A comparison between STR, TBR and five different HFR modules showed that the polydimethylsiloxane (PDMS-HFR) provided better gas liquid mass transfer (1063 h-1) followed by the TBR (421 h-1) and STR (114 h-1). In addition, the use of 0.3 wt% methyl-functionalized silica nanoparticles was reported to enhance the mass transfer of syngas components into the medium leading to a significant increase in the levels of biomass, ethanol and acetic acid production. Besides assessing the mass transfer capabilities of different reactor configurations, researchers have recently focused on developing new techniques to measure the dissolve concentrations of CO and H2 gases in the liquid phase to determine the CO and H2 mass transfer coefficients