ABSTRACT

In this study, batch adsorption experiment was carried out for the removal of anionic dyes: Sunset Yellow

and Tartrazine dyes, from aqueous solutions unto a low-cost adsorbent: Activated Cassava Sievate. The

sorption process was investigated under various experimental conditions that affect sorption capacity and

percentage removal such as; pH, initial dye concentration, temperature, contact time and adsorbent dose.

The maximum adsorption of two dyes was achieved at pH 1, equilibrium was achieved after 90 mins and an

increase in adsorption capacity from 6.09 mg/g to 29.47 mg/g with an increase in initial dye concentration

from 30 mg/L to 150 mg/L for Tartrazine dye. An increase in the sorption capacity from 4.43 mg/g to 22.02

mglg with an increase in initial dye concentration from 30 mglL to 150 mg/L for Sunset Yellow dye unto

the adsorbent was also recorded. Also, a decrease in adsorption capacity from 22.49 mg/L to 20.70 mg/L

with an increase in pH from 1 to 4, for Sunset Yellow and a decrease from3l mg/L to 27.6 mg/L with an

increase in solution pH from 1 to 6, for Tartrazine dye. The equilibrium adsorption of the dyes on the

adsorbent was analyzed using equilibrium isotherm models of Langmuir, Freundlich, Temkin and Dubinin-

Radushkevick. The R2value for the Freundlich model was highest and was found to be 0.999 for Sunset

Yellow and 0.926 for Tartrazine dye. This result indicates that the Freundlich model provides the best

correlation for the sorption process of both dyes. Kinetic models such as Pseudo-First order, Pseudo-second

order, intraparticle diffusion and Liquid-Film Diffusion models were used to study the adsorption process.

The sorption data was well suited to the Pseudo-second order model for both dyes with R2value of 1 for

Sunset Yellow and R2value of 1 for Tartrazine. The K2constants gotten from the intercepts of the plots

were 0.03 5 for both dyes. The FT-JR study and SEM micrograph of the adsorbent in its natural form, show

major functional groups that act as active sites for binding of dye molecules, and highly irregular and porous

surface of the adsorbent respectively. The experimental result revealed that both Sunset Yellow and

Tartrazine dyes is considerably adsorbed on activated cassava sievate, environmental friendly and could be

an economical method of removing Sunset Yellow and Tartrazine from aqueous solutions.