The use of low -cost, locally available, highly efficient and eco-friendly
adsorbents has been investigated as an ideal alternative to the current expensive
methods of removing dyes from wastewater. This study investigates the potential use of
activated carbon prepared from the Annona squmosa seed for the removal of malachite
green (MG) dye from simulated wastewater. The effects of different system variables,
adsorbent dosage, initial dye concentration, pH and contact time were investigated and
optimal experimental conditions were ascertained. The results showed that as the
amount of the adsorbent is increased, the percentage of dye removal increase
accordingly. Optimum pH value for dye adsorption was 7.0. Maximum dye was
sequestered within 50 min from the start of every experiment. The adsorption of
malachite green followed the pseudo-second –order rate equation and fits the Langmuir,
Freundlich, Dubinin-Radushekevich (D-R) and Tempkin equations well. The maximum
removal of MG was obtained at pH 7 as 86.11% for adsorbent dose of 0.2 g/ 50 mL and
25 mg L
-1
initial dye concentration at room temperature. Furthermore, adsorption
kinetics of MG was studied and the rate of adsorption was found to conform to pseudosecond –order kinetics with a good correlation (R
2
> 0.99) with intraparticle diffusion as
one of the rate determining steps. Activated carbon developed from the Annona squmosa
seed can be an attractive option for dye removal from diluted industrial effluents since
test reaction made on simulated dyeing wastewater showed better removal percentage of
MG.
