Comparison analysis on biohydrogen production of mesophilic and thermophilic dark fermentation using nickel doped lanthanum-iron oxide nanoparticles as supplementation

Abstract

In this work, perovskite-structured LaNi0.5Fe0.5O3 nanoparticles (NPs) are successfully synthesized to explore influence of addition amounts on biohydrogen yield. The great potential advantages to improve the biohydrogen production under mesophilic and thermophilic dark fermentation are systematically investigated by a series of experiments. The characterization of physicochemical properties of LaNi0.5Fe0.5O3 NPs are summarized and analyzed. The highest biohydrogen yield 262.55 mL/g of mesophilic dark fermentation is obtained at 100 mg/L LaNi0.5Fe0.5O3 NPs group while under thermophilic condition, the maximum of biohydrogen production is only 182.13 mL/g with 200 mg/L LaNi0.5Fe0.5O3 supplementation, which are higher 50.7% and 91.0% than that of corresponding control groups, respectively. The analysis of soluble microbial products (SMPs) suggests that LaNi0.5Fe0.5O3 NPs can observably enhance the butyrate-type metabolic pathway, being consistent with the raising abundance of Clostridium butyricum in mesophilic fermentation. The extracellular polymer content is significantly increased with appropriate addition of LaNi0.5Fe0.5O3 NPs. The results reveal that the moderate amount of LaNi0.5Fe0.5O3 NPs can even optimize the microbial community structure by increasing the abundance of Clostridium sensu stricto 1 under mesophilic fermentation and Clostridium sensu stricto 7 as well as Longonea under thermophilic fermentation. Eventually, it can be affirmatively concluded that the application of LaNi0.5Fe0.5O3 NPs to dark fermentation contributes to more biohydrogen yield with moderate amounts under both mesophilic and thermophilic conditions. The innovative work of nickel doped lanthanum-iron oxide nanoparticles provides an effective strategy to take the fully advantage of Fe and Ni element for biohydrogen yield.