| Hydrogen production by photosynthetic bacteria is an important way to recycle straw-based biomass for energy utilizations.In order to promote hydrogen production efficiency,it has been trend a new area by adding additives to the reaction system in recent years.Metal nanoparticles and carbon nanoparticles were usually chosen as the adding additives among the studies.However,Metal nanoparticles are expensive,therefore,Basalt fiber were used as the additives to investigate the effects and mechanism of the additives concentrations and granularity on the hydrogen production by photosynthetic bacteria(HAU-M1)using corn straw.Firstly,a single factor experiment was conducted to explore the effects of the addition amount and particle size of basalt fiber particles on the hydrogen production and obtain the optimal addition condition.Based on the optimal addition conditions,the mechanism of promoting photosynthetic hydrogen production by basalt fiber addition was studied.The main conclusions were listed as follows:(1)Basalt fiber can significantly promote the production of hydrogen.With the increase of addition amount,the promotion effect firstly increased and then decreased.with the addition of 1.5 g/L,the effect of promoting hydrogen production was most obvious.The cumulative hydrogen production reached to 312.42 m L,which was 15.74% higher compared with the control group.Corn straw conversion rate was 5.04%,and the maximum rate of hydrogen production was 0.28 m L/h higher than the control group.The influence of the amount of basalt fiber on the liquid phase was as follows.Basalt fiber can stabilize the p H value of the fermentation broth.The liquid products of fermentation were mainly composed of ethanol,acetic acid,propionic acid and n-butyric acid.When more than 1 g/L basalt fiber was added,there was no acetic acid in the liquid product at the end of fermentation.When the addition amount of basalt fiber was 1.5 g/L,the content of ethanol was up to 0.49 g/L,which was 53.14% higher than the control group,indicating that when basalt fiber promoted hydrogen production,the production amount of ethanol was increased.Basalt fiber can promote the conversion of straw into reducing sugar.when the addition amount was 1.5g/L,the content of reducing sugar was 1.71 g/L at 12 h,which was 22.15% higher than the control group,which was conducive to the production of hydrogen by photosynthetic bacteria.(2)The effects of the particle sizes of basalt fiber on the hydrogen production were concluded as the following: with the increase of particle sizes,the promoting effect on hydrogen production increased firstly and then decreased.When the addictive concentration and mesh number of basalt fiber were 1.5 g/L and 300~400,the reducing sugar content reached to 1.82 g/L at 12 h,which was 30% higher than the blank group.Meanwhile,the maximum cumulative amount of hydrogen production was 323.94 m L under the best addition condition,which was 18.35% higher compared to that of the control group.The highest hydrogen production rate was increased by 0.29 m L/h,and Corn straw conversion rate was 5.23%.the most significant effect on hydrogen production was achieved.Under optimal conditions,the highest concentration of ethanol was 0.47 g/L,an increase of 47.07% compared with the control group.(3)The kinetic analysis results showed that the lag phase time was increased to 21.38 h.However,The maximum hydrogen production potential was increased by 14.61% with addition of basalt fiber.(4)Basalt fiber can enhance the concentration of photosynthetic bacteria and increase the relative crystallinity of corn stalk after fermentation.When adding 1.5 g/L basalt fiber of 300 ~ 400 mesh,the bacterial concentration was 1.47 g/L at 72 h,which increased by 45.89% compared with the control group.The XRD analysis showed that the crystallinity of the corn stalk after fermentation was increased by 2.61% with addition of basalt fiber compared to that of the control group. |
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