Investigation of Kinetics of Adsorption of Acidic Blue 206 Dye on Multi-Wall Carbon Nano Tube Using Linear and Nonlinear Regression and Activation Energy Determination

In this research, the kinetics of removal of acidic blue 206, an acidic dye, from aqueous solution by multi-wall carbon nanotube at optimized pH of 6.5 and 298K has been investigated. Six kinetics models contain pseudo-first-order, pseudo-second-order, intra-particle, Elovich, Bingham, and modified Freundlich model used. Kinetic data were fitted by these six models using linear and nonlinear regression. The results showed that the pseudo-second-order model was best fitted in both linear and nonlinear regression methods. The rate-determining step was the surface adsorption. The calculated qe at pseudo-first-order and pseudo-second-order models, (73mg/g and 75mg/g, respectively) are near the experimental value (99 mg/g). The order of compatibility of data with other models at nonlinear regression is pseudo-first order> Bingham> modified Freundlich> Elovich> intra-particle diffusion models. For leaner regression the order of compatibility of data are Bingham> elovich> modified freundlich> intra-particle diffusion> pseudo-first-order models. The calculated Arrhenius activation energy was -61.63kJ/mol. The negative activation energy, Ea, means that there is no barrier energy on surface adsorption and the adsorption is exothermic.