Effects of phytogenic copper nanoparticles on fermentative hydrogen production by Enterobacter cloacae and Clostridium acetobutylicum

• Phytogenic CuNPs inhibited the anaerobic fermentation process using pure strains.
• The inhibitory model was analyzed by modified Han–Levenspiel model.
• Inhibitory effect of CuNPs on E. cloacae and C. acetobutylicum was high than the Cu2+.
• Cu2+ and CuNPs influenced the negative effects on acetate/butyrate fermentation type.

Copper nanoparticles (Cu-NPs) were synthesized using Murraya koenigii leaf extract as reducing agent and characterized. TEM images show that the Cu-NPs were mostly cuboid shaped with an average size of about 97 nm. The influence of phytogenic Cu-NPs on biohydrogen production from glucose was studied using Enterobacter cloacae and Clostridium acetobutylicum, and its effects were compared with CuSO4. The effects of Cu-NPs and CuSO4 (2.5, 5.0, 7.5, 10.0 and 12.5 mg/L) on biohydrogen production using E. cloacae at pH 7.0 and C. acetobutylicum at pH 6.0 were performed in batch mode. Both Cu-NPs and CuSO4 supplementation inhibited the biohydrogen production in a dose dependent manner. The Cu-NPs were found to have more inhibitory effect on biohydrogen production of E. cloacae and C. acetobutylicum than CuSO4.

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