Study On Butanol Extractive Fermentation With Oleyl Alcohol And Recovery Product In Extraction Raffinate

The main products of butanol fermentation were acetone and butanol. The fermenting characteristic of high butanol/ low acetone was goal for people. It depended on the intracellular reducing power whether the product was acetone or butanol. The production is butanol when intracellular reducing power was strong. In traditional fermentation, 0.1%(w/v) neutral red or 10g/L sorbitol or 8mg/L nicotinic acid was added in the medium to strengthen the reducing power. It was found that compared with traditional batch fermentation the gas production per liter fermentation liquid lower by 5L, the butanol concentration increased by 18.4% and the acetone concentration decreased by 21.3% when adding 0.1%(w/v) neutral red to the medium.The solvent product of butanol fermentation, especially the main solvent product of butanol was a typical metabolic inhibition product. The extractive fermentation with oleyl alcohol could enhance the performance of butanol fermentation as it could avoid inhibition. Neutral red could partially replaced Fd to transport electron and proton. It forced Fd–red to supplement NADH by reducing NAD which strengthened the reducing power. The combination of using oleyl alcohos as extractant and adding neutral red as electron carrier could further improve the fermentation performance under the condition of using 15% corn powder medium. At the end of fermentation, the butanol concentration and the product intensity respectively increased by 45.2% and 24.5%., compared with extractive fermentation.The extractive fermentation with biodiesel as the extractant could getting improved biodiesel with butanol after fermentation, which could be used directly and leaved out the energy for collecting butanol. But in the above process, it produced a lot of extraction raffinate. If the extraction raffinate could be used to mix materials as water in next fermentation, it could economize lots of water. But there were also two problems in the treatment for extraction raffinate. One was the high butanol concentration in it which inhibited using as water to mix material in the next fermentation. The other was a lot of solvent product in unrecoverable raffinate. The cost of distillation purification could reduce greatly if the butanol involved in the extraction raffinate was recoveried with the effective extractant-oleyl alcohol which could increase the butanol concentration in oleyl alcohol. However, the extractant-oleyl alcohol is precious, although it may be recycled, its amount of use (cost) is a major problem. So the repeated extraction and multistage extraction with oleyl alcohol was studied by computer simulation, and the optimization was got. Under the condition of butanol concentration in initial extraction raffinate was10g/L, the extraction condition: the values of C1, C2, C3 in every grade respectively were 0.2, 0.2, 0.4, the general butanol concentration in oil phase was 26.33g/L, that in aqueous phase was 2.98g/L, the extraction rate was 0.70 and the total usage of oleyl alcohol was 0.8; under the condition of butanol concentration in initial extraction raffinate was 6g/L, the extraction condition: the values of C₁, C₂, C₃ in every grade respectively were 0.3, 0.3, 0.3, the general butanol concentration in oil phase was 24.93g/L, that in aqueous phase was 2.52g/L, the extraction rate was 0.75 and the total usage of oleyl alcohol was 0.9.