Theoretical analysis of neutralization dialysis in the three-compartment membrane cell

Capacitive neutralization deionization with flow electrodes

“…14. However, since proton ions diffuse faster than hydroxyls [25], the pH value in the water channel for ND and FCND increases in a short time after the electrical potential is applied, and then decreases quickly in the water channel, forming an acidic condition, as shown in Fig. 5.…”

“…ND [24] is a membrane desalination process which is based on the simultaneous use of two Donnan dialysis operations, one against the acidic and the other against alkaline solution with cation-and anion-exchange membranes, respectively. Driven by the Donnan potential formed by the salt concentration difference across the membrane, the H + and OH -penetrating into the salt water compartment in exchange for salt ions annihilate in the neutralization reaction [25,26]. Through this process, salt water is traded for clean water.…”

Neutralization Dialysis for Phenylalanine and Mineral Salt Separation. Simple Theory and Experiment

“…A periodic increase and decrease in pH into the desalination compartment was experimentally confirmed in [33,34,38]. Models [36,37] were improved in [39], where a batch mode of the ND is considered. This model includes such parameters as IEM exchange capacity, electric conductivity and diffusion layer thicknesses found from the independent experiments.…”

“…This model includes such parameters as IEM exchange capacity, electric conductivity and diffusion layer thicknesses found from the independent experiments. Calculations using this non-steady state model showed that fluctuations in pH and electric conductivity at the initial stages of ND could not be described within the framework of the quasi-steady state model [37]. At the same time, both models give the same results in 20-30 min from the beginning of ND after stationary concentration profiles are formed into the membranes.…”

“…The numerical solution of these equations made it possible to evaluate quantitatively the influence of the Reynolds numbers and the feeding solution pH upon the average dialysis rates of each of the ions participating in ND process. A similar quasi-steady state model describing the ND kinetics was developed by Denisov et al [37]. The transport of ions through ideally selective IEMs and DBLs are taken into account in the model.…”