University of Qom Advances in Energy and Materials Research 3041-8836 2 6 2025 06 25 Integrated Stress-Induced Lipid Enhancement and Supercritical CO₂ Extraction for Efficient Biodiesel Production from Chlorella vulgaris 44 53 4575 10.22091/jaem.2026.14935.1036 EN Mohsen Dehnamaki Department of Biochemistry, College of Basic Sciences, Science and Research Branch, Islamic Azad University, Tehran, Iran 0009-0001-3764-0816 Abolghasem Esmaeili Fereidouni Department of Fisheries, Faculty of Animal Science and Fisheries, Sari Agricultural Sciences and Natural Resource University, Sari, Iran 0000-0002-4307-9420 Ramezan Ali Khavarinejad Department of Biochemistry, College of Basic Sciences, Science and Research Branch, Islamic Azad University, Tehran, Iran 0000-0001-8884-9049 Seyed Masoud Kazemi Tabaei Zavareh Department of Chemistry, Faculty of Science, Islamic Azad University, Qom Branch, Qom, Iran 0000-0003-4776-9784 Journal Article 2025 01 25 This study evaluates the efficiency of supercritical carbon dioxide (SC-CO₂) combined with n-hexane and ethanol as co-solvents for lipid extraction from Chlorella vulgaris cultivated under stress conditions for biodiesel production. The microalgae were grown using a two-stage cultivation strategy and divided into three groups: control (pre-stress), Treatment 1 (nutrient deprivation, pH 11, and 2 M NaCl for 24 h), and Treatment 2 (nutrient deprivation and 2 M NaCl for 72 h). Extraction was performed at pressures of 250, 300, and 350 bar and temperatures of 50 and 70 °C.<br />The total lipid contents for the control, Treatment 1, and Treatment 2 were 8.78 ± 0.45%, 57.4 ± 0.75%, and 55.3 ± 1.03%, respectively. The highest fatty acid yield (>99%) was achieved at 350 bar and 50 °C across all groups. The biodiesel properties of all samples met ASTM and EN standards. These findings indicate that the combination of stress-induced lipid accumulation and SC-CO₂ extraction represents an efficient strategy for biodiesel production from Chlorella vulgaris. https://jaem.qom.ac.ir/article_4575_4d82e12b81b256fe560614da1c68b4b7.pdf