Influence of mesoporous iron based nanoparticles on Chlorella sorokiniana metabolism during photosynthetic biogas upgrading

Abstract

Three different mesoporous iron based nanoparticles (NPs) were added to Chlorella sorokiniana batch cultures devoted to photosynthetic biogas upgrading to enhance CO2 biofixation: Fe2O3, carbon coated zero valent iron NPs containing 7.26 % (wt%) of iron (CALPECH NPs) and carbon coated zero valent iron NPs containing 31.38 % (wt%) of iron (SMALLOPS NPS). The three types of NPs enhanced CO2 adsorption and therefore biogas upgrading in tests conducted in 1.2 L enclosed photobioreactors. However, the addition of 70 mg L−1 of CALPECH NPs resulted in a 2-fold enhancement in the microalgae productivity, and a carbohydrate and lipid content increase by 56 % and 25 %, respectively compared to the control assay. Under UV and visible light irradiation the addition of Fe2O3 NPs resulted in a 5.3-times fold enhancement in carbohydrate content when 70 mg L−1 was added. Similarly, the addition of 20 mg L−1 of SMALLOPS NPs increased the lipid content by 11 % under UV irradiation. Interestingly, CALPECH NPs did not significantly influence C. sorokiniana composition, suggesting that these particular NPs can act as UV scavengers. Therefore, the addition of mesoporous nanoparticles could improve CO2 fixation and microalgae productivity during photosynthetic biogas upgrading.