Investigating the effects of iron and nickel nanoparticles on dark hydrogen fermentation from starch using central composite design

• Dark hydrogen fermentation from starch was performed using mesophilic sludge.
• Effects of iron and nickel nanoparticles on biohydrogen production were studied.
• Response surface method was used to design the experiments and analyse the results.
• Yield of 149.6 mL H2/g-VS was obtained by adding 37.5 mg/L of each nanoparticle.

The effects of Fe0 and Ni0 nanoparticles on mesophilic dark hydrogen fermentation from starch were investigated using heat-shock pretreated anaerobic sludge in batch reactors. Starch concentration in the range of 0–20 g/L was used in the presence of 0–50 mg/L of each Fe0 and Ni0 nanoparticles while the initial pH of all experiments was adjusted to 7. The hydrogen production was optimized using response surface methodology (RSM) in a central composite design (CCD) mode. The results showed the significance of the linear effect of starch and Fe0 concentrations, the interactive effect between Fe0 and Ni0 concentrations, and the squared effect of starch concentration on the biohydrogen production. The maximum yield of hydrogen production 149.8 mL/g-VS was obtained at starch, Fe0 and Ni0 concentrations of 5.37 g/L, 37.5 mg/L, and 37.5 mg/L, respectively. This was nearly 200% higher than those in the corresponding control test. Moreover, the analysis of metabolites indicated the hydrogen production through acetic acid pathway.