Model analysis on electrodialysis for inorganic acid recovery and its experimental validation

Theoretically, conventional electrodialysis (ED) technology should have played important roles in the reclamation of acid-containing discharge. However, at present, it is seriously restricted by some unresolved problems and badly in need of deep understanding. Accordingly, the model analyses on an ED process for acid recovery are performed for a possible prediction and effective optimization in this study. Above all, the negative contributions from the electro-migration and concentration diffusion to the acid-recovery process were firstly isolated by means of a series of well-designed experiments. Results indicated that the potential gradient and concentration difference did play significant roles in the undesired transport of protons. Especially, the acid leakage is practically proportional to the corresponding driving forces, which contributes to accurately predict the corresponding negative contributions on the basis of a deep understanding on the characteristics of the acid-recovery system and ED stack configuration. Furthermore, a concentration evolution model was established, which paved a road for the subsequent calculation of process energy consumption with aid of some classical mathematical expressions and parameter measurements. Practical ED experiments showed that the simulation results were in good agreement with the experimental data, which verified the validity of the proposed model.