Gas-to-liquid mass transfer of hydrogen (H₂) was investigated in a gas–liquid reactor with a continuous gas phase, a batch liquid phase, and liquid mixing regimes relevant to assessing kinetics of microbial H₂ consumption. H₂ transfer was quantified in real-time with a H₂ microsensor for no mixing, moderate mixing [100 rotations per minute (rpm)], and rapid mixing (200 rpm). The experimental results were simulated by mathematical models to find best-fit values of volumetric mass transfer coefficients—k_La—for H₂, which were 1.6/day for no mixing, 7/day for 100 rpm, and 30/day for 200 rpm. Microbiological H₂-consumption experiments were conducted with Methanobacterium bryantii M.o.H. to assess effects of H₂ mass transfer on microbiological H₂-threshold studies. The results illustrate that slow mixing reduced the gas-to-liquid H₂ transfer rate, which fell behind the rate of microbiological H₂ consumption in the liquid phase. As a result, the liquid-phase H₂ concentration remained much lower than the liquid-phase H₂ concentration that would be in equilibrium with the gas-phase H₂ concentration. Direct measurements of the liquid-phase H₂ concentration by an in situ probe demonstrated the problems associated with slow H₂ transfer in past H₂ threshold studies. The findings indicate that some of the previously reported H₂-thresholds most likely were over-estimates due to slow gas-to-liquid H₂ transfer. Essential requirements to conduct microbiological H₂ threshold experiments are to have vigorous mixing, large gas-to-liquid volume, large interfacial area, and low initial biomass concentration.

中文翻译：

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氢（H2）传质在微生物H2阈值研究中的作用。

在气液反应器中研究了氢气（H ₂）的气液传质，该反应器具有连续的气相，间歇式液相和与评估微生物H ₂消耗动力学相关的液体混合方式。使用H ₂微型传感器实时定量H ₂转移，以确保不混合，适度混合[100转/分钟（rpm）]和快速混合（200 rpm）。通过数学模型对实验结果进行仿真，以求出H ₂的体积传质系数的最佳拟合值k _L a ，无混合时为1.6 /天，100 rpm为7 /天，200为30 /天。转速 进行了微生物H ₂消耗实验Bryantii MoH细菌用于评估H ₂传质对微生物H ₂阈值研究的影响。结果表明，缓慢混合降低了气液H _2的转移速率，这落后于液相中微生物H _2的消耗速率。结果，液相H ₂浓度仍然远低于与气相H ₂浓度平衡的液相H ₂浓度。用原位探针直接测量液相中H _2的浓度表明了过去H中H ₂转移缓慢的问题_2个阈值研究。研究结果表明，由于气对液H _2的缓慢转移，某些先前报道的H ₂阈值很可能被高估了。进行微生物H ₂阈值实验的基本要求是剧烈混合，较大的气液体积，较大的界面面积以及较低的初始生物质浓度。