CONTRIBUTIONS TO THE DEVELOPMENT OF THE MATERIAL BALANCE OF MIGRATION PROCESS OF METAL IONS FROM THE AISI304 STAINLESS STEEL IN ACETIC ACID SOLUTIONS

摘要

The aim of this work was the development of theoretical and real material balance by studying the diffusion phenomena of the metallic ions from AISI304 stainless steel samples in acetic acid solutions with 3%, 6% and 9% concentrations. The correlation of the quantities of substance which migrate from the metallic alloys in the food simulants through the interaction interface between the two environments can be accomplished through the materials balance developed for each component. To development the materials balance, we used the general stoichiometric equation of a chemical process. Within the comparative study of the theoretical and real mass balance, we have used the experimental data obtained after the migration tests, where the variables were represented by the working parameters: the temperature of the migration testing - T [°C], the exposure time - t [min.] and the stirring of the corrosive environment - n [rot·min -1 ]. The value of each parameter was varied on three levels, in accordance with the real situations met in practice. In order to express the quantitative stage of the interaction between the metallic material and the corrosive environment, at a certain moment, we have used the degree of dissolution δ M of the metallic components such as Mn, Cr, 56 Fe and Ni. The comparative study of the dissolution rates obtained allows to extrapolate and to elaborate in practice the optimization of the process which occurs at the interface of the two real food environments.