Kinetic and isotherm studies of Malachite green dye removal using onion peel
Abstract
The utilization of onion peel is introduced as a new absorbent for the removal of cationic dye, Green Malachite from the aqueous solution. Various parameters, including
pH (5-9), initial solution concentration (100-700 mg L-1), adsorbent dosage (2.5-20 mg),
were used to study the effects on Green Malachite biosorption. The results appeared that
the adsorption process took place well in alkaline condition with optimum pH 9. The
adsorption rate decreased when the temperature increases showing the adsorption process
is exothermic. The adsorption will see with increase in adsorbent dosage and initial dye
concentration. However the percentage of removal decreased once the amount of dosage
reaches more than 10 mg. The equilibrium data fitted better in Langmuir model, although
it also can fit into Freundlich model demonstrate that the adsorption occurs at
heterogeneous sites and multilayer biosorption. The adsorption process followed the
pseudo-first order kinetic model showing chemisorption was involved during adsorption
process.