Impact of silica oxide and functionalized silica oxide nanoparticles on growth of Chlorella vulgaris and its physicochemical properties

Abstract

In this study, silica oxide nanoparticles (SiO2 NPs) and methyl-functionalized SiO2 NPs were compared for their effects on the growth of Chlorella vulgaris, production of biomass, and lipid content. The synthesised nanoparticles were characterised by using techniques such as FTIR, XRD, UV-Vis, FESEM with EDX and TEM. The synthesised nanoparticles were used to enhance the gas-liquid interface areas, which increase the concentration of dissolved carbon dioxide in the growth medium in order to increase the accumulation of lipid content in C. vulgaris cultures. The most effective way to improve the gas-liquid interface area was to use SiO2 NPs at a concentration of 0.3 wt%. The hydrophobic functional group methyl was added to the hydrophilic surfaces of SiO2 NPs. Methyl-functionalized SiO2 NPs improved the gas-liquid interface area more effectively than unmodified silica nanoparticles. The concentration of dissolved CO2 was 316.66 mg L−1 with methyl-functionalized SiO2 NPs. During microalgae culture, methyl-functionalized SiO2 NPs at a concentration of 0.3 wt% considerably improved the production of dry biomass, lipid, protein, carbohydrate, and chlorophyll contents as compared to the control.