Kinetic and thermodynamic studies of eicosapentaenoic acid extraction from Nannochloropsis oceanica using tetramethyl ammonium chloride and microwave irradiation

Abstract

Microalgae have garnered widespread attention as a sustainable source of pharmaceuticals and nutraceuticals. As for extracting lipids from microalgae, the combination of microwave-assisted extraction (MAE) and ionic liquids (IL) is shown to be promising. However, such an undertaking usually requires a large consumption of expensive ILs. This study innovatively employs tetramethyl ammonium chloride ([TMAm][Cl]) as an additive in water medium to associate with microwave-assisted ionic liquid extraction (MAILE) in extracting lipids from Nannochloropsis oceanica (N. oceanica) microalgae. In extraction, knowledge of reaction kinetics is crucial since it provides the foundation for developing, controlling, and improving the processes of extraction. Herein, using MAILE, lipids are extracted from N. oceanica microalgae and transesterified to eicosapentaenoic acid (EPA). Mass transfer kinetics are, therefore, investigated using the first and second-order rate law and Patricelli’s model. In the development of models, the influence of temperature (60–90°C) and reaction time (1–25 min) on EPA extraction is empirically evaluated. From the thermodynamic study, the positive values of ΔS (+0.10 kJ mol-1K-1) and ΔH (+32.50 kJ mol-1) and the negative value of ΔG (-1.68 to -4.75 kJ mol-1) confirm that this process is endothermic in nature, irreversible and spontaneous. MAILE proves to be a promising approach for the extraction of high-quality EPAs. Due to its low cost, rapid operation, and environmental friendliness, it is seen to be suitable for both pharmaceutical and nutraceutical applications.

Bioactive fatty acids from non‐conventional lipid sources and their potential application in functional food development

“…Most microalgae have thick cell walls that are diffcult to penetrate during extraction (Amaro et al, 2018 ), requiring cell disruption, such as exposure to pulsed electric fields, microwave irradiation, and ultrasound (Motlagh et al, 2022 ) to improve lipid extraction efficiency. Ultrasound‐assisted extraction (UAE) has been used as a green extraction approach due to its ability to improve lipid recovery and kinetics at reduced temperature, solvent, and extraction time compared to conventional methods (Marsol‐Vall et al, 2022 ).…”

“…Most microalgae have thick cell walls that are diffcult to penetrate during extraction (Amaro et al, 2018), requiring cell disruption, such as exposure to pulsed electric fields, microwave irradiation, and ultrasound (Motlagh et al, 2022) to improve lipid extraction efficiency.…”

“…Ultrasound-assisted extraction (UAE) has been used as a green extraction approach due to its ability to improve lipid recovery and Microwave-assisted extraction (MAE) has also been demonstrated to be an effective and straightforward method for extracting lipids from microalgae. Motlagh et al (2022) reported that, the combination of MAE and ionic liquids alongside tetramethyl ammonium chloride ([TMAm][Cl]) proved to be an effective method for extracting lipids from N. oceanica. This approach also led to the transesterification of FAs to EPA.…”

Repurposing disposed surgical face masks into activated carbon for efficient sorption of bio recalcitrant malathion pesticide

“…Concurrently, the positive ∆𝑆° suggests an increase in disorder or randomness within the system. This combination of energetic favorability (negative ∆𝐺°) and entropic favorability (positive ∆𝑆°) reflects a thermodynamically advantageous scenario where the reaction proceeds spontaneously, releasing energy and increasing disorder in the system [42,47,48].…”