Improving effect of metal and oxide nanoparticles encapsulated in porous silica on fermentative biohydrogen production by Clostridium butyricum

This paper investigated the enhancement effect of nanometre-sized metallic (Pd, Ag and Cu) or metallic oxide (FexOy) nanoparticles on fermentative hydrogen production from glucose by a Clostridium butyricum strain. These nanoparticles (NP) of about 2–3 nm were encapsulated in porous silica (SiO2) and were added at very low concentration (10−6 mol L−1) in batch hydrogen production test. The cultures containing iron oxide NP produced 38% more hydrogen with a higher maximum H2 production rate (HPR) of 58% than those without NP or with silica particles only. The iron oxide NP were used in a 2.5 L sequencing-batch reactor and showed no significant effect on the yields (established at 2.2 molhydrogen molglucose−1) but an improvement of the HPR (+113%, reaching a maximum HPR of 86 mLhydrogen L−1 h−1). These results suggest an improvement of the electron transfers trough some combinations between enzymatic activity and inorganic materials.