A simple kinetic model has been developed to explain the external mass transport of the basic dyestuffs (Basic Blue 69 and Basic Red 22) from aqueous solutions onto maize cob. The model enables the external mass-transfer coefficients, KS, to be determined and these are characteristic of the rate of mass transport of dye across the boundary layer surrounding the adsorbent particle. The external mass-transfer coefficient has been found to vary linearly with agitation, initial dye concentration, particle size range and mass of maize cob, according to the general equation KS = X(variable)Y.
