Electrodialytic whey demineralization involving polymer-inorganic membranes, anion exchange resin and graphene-containing composite

Abstract

Electrodialysis of cheese whey was performed using polymer membranes modified with zirconium hydrophosphate (cation exchange separator) and hydrated zirconium dioxide (anion exchange material). Both neutral and acidic solutions were used as a concentrate. As found, a 0.1 M HCl solution is preferable: the current efficiency towards mineral components and desalination degree reach 75-81 % and 90 % respectively, when the current does not exceed limiting current for cations. Anion exchange resin, as well as the composite containing zirconium dioxide and oxidized graphene, were involved in desalination. The composite adsorbs preferably cations, adsorption of anions is depressed. Its adsorption capacity is 1.2 (K+) and 0.25 (CL-) mmol g-1. Whey passed subsequently through the electrodialysis cell and beds of these materials. This approach allowed us to achieve the demineralization degree of 99%, and minimize losses of organic substances. Adsorption materials can be used repeatedly. The advantage of the composite over ion exchange resins is facile regeneration.

Keywords

• electrodialysis
• cheese whey
• ion exchange membrane
• hydrated zirconiumdioxide
• graphene oxide