Modelling of the conversion of weak organic acids by bipolar membrane electrodialysis

Organic acids are increasingly used for various industrial applications. Their production is mainly achieved by fermentation. Precipitation or extraction stages, which generates big amount of effluents, are then traditionally used to get the acid in a suitable form. Bipolar membrane electrodialysis (EDBM) can be used to achieve the conversion of the acid salt into its acidic form. Its introduction in replacement of precipitation can significantly lower the environmental impact of the process. This paper is focused on the modelling of the conversion of weak organic acid salts by EDBM The different mass transfer phenomena involved in the system are first identified. A model is then established to get expressions providing the evolution of the product and effluent lines with respect to the operating conditions. The physical meaning of the characteristic parameters involved in the model is also discussed.

This paper was devoted to the modelling of the conversion of weak organic acids by EDBM. The different transport phenomena involved in the system, i.e. a two compartment configuration using in alternance bipolar and cation exchange membranes, were studied. These were considered to establish a set of equations, the mathematical resolution of which was then carried out. Expressions were thus obtained providing the variations of the composition of the fluids, i.e. both product line and effluent line, during the EDBM conversion. These expressions require the knowledge of three characteristic parameters, the physical meaning of which was discussed. This will be checked by comparing the results calculated by the model with experimental ones obtained during the conversion of different kinds of organic acids.