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This work is devoted to assessment of the possibility of using ceramic membranes, which contain an ion-exchange component, such as hydrated zirconium dioxide (HZD), for Cr(VI) removal from dilute solutions by electrodialysis. Transport properties of the membranes were investigated. HZD-containing membranes were found to be permeable to anions in acidic media while they demonstrate cation-exchange properties in alkaline media. Cr(VI) anion transport through HZD membranes was studied. It was shown that an increase in the amount of ion-exchanger in the membrane results in a rise in electrodialysis efficiency. The transport number of Cr(VI) species was found to range from 0.33 to 0.63 for currents below the limiting current. It was also shown that increasing the concentration of H + or Cr(VI) ions in the solution to be purified allows higher rate of Cr(VI) ion transport through the membrane. List of symbols a activity (mol m )3 ) A area (m 2 ) C Cr,s concentration of Cr(VI) in the bulk of solution (mol m )3 ) C Cr,s 0 concentration of Cr(VI) in the solution at themembrane surface (mol m )3 ) D Cr,s Cr(VI) diffusion coefficient in the solution (m 2 s )1 ) d distance between the membrane and cathode (m) E cell voltage (V) E m membrane potential (V) F Faraday constant (96485 A s mol )1 ) i membrane current density calculated with allowance for the outersurface area (A m )2 ) i Cr,lim limiting membrane current density caused by transport of Cr(VI) ions (A m )2 ) k Cr mass transport coefficient of Cr(VI) ions (m s )1 ) L membrane length (m) N Cr,m flux of Cr(VI) ions through the membrane (mol m )2 s )1 ) N Na,m flux of Na + ions through the membrane (mol m )2 s )1 ) n Cr,a amount of Cr(VI) ions in the anolyte (mol) n Na,c amount of Na + ions in the catholyte (mol) R gas constant (8.314 J mol )1 K )1 ) T temperature (K) t Cr,m transport number of Cr(VI) ions through the membrane (dimensionless) t Cr,s transport number of Cr(VI) ions through the solution (dimensionless) u superficial flow rate (for the cathode compartment) (m s )1 ) z charge of species (dimensionless) Greeks c ratio of anion over cation valences (dimensionless) j specific conductivity (Ohm )1 m )1 ) s time (s, h) m kinematic viscosity (m 2 s )1 ) Dimensionless Groups ReReynolds number

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