Study Carried Out in a First Paper

Tedious but also sophisticated methods are described and used. The following experiments 

The kinetics of transfer of the additive through a solid-solid contact without interaction of the liquid, by using a tri-layer system with a loaded polymer sheet inserted between two virgin sheets (0.037 cm thick for each sheet). From time-to-time, the concentration of the additive is measured in the sheets. The so-called plateau, or value at equilibrium, is attained after a three month experiment using a 57 p,m thick film. 

The kinetics of transfer of the additive through the polymer pre-saturated with the solution made of the liquid (simulating the food) and additive, by immersing this pre-saturated polymer into the pure liquid. A somewhat symmetrical experiment is also made by immersing into the solution of the additive in the liquid, the presaturated polymer with the pure liquid. 

Various studies are made in this paper some are directly concerned with the problem of food pollution, but others however, are of concern as they prompt some questions. Let us consider the transfer of the additive into the liquid. 

The method of writing the equations is very cumbersome as well as the presentation of the numerical model [41]. Surely, a more simple way is based on using integers i and j, so that the following is obtained for the position of the very thin sheet in which the concentration is constant x = i. Ax, and for the time t = j. At. By using these symbols, the concentration is written as C j. 

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