Effect of colloidal silver nanoparticles on biodiesel quality of Nannochloropsis oculata

In this study, the effect of different concentrations (1-50 mg/L) of colloidal Ag-NPs investigated on the growth, fatty acids profile and biodiesel indices of N. oculata, after estimating EC50 (20.88 mg/L).

In this research, N. oculata was selected owing to fast growth and its ability to synthesize lipids for biodiesel production. This microalga exposed to colloidal silver nanoparticles under marine conditions for 72 h. The optical density (OD) and fatty acid profiles were investigated using spectrophotometric analysis and gas chromatography, respectively. Statistical analysis growth data was performed using ANOVA and Duncan's multiple test at 2% probability level.

The algal growth significantly decreased in N. oculata cells treated with the 5-50 mg/L of Ag-NPs.  The increase of saturated fatty acids (SFAs) and polyunsaturated fatty acids (PUFAs) as well as the decrease of monounsaturated fatty acids (MUFAs) contents were also observed in response to 25 mg/L of Ag-NPs in compared to the control. The important indicators of biodiesel oxidative stability containing LCSF, CFPP and CP increased in N. oculata exposed to Ag-NPs, while the level of DU decreased. The results of this study showed that despite the toxicity of silver nanoparticles, this nanoparticle can increase the biodiesel stability produced from N. oculata.