On identifiability for chemical systems from measurable variables

Abstract

The dynamics of the composition of chemical species in reacting systems can be characterized by a set of autonomous differential equations derived from mass conservation principles and some elementary hypothesis related to chemical reactivity. These sets of ordinary differential equations (ODEs) are basically non-linear, their complexity grows as much increases the number of substances present in the reacting media and can be characterized by a set of phenomenological constants (kinetic rate constants) which contains all the relevant information about the physical system. The determination of these kinetic constants is critical for the design or control of chemical systems from a technological point of view but the non-linear nature of the ODEs implies that there are hidden correlations between the parameters which maybe can be revealed with a identifiability analysis.

Kinetic Study of Ozone Decay in Homogeneous Phosphate-Buffered Medium

“…These constants can only be determined measuring the radical concentration evolution. In other words, that means that the observed state variables are not sensitive to k 4 and k 5 (Cantó et al 2012(Cantó et al , 2014 and then, there is not effect of these constants on the macroscopic behavior of ozone depletion. This approach demonstrates that increasing the number of chemical steps in the ozone decomposition mechanism does not improve the predicted depletion of ozone concentration.…”