Improving mechanisms of biohydrogen production from grass using zero-valent iron nanoparticles.

This paper investigated the improving mechanisms and microbial community dynamics of using zero-valent iron nanoparticles (Fe0 NPs) in hydrogen fermentation of grass. Results showed that Fe0 NPs supplement improved microbial activity and changed dominant microbial communities from Enterobacter sp. to Clostridium sp., which induced a more efficient metabolic pathway towards higher hydrogen production. Meanwhile, it is also proposed that Fe0 NPs could accelerate electron transfer between ferredoxin and hydrogenase, and promote the activity of key enzymes by the released Fe2+ . The maximal hydrogen yield and hydrogen production rate were 64.7 mL/g-dry grass and 12.1 mL/h, respectively at Fe0 NPs dosage of 400 mg/L, which were 73.1% and 128.3% higher compared with the control group. Fe0 NPs also shorten the lag time and facilitated the hydrolysis and utilization of grass. This study demonstrated that Fe0 NPs could effectively improve hydrogen production and accelerate the fermentation process of grass.