دانلود رایگان مقاله بازیابی بیوبوتانول از مدل راه حل / تخمیر براث با تریپتاسیم فسفات

ABSTRACT

The acetone + 1-butanol + ethanol (ABE) fermentation has a long history but still faces the challenge of enhancing the low ABE concentration to reduce production cost. Nowadays there is an unprecedented resurgence of interest in separation and purification technology to recovery ABE from fermentation broth. Here we describe a simple salting out procedure for extracting ABE fermentation products efficiently from model solutions/fermentation broth by employing tripotassium phosphate (K3PO4). Increasing the K3PO4 content permits the liquid-liquid splits and enables the recovery of ABE. The liquid-liquid equilibria were mainly determined by the K3PO4 content and slightly affected by temperature and original solvents level. The correlation between the solubility of ABE and the molality of K3PO4 demonstrated this. More than 90 wt% of ABE was recovered from the model solutions/fermentation broth and more than 99.75% of water was removed. This study provides a means to reduce the energy demand of the subsequent distillation process for ABE purification.

4. Conclusions

Using this salting-out of acetone, 1-butanol and ethanol induced byK3PO4, wedevelopedahigh-enrichmentmethodfordilute aqueous ABE solutions (ABE in water). By gradually increasing the K3PO4 concentration we are able to obtain higher distribution coefficients of ABE and achieve higher ABE contents of the organic phase. The effect of temperature was very small except at the highest initial concentration. The water content of the organic phase below 10 wt% meant that most of the water from the model solution was removed. 1-butanol was recovered preferentially and achieved total recovery at a lower salting-outfactor.When theK3PO4 solution was twice model solution/fermentation broth, more than 90 wt% of ABE could be recovered and more than 99.75% of water was removed. A higher level of ethanol made the organic phase more hydrophilic, resulting in a higher water content of the organic phase and the lower dehydration ratio. A higher solvents level contributes to the higher recovery of ABE. The difference in the composition betweenmodel solutionsA &B had a significant effect on the compositions of the aqueous phases. However, there is a linear relation between logarithm of the solubility of ABE and the molality of K3PO4 in the aqueous phase. The salting-out effect of the K3PO4 solution on the model solutions/fermentation broth was mainly determined by the molality of K3PO4. The energy and ecological problem associated with the saltingout method is the salt recovery. Future work will concentrate on the improvements in the salt recovery from the aqueous phase, and the design of downstream distillation unit for the ABE purifi- cation. The evaporation may be involved in the salt recovery from the aqueous phase if the fermentation broth is pretreated by a prefractionator [26]. But it was impractical in terms of the bulk aqueous phase in this study. Therefore, other alternatives such as the breakthrough of the membrane science to the enrichment of the concentrated salt solution should be exploited to make the salt recoverymore energy-saving.Withthe salt recovery fromthe aqueous phase solved, the new design of the downstream distillation unit for the purifications of ABE will be more accessible to the plant operation.