Influence of water hardness on removal of copper ions by ion-exchange-assisted electrodialysis

The organic ion exchangers (Dowex HCR-S, Dowex 50WX-2) and inorganic ion exchangers with phosphate functional groups (zirconium phosphates ZrP-1, ZrP-2) were studied as transport media for ion-exchange-assisted electrodialysis of diluted solutions containing Cu (II) ions. The ion-exchange and electric conductive properties of ion exchangers containing Cu(II) ions were studied. The most conductive exchangers were chosen. The adsorption data showed a high selectivity of the zirconium phosphate towards copper ions in a concentration range from 0 to 0.5 mmol. Both exchangers were tested in ion-exchange-assisted electrodialysis of a 10!2 M solution, containing copper and hardness ions in a ratio of 1:9. It was found that efficiency of removal of the Cu(II) ions was better for the inorganic ion exchanger.

Organic as well as inorganic ion exchangers can be used in purification processes of this type Adsorption of the metal cation, mmol*g!1 Apparent diffusion coefficient for Cu2+ ions in the bed of an ion exchanger, m2 s!1 Amount of the metal ions in the catholyte, mol Time, h Metal cation concentration in the bed, mol*m!3 Specific electrical conductivity, mS*m!1