The adsorption kinetics of CPX was evaluated for a starting
concentration of 10 mgCPX L−1 for all samples. The concentration
decreased drastically in thefirst 5 h then a slow but gradual removal
of CPX was observed until equilibrium was reached after 3 days.
Usually, a longer period of time is needed for equilibrium; however,
small adsorbent particle sizes were used in the experiments
to eliminate mass transfer limitations, accelerating the adsorption
process, since the rate of adsorption is inversely proportionalto the
square ofthe adsorbent particle diameter [30]. Fig. 4 shows thatthe
time required to reach equilibrium is shorter in the case of CX, since
it has larger pore size (Table 1), followed by CNT and AC. As the
AC sample also has micropores (Table 1), a longer time is needed
to reach adsorption equilibrium, due to the diffusion process that
occurs in such kind of pores