Adsorptive Removal of Chromium(VI) from Aqueous Solution by an Agricultural Waste-Based Activated Carbon

Activated carbon was prepared from an
agricultural waste, coconut coir, and its characteristics
were compared with that of a commercial
bituminous coal-based activated carbon. The activated
carbon possessed higher surface area, micropore
area, micropore volume and average pore
diameter, and well-developed meso- and micropores.
Batch test on adsorption of chromium(VI)
by the coconut coir activated carbon showed that the
extent of chromium(VI) adsorption was dependent on
chromium(VI) concentration, contact time, pH and
activated carbon dose. Maximum adsorption occurred
at pH 1.0–2.0 and equilibrium adsorption
was attained in 2.5 h. Chromium(VI) adsorption
followed pseudo second-order kinetics. Equilibrium
chromium(VI) adsorption data for the coconut coir
activated carbon and the commercial activated
carbon were described by the Langmuir and
Freundlich isotherm models and indicated higher
chromium(VI) adsorption capacity of the coconut
coir activated carbon. Chromium(VI) adsorption
capacity of the coconut coir activated carbon was
compared with that of activated carbon prepared
from different waste material and bituminous coal.