Iron-based Nanoparticles Enhance Anaerobic Hydrogen Production Of Ethanol-type Fermentable Bacteria

Hydrogen energy is known as the most promising clean energy in the 21st century because of its high efficiency,cleanliness,and renewable advantages.The dark fermentation hydrogen production technology with characteristics of environmental friendliness,low production cost and sustainability has broad application prospects.How to improve the hydrogen production efficiency of dark fermentation hydrogen production will be the most important research.Fe,as the most important element in the hydrogen production process of dark fermentation bacteria,can increase the amount of hydrogen production by increasing the activity of hydrogenase.This study compared the basic hydrogen production characteristics of ethanol-type fermentable bacteria Hydrogenispora ethanolica LX-B and Oligosphaera ethanolica 8KG-4^T.The focus was on investigating the addition of iron-based nanoparticles to the fermentation system to investigate its promotion effect on the hydrogen production process.The main research contents and results are as follows:?1?A method for detecting the liquid product of hydrogen production by dark fermentation was established.Using gas chromatography,optimizing relevant parameters,and adopting 1%concentration of formic acid as the adsorption occupant,solved the problem of VFAs residues,as well as the problems of easy dissociation of each component acid and unstable induction value.The results of measurement under this condition were separated The effect is good,the standard deviation is small,the method precision is high,and the recovery rate is good.This method can also accurately and quickly determine VFAs in other anaerobic fermentation broths.?2?The hydrogen production characteristics of H.ethanolica LX-B and O.ethanolica 8KG-4^T were compared.The study found that H.ethanolica LX-B and O.ethanolica 8KG-4^T have higher hydrogen production efficiency when glucose is less than 5 g/L.When glucose is 10 g/L,the maximum hydrogen production is 17.7 mM and 21.1 mM,respectively.O.ethanolica 8KG-4^T is not tolerant to glucose higher than 30 g/L,and hydrogen production is completely inhibited,while H.ethanolica LX-B can produce 14.1 mM hydrogen even when glucose is 40 g/L.The adjustment of pH during hydrogen production has no effect on the hydrogen production of H.ethanolica LX-B,but can slightly increase the hydrogen production of O.ethanolica8KG-4^T;H.ethanolica LX-B can tolerate higher concentrations of ethanol and acetic acid,It shows that under the inhibition of high concentration products,the hydrogen production effect is still very good.yeast extract can promote the hydrogen production of two strains.When 0.05%yeast extract is added,H.ethanolica LX-B hydrogen production increases 17.8%;while the yeast extract has a weaker effect on the hydrogen production of O.ethanolica 8KG-4^T,and peptone does not promote the hydrogen production of the two strains.Compared with O.ethanolica 8KG-4^T,the H.ethanolica LX-B can produce hydrogen with a variety of sugars and has a strong hydrogen production capacity.For practical engineering applications,it has a good hydrogen production advantage and is a candidate strain with very high hydrogen production potential.?3?The promotion effect of iron-based nanoparticles on hydrogen production by H.ethanolica LX-B and O.ethanolica 8KG-4^T was mainly evaluated.The study found that both Fe₃O₄ nanoparticles and Fe₂O₃ nanoparticles can increase the hydrogen production of H.ethanolica LX-B using glucose as a fermentation substrate.The addition of 400 mg/L Fe₃O₄ nanoparticles increased the hydrogen production of the fermentation broth containing 5 g/L and 10 g/L glucose by 28.3%and 23.4%,respectively.when 300 mg/L of Fe₂O₃ nanoparticles were added,the hydrogen production of the fermentation broth containing 5 g/L and 10 g/L glucose was increased by 22.8%and 18.9%,meanwhile,the glucose utilization rate and the final pH of the fermentation broth have increased.In the study of the iron-based nanoparticles enhanced O.ethanolica 8KG-4^T hydrogen production test,it was found that the addition of 300 mg/L Fe₃O₄ nanoparticles increased the hydrogen production of the fermentation broth containing 5 g/L and 10 g/L glucose,respectively.The Fe₂O₃ nanoparticles did not promote the hydrogen production system of O.ethanolica8KG-4^T with glucose as the fermentation substrate,but the high concentration of Fe₂O₃ nanoparticles produced a significant inhibitory effect when the concentration was at 600 mg/L,the hydrogen production of the fermentation broth containing 5 g/L and 10 g/L glucose was reduced by 8.4%and 5.3%,respectively.