Coconut Coir Activated Carbon: An Adsorbent for Removal of Textile Acid Azo Dye from Aqueous Solution

The objective of the study is to prepare an adsorbent
from an agricultural waste and assess its effectiveness in
removing textile acid azo dye from aqueous solution. Activated
carbon was prepared from coconut coir and characterized.
Adsorption of two textile acid azo dyes, Acid Red 18 and Acid
Orange 7, by the activated carbon was examined by batch
adsorption test. Extent of dye adsorption depended on contact
time, pH and carbon dose. Equilibrium adsorption was attained
in 2 h and maximum adsorption occurred at pH 3. Equilibrium
adsorption data of the acid azo dyes by coconut coir activated
carbon and a coal-based commercial activated carbon conformed
to the Langmuir and Freundlich adsorption isotherm models.
According to Freundlich isotherm, adsorption capacity of the
coconut coir activated carbon for the acid azo dyes is higher
compared to that of the commercial activated carbon, whereas
according to Langmuir adsorption isotherm, the coconut coir
activated carbon has 76-81% of the adsorption capacity of the
commercial activated carbon. Coconut coir activated carbon is a
low-cost substitute for commercial activated carbon in the
removal of acid azo dyes from aqueous solution and textile dye
waste.