Recovery of sodium citrate from aqueous solutions by electrodialysis

Abstract

In this work the technical feasibility of sodium citrate recovery from aqueous solutions by electrodialysis (ED) was studied batchwise to assess the effect of feed solute concentration (c o ) and electric current density (i) on the main performance parameters of this unit operation. It was firstly found to be more profitable to stop the batch recycle electrodialysis as soon as the prefixed electric current had started to decrease. In the circumstances, Faraday efficiency (Ω) was almost independent of i and slightly affected by c o , since it decreased from 0.42±0.02 at c o =50 g/L to 0.37±0.03 at C o =100 g/L. Solute recovery efficiency (η), specific energy consumption (e), and water flux (Φ wj ) in both concentrating and diluting compartments of the ED stack were found to vary in the ranges 92-75%, 0.33-0.92 kwh.kg -1 , and 0.16-0.43 kg.m -2 .h -1 , respectively, all being statistically independent of c o and functions of i. Citrate flux (Φ s ) increased with i from 0.07 to 0.20 kg.m -2 .h -1 in accordance with Faraday's law.