Separation Based on Chemical Potential Difference Concentration Gradient

4 Separation Based on Chemical Potential Difference (Concentration Gradient) 

Separation of electrolytes based on the difference in chemical potential across the ion exchange membrane can be classified into (i) diffusion dialysis, (ii) Donnan dialysis, (iii) neutralization dialysis and (iv) up-hill transport. The natural flux of electrolytes through the membrane is low compared with that in the presence of an electrochemical potential. 

For hydrochloric acid, the adsorbed acid on the membrane increases in the presence of metal chloride because the concentration of electrolyte substantially increases therefore, the flux of the acid increases with increasing salt concentra- 

Anion exchange membrane NEOSEPTA AFN, prepared by Tokuyama Corp. at 25.0 °C, t4cid dialysis coefficient of acid [molh-1 m 2 (moll-1)] f4lt dialysis coefficient of salt [molh-1 m-2(moII-1)] t/sait/t/acd separation coefficient. 

Industrial applications of diffusion dialysis for acid recovery include recovery of acids from waste acid from surface treatment of steel and stainless steel, from alumilite treatment, from the etching process of aluminum and titanium, and in other hydrometallurgy industries. The recovery rate of acid can be controlled by changing the flow velocity of the waste solution and water in the dialyzer, in which solutions flow counter-current. For hydrochloric acid, as explained before, 

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