Ion-Exchang Purificatioon of Alpha-Ketoglutaric Acid in Fermentation Broth

In order to purify α-ketoglutarate acid from fermentation broth,the purification technology of α-ketoglutarate acid by ion-exchange method was studied after decolored by activated carbon.The results showed as follows. Firstly,the decolorization ratio reached 89.2% under the following optimal conditions:carbon dosage 1.5 g/L,pH 3,bleaching time 1 h,bleaching temperature50 ℃. Subsequently,the process of ion-exchange was studied and among 6 different resins D301weakly-based anion resin was the optimal one for α-ketoglutaric acid abstraction by comparison of the adsorption capacity. And the optimal absorption efficiency was achieved when the α-ketoglutarate acid concentration in the fermentation broth was 20 g/L,the sample flow rate was 2.67BV/h and the diameter to height ratio was 1 ∶12. Finally,a process of stepwise elution wasinvestigated. In the first step,0.01 mol/L NaCl and 0.01 mol/L HCl mixed solution was used as eluent and in the second step,0.3 mol/L HCl was used as eluent and the flow rate was 6 BV/h.With the elution strategy above,the final yield of α-ketoglutaric acid reached 93.2% and an excellent purification result was achieved with the increased mass ratio of α-ketoglutaric acid to pyruvic acid from 1.5∶1 to 10∶1. Therefore,ion-exchange method was valid to purify α-ketoglutaric acid from fermatation borth.