Electrodialysis in Hydrometallurgical Processes

Abstract

Electrodialysis (ED) is an ionic exchange membrane process for separation of different components and species. In desalination a large part of the energy is used to sustain a concentration difference between the solutions, but in the processes of exchanging in selective manners, the energy need is lower and more directed towards ohmic losses in the membranes. The latter has relevance to several hydrometallurgical industries, as they very often accumulate undesired species in their process streams and currently apply intensive (energy and chemical) routes to remove these species. Here, we describe the principle of ED and discuss opportunities for component and salt separation using ion exchange membranes by providing a brief review of ED in the hydrometallurgical sector.

Cation Exchange Membranes and Process Optimizations in Electrodialysis for Selective Metal Separation: A Review

“…In summary, the selectivity for Cation 1 over Cation 2 increases when the current density is bigger than the specific limiting current density for Cation 2. This process-related selectivity mechanism is referred to as the boundary layer separation [ 5 ]. It is applicable when the target species of the separation process has a significantly different concentration from competing counter-ions in the solution.…”

“…Cation exchange membranes (CEMs), on the other hand, are separation membranes that continue attracting considerable attention to treat metal-contaminated water, particularly in technologies involving electrodialysis [ 5 ]. Electrodialysis can offer numerous advantages compared to conventional technologies, such as excellent selective recovery, treatment of dilute concentrations of targeted ions, and a more environmentally friendly operation [ 6 , 7 ].…”

Enhancing Palladium Recovery Rates in Industrial Residual Solutions through Electrodialysis

“…Thereby, ions accumulate in the concentrate compartment, while the diluate compartment is depleted of ions. The permselectivity determines the degree to which the IEMs selectively allow ions of opposite charge (counter-ions) to permeate while repelling ions of like charge (co-ions) [32]. Apart from their charge, the hydration energy of ions can be used to control their permeability.…”

Limiting Current Density as a Selectivity Factor in Electrodialysis of Multi-Ionic Mixtures

“…Applying an electric potential across the cell establishes a charge imbalance in the stack, forcing cations towards the cathode, passing the CEM, and anions towards the anode, passing the AEM. Consequently, anions and cations are collected in every second compartment while every other compartment is desalinated [4]. The ions preferably transported across the membrane are called counter-ions, and the ions repelled by the membrane are called co-ions.…”