Composite inorganic anion exchange membrane for electrodialytic desalination of milky whey

Abstract Composite membranes have been obtained by modification of macroporous ceramics with hydrated zirconium dioxide and basic bismuth nitrate. The modification technique provided formation of the two-component modifier directly in macropores of the inorganic matrix. This method allows us to obtain the material, which possesses by optimal combination of charge selectivity and electrical conductivity, by means of one-time modification. It is assumed that nanoparticles of basic bismuth nitrate (5 nm) block pores between larger particles of hydrated zirconium dioxide (several tens of nanometers) providing semipermeability of the membranes towards anions in acidic media: potentiometric transport number of counter-ions (Cl - ) reaches 0.9. Electrodialytic desalination of milky whey has been carried out using a pair of polymer cation exchange (Nafion 117) and composite inorganic membranes. The possibility of whey desalination under overlimiting current has been shown. The current efficiency due to anions reaches 80% under these conditions. Electrodialysis of whey allows us to remove 75 % of the mineral components in 3 h, the same purification degree is achieved in 30 min for nanofiltration permeate.