Linear and nonlinear kinetic modelling of the uptake rate of aromatic hydrocarbons in aqueous-sediment matrix

Abstract

The time-dependent adsorption data of naphthalene, anthracene and pyrene onto sandy soil fraction conducted at a constant temperature of 25°C which represents environmental condition has been investigated using linear and nonlinear kinetic modelling approaches. Experimental data were analysed using four kinetic models; pseudo-first order, pseudo-second order, intraparticle diffusion and Elovich model equations. In order to gain insights into the mechanism controlling the sorbate-sorbent system as well as to determine the best fitting model, the correlation coefficients, and standard error estimates were used for analysis. Results of the equilibrium rate constant, adsorption capacity and correlation coefficients obtained from the different kinetic models showed that the nonlinear approach had reasonably better fits to the experimental data. This was affirmed by the use of standard error estimates. Of all the nonlinear models used the pseudo-first order kinetics successfully predicted the adsorption of the contaminant solutes. Overall, the results demonstrate that linear modelling approach is not suitable for describing the uptake of these contaminant solutes onto sediment fractions being characterised by poor regression coefficients and high standard error measurements and hence not applicable to this study.