Analyzing energy consumption for the electrodialysis based on separation of gluconic acid (sodium gluconate) including optimization by applying dynamic electrical potential

BACKGROUND

The energy consumption and optimization of separation processes are of great interest. Focusing on this, in the present paper, the separation of gluconic acid from a model solution using electrodialysis was investigated. The first question is which voltages (current density) should be applied. To have an orientation for the value of this parameter, one can find the maximum current efficiency (CE) and take the corresponding voltage. Because the CE decreases during the separation process when keeping either voltage or current density constant, the voltage can be adjusted so that the CE remains at maximum (dynamic voltage operation). Thus, the energy consumption can be reduced. However, the ion flux will decrease, which needs to be taken into account for economic reasons (increasing membrane area).

RESULTS

Adjusting the voltage to keep the CE at maximum or very close to maximum results in a reduction of energy consumption to ≈25% compared to constant voltage operation. The ion flux decreases to a factor of 3, which significantly increases the necessary membrane area. The results also show that when operating with higher voltages (e.g. constant voltage operation), the energy consumption can increase considerably due to decreasing CE and increasing entropy production.

CONCLUSION

From an economic point of view, it may be justified to apply higher voltages while accepting considerably higher energy consumptions. However, industrial experience is necessary to determine if there are additional negative effects. Additionally, for example, life-cycle assessment is recommended to consider sustainability requirements. © 2025 Society of Chemical Industry (SCI).