ABSTRACT
Enhancement of oxygen mass transfer has been observed in the presence of colloidal dispersions of magnetite (Fe3O4) nanoparticles coated with oleic acid and a polymerizable surfactant. These fluids improve gas-liquid oxygen mass transfer up to 6 fold in an agitated, sparged, cell-free reactor and show remarkable stability in high-ionic strength media over a wide pH range. A combination of experiments using physical and chemical methods has been used to show that the mass transfer coefficient kL and the volumetric mass transfer coefficient kLa are enhanced in the presence of nanoparticles. An increase of 40% in the oxygen uptake rate has been achieved in Escherichia Coli fermentation at a 5.5-L scale by using 0.6% w/w particles dispersed in fermentation media. The enhancement in mass transfer is directly translatable into increased fermenter productivity.
