Fecitrate converted from Fe2O3 particles in coal-fired flue gas promoted microalgal biomass and lipid productivities

In order to reutilize Fe2O3 particles in flue gas from coal-fired power plant as a ferrum nutrient for improving microalgae growth, Na-Citrate was proposed to chelate FeCl3 derived from Fe2O3 and HCl reactions to promote biomass and lipid productivities of Chlorella PY-ZU1. Fe-Citrate gave much higher biomass and lipid productivities than FeCl3, Fe-EDTA, Fe-DTPA and Fe-HEDTA, because organic chelator prevented Fe3+ from depositing, lower stability constant resulted in easier dissociation of ferric chelate, smaller chelate facilitated Fe2+ (reduced from Fe3+) transportation through cell membranes. The biomass growth and photosynthetic capacity of Chlorella PY-ZU1 cultivated with Fe-Citrate (converted from Fe2O3 particles) medium were similar to those with commercial ferric ammonium citrate medium. The biomass and lipid productivities of Chlorella PY-ZU1 cultivated with 5 mg L−1 Fe-Citrate medium were 1.30 and 1.72 times, respectively, higher than those with FeCl3 growth medium. [Display omitted] •Na-Citrate was proposed to chelate FeCl3 derived from Fe2O3 and HCl reactions.•Fe-Citrate gave much higher microalgal biomass and lipid productivities than FeCl3, Fe-EDTA, Fe-DTPA and Fe-HEDTA.•A transmembrane absorption mechanism was proposed for Fe-Citrate and other Fe-chlates.•The maximum biomass and lipid productivities were obtained in 5 mg L−1 Fe-Citrate medium.