Assessing the effect of engineered nanoparticles on microalgae Tetradesmus obliquus, for enhanced biomass production and CO2 sequestration

This study engineered a series of novel nickel-doped ceria nanoparticles to assess their supplementation effects on the microalgae Tetradesmus . Nanoparticles (NPs) were synthesized using the co-precipitation method and characterized by various techniques. The synthesized NPs were utilized to assess the effects of different dosages on the physiology ( F v /F m ), chlorophyll-a content, and biochemical composition of T. obliquus growth. Different dosages (5, 10, 20, and 50 mg/L) of 0 %Ni@CeO 2 , 0.25 %Ni@CeO 2 and 0.5 %Ni@CeO 2 NPs were added in BG11 for investigation. Results show that 0.25 %Ni@CeO 2 (20 mg/L) NPs show the highest (2.19 g/L) biomass production compared to BG11 (1.67 g/L), and other NPs added media. Similarly, the protein content in 0.25 %Ni@CeO 2 (20 mg/L) medium was ~14 % and 29.74 % higher compared to BG11 and 0 %Ni@CeO 2 (5 mg/L) medium. The lipid and carbohydrate content in NPs-supplemented growth media shows a higher yield than BG11. The maximum higher (22.06 MJ/kg) heating value (HHV) was observed in 0.25 %Ni@CeO 2 (20 mg/L), followed by 20.67 MJ/kg in 0 %Ni@CeO 2 (20 mg/L). Similarly, the highest CO 2 fixation rate (0.28 gCO 2 /L/d) was observed in 0.25 %Ni@CeO 2 (20 mg/L). This research shows that 0.25 %Ni@CeO 2 (20 mg/L) addition in BG11 medium is a promising strategy to enhance microalgae growth, biochemical content, and CO 2 sequestration. Furthermore, this study provides a detailed insight into the interaction mechanism between 0.25 %Ni@CeO₂ NPs and the microalgal photosystem. The finding might be easily scaled up at the demonstration scale for enhanced biomass production. • Engineered Ni-doped ceria NPs enhance T. obliquus growth and CO₂ sequestration. • 0.25 %Ni@CeO₂ (20 mg/L) achieved the highest biomass and chlorophyll-a yield. • Protein, lipid, and carbohydrate content increased with Ni-doped ceria NPs. • Maximum heating value (22.06 MJ/kg) observed with 0.25 %Ni@CeO₂ (20 mg/L). • The study reveals the interaction between Ni@CeO₂ NPs and the microalgal photosystem.