Separation And Modeling Of Succinic Acid Simulated Fermentation Broth By Nanofiltration

The purpose of this article is to find a viable membrane separation and concentration method to separate the succinic acid from other substances in fermentation broth,in order to meet industrial production needs of the value chain from fermentation broth to succinic acid to y-butyrolactone.First,retention experiments of succinic acid solution are conducted,in which the effect of pressure,pH,temperature and other variables on the succinic acid retention and flux are considered.Then the appropriate mathematical models are found for different pressure conditions and pH conditions,verifing the optimal conditions in the experiment with computer simulation.Finally,nanofiltation membrane is used to separate succinic acid simulated fermentation broth and find the difference between two solutions.The main contents are as followed.Study on retention experiments of succinic acid solution.The results show that when the pH is 5.5,the pressure is 1.5MPa and the temperature is 20℃,the retention speed is the highest with 614.73 g/(h·-m2),the retention rate is 74.36%,and the flux is 34.44 L/(h·m2).Investigation of pressure on succinic acid retention.Based on the Solution-diffusion model(SDM)and considering the effect of concentration polarization,the Modified solution-diffusion model(MSDM)is proposed.The absolute errors of SDM and MSDM are controlled within±2.5%with the relative errors within ±5%.According to the model,the maximum retention speed of MSDM is 608.89 g/(h.·m2)with the pressure of 1.5 MPa and the concentration of 24 g/L.Exploration of pH on succinic acid retention.The Electrostatic and steric-hindrance model is built.The absolute errors of this model are controlled within ± 1.5%with the relative errors within ± 2.5%.According to the model,the maximum retention speed of the model is 419.89 g/(h·m2)with the pH of 5.44.Selective separation of succinic acid and glucose is achieved when pH is the initial pH,the yield of succinic acid is 91.1%,the retention rate of acetic acid is 1.8%,and the retention rate of glucose is 86.6%.The acetic acid and succinic acid with nanofiltraion membrane can be separated when the pH of permeate is changed to 5.5.After concentration by nanofiltration,the concentration of succinic acid is 27.48 g/L,the yield of succinic acid is 75.1%,the retention rate of acetic acid is 91.5%,the retention rate of glucose is 90.9%,and the flux is 32.89 L/(h·m2).The mass ratio of succinic acid to acetic acid and succinic acid to glucose are increased by 8.88 times and 8.21 times respectively than before.The results show that the use of nanofiltration selective separation of succinic acid is feasible.