Application of a Mixed Order Model to Determine the Rate Adsorption of 1-Nitronaphthalene onto Activated Carbon

Abstract

This study investigated the adsorption kinetics of 1-nitronaphthalene solution (a polycyclic aromatic hydrocarbon, PAH) onto seven different masses of activated carbon. The coefficient of determination (r²) was used to determine the best-fit kinetic model and to confirm agreement between experimental data and the kinetic rate equations. The results indicated that adsorption could be defined with masses of 0.0200 g and 0.0501 g when fitted using a second order rate equation. Adsorption on to masses of 0.1003 g, 0.1203, 0.1501 g, and 0.2001 g was best defined when data were fitted to a pseudo second order rate equation. However, adsorption onto a mass of 0.0701 g did not fit with any simple rate law. Consequently, a new mathematical mixed order equation was developed to determine the rates of adsorption and the rate constants by combining two orders of equations: the pseudo first order and pseudo second order, to achieve a better fit with the same data.