Continuous dialysis of selected salts of sulphuric acid

The transport of selected salts of sulphuric acid (cobalt, copper, iron(II), manganese, nickel and zinc sulphate) through an anion-exchange membrane Neosepta-AFN was investigated in a counter-current continuous dialyzer at various salt concentrations and volumetric liquid flow rates. The basic transport characteristics - the rejection coefficient of salt and the permeability of the membrane - were calculated from measurements at steady state. The salt concentration in model mixtures was changed in the limits from 0.1 to 1.0 kmol m(-3) and the volumetric liquid flow rate of the inlet streams was in the limits from 8x10(-9) to 24x10(-9) m(3) s(-1). Under the experimental conditions given, the rejection coefficient of salts tested was in the range from 65% to 94%. The lowest values were obtained for iron(II) sulphate, while the highest for copper sulphate. The maximum rejection of salt was reached at the highest volumetric liquid flow rate and the highest salt concentration in the feed. The permeability (P-A) of the Neosepta-AFN membrane for the individual salts was in the range from 0.49x10(-7) m s(-1) to 1.8x10(-7) m s(-1) and it can be described by the following series: P-FeSO4<P-NiSO4<P-ZnSO4<P-CoSO4<P-MnSO4<P-CuSO4. The permeability of the membrane was strongly affected by the salt concentration in the feed - it decreased with an increasing salt concentration.