Effect of temperature on sorption equilibrium and sorption kinetics of organic micropollutants - a review

Temperature is an important parameter that can influence the equilibria and rates of environmental processes. In the present paper, a review of the influence of temperature on sorption equilibrium and sorption kinetics for organic micropollutants is presented. A fast and a slow process can be distinguished for sorption. For most compounds, equilibrium sorption decreases with increasing temperature. Some examples of increasing equilibrium sorption with increasing temperature and of no effect of temperature on sorption equilibrium were also found. The rate of fast desorption increased with increasing temperature. Calculated activation energies for desorption were in the range of 10–50 kJ/mol. Also, examples of no influence of temperature on the rates of fast adsorption and desorption were reported. In the present paper, the slow desorption step is assumed to be a diffusion process. Literature on the effect of temperature on the diffusion of organic compounds in polymeric structures is summarized. Activation energies for diffusion in polymers average 60 kJ/mol. The reported values for the activation energy of slow desorption are comparable to those found for diffusion of organic micropollutants through organic polymers. This is an indication that diffusion causes nonequilibrium sorption effects.