Coupled Kinetics Adsorption–Desorption Model Applied to Batch Tests

Abstract

Batch tests are extensively used in a wide range of fields, including environmental engineering, to forecast the impact of sorption on contaminant transportation in soil and wastewater treatment effectiveness. Recently, batch tests have been utilized to assess sorption kinetics, which was previously considered an instantaneous process. In this study, an analytical solution is proposed to the pseudosecond-order equation for sorption kinetics in batch tests, which considers the initial concentration in both the solution and sorbent material, such as soil. First, a parametric study was conducted to comprehend the effect of model fitting parameters and the initial conditions of the test on the results. Following this, experimental validation was carried out by applying the kinetic adsorption–desorption model to existing literature results. The calibration process involved three fitting parameters that were physically significant and independent of the initial concentration conditions. The main advantage of this model is that it uses the same fitting parameters to predict sorption equilibrium and sorption kinetics under different initial conditions. The calibrated model enabled the estimation of the adsorbed solute for any initial concentrations and provided a physical interpretation of the results for different contact times and initial concentrations.