| Nowadays with the energy crisis and environmental problem growing worse, it becomes very imperative to develop more new renewable resources. Butanol, which has a relatively high energy and density, can play a superior role than ethanol to replace gasoline as fuel. Meanwhile, the cost will be reduced effectively by using the wood fiber to get butanol. This paper, based on the study of the effect of inhibitors in corn stover hydrolysates on butanol fermentation, explored the removal efficiencies of inhibitors and the effects on butanol fermentation by using different detoxification methods, and then built an efficient detoxification technology system. By optimizing the extractant and the extraction fermentation technique of butanol, it built a preponderant extraction fermentation technology of fiber butanol, which would provide a necessary technical support for the industrialized production of fiber butanol.Having studied on the 6 kinds of inhibitors in corn stover hydrolysates and analysised their influence on fermentation process, we could get that, with the supplementation of 1g/L, the order of factors inhibiting C. acetobutylicum CICC 8016 were coumaric acid, sodium formate, levulinic acid, furfural and 5-hydroxymethylfurfural. We also found that adding 0.5 g/L of sodium formate could cut down 78.7% of the total solvent production and with 3 g/L levulinic acid it was only 12.4%. Furfural would delay the fermentation process with its concentration of 1 g/L, and the growth of cells and production would be completely inhibited when it is 2g/L. However 5-hydroxymethylfurfural would not affect the growth and production obviously with its concentration range of 0.1 to 1 g/L. As a kind of phenolic compound, coumaric acid could promote cell growth with its concentration under 0.2 g/L. The inhibition was found with the concentration over 0.5 g/L, and the fermentation was completely stopped in 1 g/L.Comparing the following 5 detoxification methods of overliming, steam stripping, extraction, ion-exchange resin and rotary evaporation, we found that overliming, extraction, rotary evaporation and D941 resin contributed to reducing the loss rate of sugar. Steam stripping had a good performance on removing formic acid and acetic acid. So did overliming, extraction, stream stripping and rotary evaporation on removing 5-hydroxymethylfurfural, but the first two were worse to remove furfural. The anion-exchange resins had a positive effect on detoxification, and the remarkable removal rate of total phenol could be over 86.2%.It showed that butanol fermentation yield was higher than other treatments by using anion-exchange resin to detoxicate. The D301 resin was the best in all resins, as it could get a butanol production of 6.89 g/L, ABE production of 10.27 g/L, and the ABE yield is 0.36 g/g and the utilization rate of total sugars is 99.1%. Then it obtained ABE of 11.4 g/L with 6% hydrolyzed sugars.Oleyl alcohol was suitable for butanol extractive fermentation with corn stover hydrolysates by selecting optimized extractant. The optimum conditions of oleyl alcohol extractive fermentation were adding oleyl alcohol with 0 h and 1:1(v/v) into the hydrolyzed corn stover medium, the total solvent production of butanol fermentation was 4.72 g/L, over almost 9-fold with control. The maximum production of butanol was 3.28 g/L, increased 881.4%.After detoxification by D301 resin and adding oleyl alcohol, the final butanol and ABE production from the concentration of 5% hydrolyzed sugar were 10.34 g/L and 14.72 g/L.And the ABE yield was 0.31 g/g(g ABE/g utilized sugar). |
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