Archives of Current Research International

Certain adsorptive mechanisms and interactions often exist within linearized kinetic functions which are largely unreported. A novel inverse saturation modeling was applied to evaluate the adsorptive behavior of super-saturation, saturation, and desorptive processes on linear kinetic function plots using pseudo 1^st order, pseudo 2^nd order, Elovich and Intra-particle diffusion. Graphene oxide was prepared by room temperature synthesis and used as adsorbent over Cd²⁺ adsorbate. Batch adsorption process was conducted and four error functions were utilized. The sum of squares of the errors and Sum of absolute errors identified pseudo 2^nd order as having the least deviation at 0.113 and 0.337 respectively. The modelled pseudo 1st order reaction had R² = 0.985 while the inverse saturation model had R² value of 0.998, both been a better data fit than non-modelled pseudo 1st order R² at 0.917. The slower reaction kinetics in pseudo 1^st order was due to super-saturation during adsorption as shown by inverse saturation point. The correlation coefficient of modeled kinetic plot of pseudo 2^nd order, Intra particle diffusion and Elovich had R² = 1. The Elovich inverse saturation plot showed that the graph was an L-isotherm type indicating progressive saturation. The rate determining step experienced by Intra-particle diffusion was accommodated by wide range of inverse saturation plots showing adsorption, supersaturation and desorption as points of greatest influence. The inverse saturation plot of pseudo 2^nd order plot had absolute slope of 2.656 and large intercept of 24.815 driving it's faster reaction kinetics. Hence, the inverse saturation point modelling provided a much better interpretation of adsorptive behavior of graphene oxide adsorbent over Cd²⁺ adsorbate.