Elettrodiálise

Elettrodiálise is a membrane separation process that uses an electric field to separate ions from a solution. It is a technology employed in various industrial and laboratory applications, particularly in water treatment and chemical processing. The core of the process involves an electrodialysis cell, which is constructed with alternating cation-exchange membranes (CEMs) and anion-exchange membranes (AEMs). These membranes are selectively permeable to charged ions.

The electrodialysis stack consists of a series of these membranes arranged between two electrodes. When a DC electric potential is applied across the electrodes, ions in the solution migrate towards the electrodes of opposite charge. Cations (positively charged ions) move towards the cathode (negative electrode), and anions (negatively charged ions) move towards the anode (positive electrode). The selective permeability of the CEMs and AEMs allows for the separation of these ions into different streams.

For example, in a dilute stream containing dissolved salts, cations will pass through the CEMs and anions through the AEMs, concentrating the ions in an adjacent diluate stream. Conversely, the diluate stream will become depleted of ions, resulting in purified water. The efficiency of electrodialysis depends on factors such as the applied voltage, the concentration of ions, the type and properties of the membranes used, and the flow rate of the solution. Elettrodiálise is energy-efficient for removing high concentrations of salt from water, making it suitable for desalination and for recovering valuable ions from industrial wastewater.