/L), 0.76 mg/g (10 mg/L), 2.23 mg/g