Adsorption Equilibria of Basic Dyestuffs onto Maize Cob

Equilibrium isotherms have been determined for the adsorption of basic dyestuffs, namely, Basic Blue 69 (BB 69) and Basic Red 22 (BR 22), onto maize cob. The experimental results have been fitted with Langmuir, Freundlich and Redlich–Peterson isotherms. The maximum adsorption capacity of the maize cob was found to be 160 mg dye per g maize cob for BB 69 and 94.5 mg dye per g maize cob for BR 22. The relative costs of dye removal are reported based on adsorption capacity only; the cost of removal of BB 69 and BR 22 using maize cob was only 4.1% and 8.3%, respectively, that of activated carbon.