Calcinated MIL-100(Fe) as a CO2 adsorbent to promote biomass productivity of Arthrospira platensis cells

Abstract In order to solve the problems of short residence time and low diffusion of CO2 gas in microalgal solution, calcinated metal-organic framework MIL-100(Fe) were first used as CO2 adsorbents to promote the growth of Arthrospira platensis cells by increasing carbon fixation. The adsorbent (MIL-100(Fe)-4 h) containing unsaturated metal sites, improved the conversion of CO2 to dissolved inorganic carbon by 52.3% and concentration of HCO3– by 20.0% in culture medium, as compared to the medium without CO2 adsorbent added. The increased HCO3– concentration facilitated carboxysome accumulation (increased to 21.7 times) to activate the photosynthetic Calvin cycle in Arthrospira cells. The increased cell growth rate promoted cell volume by 132% and knot length by 102%, while the fractal dimension of the cell surface decreased by 13.5%. The biomass productivity of Arthrospira cells cultivated with the CO2 adsorbent MIL-100(Fe)-4 h remarkably increased by 81.9%.