Time Lag Method and D1-D8 System

If 5 = Du the diffusion is supposed to be ideal Fickian , unless there are some hidden processes, like a drift, which are not included in this simple protocol [31]. In fact, in case of the magnetic membranes the presence of a drift is almost certain. 

Having the drift and time lag values, the average diffusion coefficient can be calculated from a proper theory from which the following formula for time lag can be derived [37]. 

To understand properly air enrichment by the magnetic membranes we had to estimate the values of Aco, i.e. an equilibrium concentration of the air components (no sorption experiments have been carried out). Since Aco is not measured (in this chapter), we have to calculate it. The most realistic value of Aco can be estimated by comparing its values obtained by the different methods. 

The first method is based on the determination of the permeability coefficient  

We have to remember that the solubility coefficient for a pure EC is known. We do not know, however, its dependence on the parameters of the experiments with a magnetic field  

---