Co-extraction And Separation Of Propionic Acid And Succinic Acid By Ion Exchange Method

Propionic acid production by microbial fermentation has attracted more and more attention,but people focus on how to remove product feedback inhibition and improve the substrate conversion rate.The extraction and separation of propionic acid from the fermentation liquid is seldom reported.In this paper,the technological parameters of separation of propionic acid and succinic acid from the fermentation liquid of propionibacterium freudenreichii with ZGD630 resin were analyzed in detail.A "two stage" chromatography technology for the separation of propionic acid and succinic acid was established,and the scale-up technology was also completed.The main results of this paper were as follows:(1)The process parameters of separation of propionic acid from the fermentation liquid with ZGD630 resin were investigated.The adsorption conditions were optimized to improve the ZGD630 resin adsorption capacity of propionic acid,succinic acid,and acetic acid.The results showed that the ZGD630 resin static adsorption of propionic acid and succinic acid were 89.4 mg/g and 108.2 mg/g after acidification to pH 1.5,increased by 101.35% and71.74%,compared to the initial fermentation liquid(pH 6.8).(2)The dynamic adsorption process of propionic acid,succinic acid and acetic acid from the acidified fermentation liquid with ZGD630 anion exchange resin was investigated.The results showed that succinic acid was adsorbed preferentially by ZGD630 resin when excess loaded onto the column.Propionic acid began to be absorbed only when succinic acid was completely adsorbed.Thus,the permeate liquid included three portions: 0-2 BV,withnot succinic acid,propionic acid;2-6.5 BV,withnot succinic acid,but containing propionic acid;>6.5 BV,containing succinic acid,propionic acid(BV refers to the volume of resin).(3)In this paper,the technology of "two stage" chromatography for the production of propionic acid and succinic acid was established,and the operating parameters were determined.Results show,firstly,the succinic acid in fermentation broth was adsorbed by column chromatography?.The optimal sample flow rate was 3 BV/h and the sample volume was 10 BV.The succinic acid could be completely inserted into the column?.Then,the flow of the chromatography column ?(not containing succinic acid)on the sample to the column chromatography ?,the sample flow rate was 3 BV/h and the sample volume was 5 BV,to ensure that the adsorption saturation.(4)Chromatography column ? was eluted by NaOH.Results showed that the optimum elution concentration of NaOH was 3 mol/L and the elution flow rate was 0.45 BV/h.The highest concentration of succinic acid could reach 91.28 g/L,which is about 7.1 times the concentration of succinic acid in fermentation broth.Chromatography column ? was eluted by H2SO4.Results showed that the optimum elution concentration of H2SO4 was 4 mol/L,the elution flow rate was 0.6 BV/h,the highest concentration of propionic acid was 97.02 g/L,which was about 4.4 times the concentration of propionic acid in the fermentation broth.(5)The amplification experiment of 10 L column was carried out,and good results were obtained.The recovery of propionic acid and succinic acid reached 88.12% and 91.05%.