Supersaturation of dissolved H2 and CO2 during fermentative hydrogen production with N2 sparging

TLDR: The common assumption that sparging increases the H2 yield because of lower dissolved H2 concentrations may be incorrect, because H2 was not lowered into the range necessary to affect the relevant enzymes, according to an improved manual headspace-gas chromatographic method.

Abstract: Dissolved H2 and CO2 were measured by an improved manual headspace-gas chromatographic method during fermentative H2 production with N2 sparging. Sparging increased the yield from 1.3 to 1.8 mol H2/mol glucose converted, although H2 and CO2 were still supersaturated regardless of sparging. The common assumption that sparging increases the H2 yield because of lower dissolved H2 concentrations may be incorrect, because H2 was not lowered into the range necessary to affect the relevant enzymes. More likely, N2 sparging decreased the rate of H2 consumption via lower substrate concentrations.