The Research On Succinic Acid Production By Bipolar Membrane Electrodialysis

Succinic acid (C4H6O4) can be used in many areas such as food, chemical andpharmaceutical industries. It is often called a “green” platform chemical because itrepresents a potential building block, which can be transformed into severalcommodity and specialty chemicals. Because of the scarcity of fossil resources, highcrude oil prices, and the environmental benefit of using renewable feedstock, thefermentation technologies applied to the production of succinic acid have arisen as afeasible alternative to chemical processes. However, efforts must be done to decreaseseparation and purification processing costs (50-80%of the final cost) in bio-basedsuccinic acid production.Owing to the majority of processing costs in fermentation are accounted for theseparation and purification of the desired product, many attempts to improve andreduce separation steps have been made, but to date there is not a successfultechnology scaled up to industrial production. Despite the fact that several separationprocesses have been proposed to overcome this problem (precipitation, reactiveextraction, ion exchange resin，crystallization), none addresses the main limitingbarriers of large energy and material requirements as well as waste generation.To achieve this goal, we considered bipolar membrane electrodialysis (BMED)which is a novel electro-membrane process that follows the heart and soul ofindustrial ecology. Several studies have indicated that BMED is an economicallyapplicable process for producing organic acids, such as citric acid, lactic acid, aceticacid, gluconic acid, tartaric acid, salicylic acid. Compared with conventionalmethod-precipitation, BMED has some inherent advantages in the production of theorganic acid such as high recovery, simple operation, without notorious solid pollution,environment protecting and so on.Currently, only a limited number of studies on lab scale focused on thefeasibility of using BMED for the preparation of succinic acid from sodium succinate. So this article discusses the effect of process conditions and membrane stackconfigurations on the process parameters, the research contents and the mainconclusions are as follows:(1) Through studying recovery rate, current efficiency and energy consumption,we discussed the correlativity between technological parameters and the experimentalpocess, such as operating current, the concentration of sodium succinate. The resultsshown that the recovery rate increased and it can reach99%, the current efficiencydecreased and it is more than50%, the lowest energy consumption was5.0kWh/kg asincreasing the current. The concentration of sodium succinate had little effect onrecovery rate. And with the concentration of sodium succinate increasing, currentefficiency increased, and energy consumption droped.(2) There are secondary reaction such as competition between the ion migration,proton tunnel effect, molecular diffusion, electroosmosis. It have different resultsusing different configurations under the same condition. Three stack configurations,such as BP-A-C-BP, BP-C-BP and BP-A-BP, were considered to find the mostcost-effective configuration. These results suggested that succinic acid could bepurified in a cost-effective manner by using BMED. The voltage drop, concentration,current efficiency, and energy consumption orders of three cell configurations forsuccinic acid production were UBP-A-C-BP＞UBP-A-BP＞UBP-C-BP, CBP-C-BP＞CBP-A-C-BP＞Ｃ BP-A-BP, BP-A-C-BP＞BP-C-BP＞BP-A-BPand EBP-A-BP＞EBP-A-C-BP＞EBP-C-BP,respectively.(3) Since the performance of membranes have important effects on the removalefficiency of the bipolar membrane electrodialysis process and are closely related tothe process efficiency, two kinds of ion exchange membrane and two types of bipolarmembrane were adopted to in the process of processing. The experimental resultsshown that succinic acid recovery rate was higher, energy consumption was lower,current efficiency was higher when using bipolar membrane BPM-2. That’s because itcan avoid contamination of other ionic. And there was little difference between thetwo kinds of ion exchange membranes.