Activated carbons (ACs) of coconut shell produced by NaOH activation at impregnation ratios of
NaOH:char (w/w) equal to 1:1 (AC-1), 2:1 (AC-2) and 3:1 (AC-3) were prepared. The properties of these
carbons, including BET surface area, pore volume, pore size distribution, and pore diameter, were characterized from N2adsorption isotherms. It was found that the ACs are essentially microporous and that
the BET surface area was in order of 783 m2
g
−1
for AC-1, 1842 m2
g
−1
for AC-2, and 2825 m2
g
−1
for
AC-3. Scanning electron microscopy images showed a high pore development while Boehm method and
Fourier-transform infrared spectroscopy spectra indicated the presence of acid functional groups which
was confirmed by pH drift method. The adsorption equilibrium and kinetics of methylene blue (MB) onto
AC-3 were carried out. Experimental data were fitted to the four isotherm models (Langmuir, Freundlich,
Toth and Redlich–Peterson), and was found that Langmuir model presented the best fit, showing maximum monolayer adsorption capacity of 916 mg g
−1
. The kinetic studies showed that experimental data
follow pseudo-second-order model. The mechanism of the adsorption process was described from the
intraparticle diffusion model. The AC-3 has a high surface area and showed to be an efficient adsorbent
for removal of MB from aqueous solutions