Optimisation of ultrasonication pretreatment on microalgae Chlorella Vulgaris & Nannochloropsis Oculata for lipid extraction in biodiesel production
Amarnath Krishnamoorthy, Cristina Rodríguez, Andy Durrant
Abstract
A wide variety of nutritious products and biofuels can be produced from microalgae . Their applications span across various sectors such as food, medical, and energy industries. Microalgal cell disruption is a crucial aspect in the production processes as it facilitates the extraction of bio-products stored within them. One of the commonly extracted compounds from microalgae is lipids, which constitute a high percentage of their composition. In this study, we conducted ultrasonic pre-treatment on two different microalgae species, namely Chlorella vulgaris and Nannochloropsis oculata . The pre-treatment involved ultrasonic frequencies of 37 and 80 kHz, exposure times of 10, 15, and 20 min, and extraction times of 2, 3, and 4 h. By utilising ultrasonic frequencies, we induced acoustic cavitation to break the microalgae cell walls and extract lipids. The experimental design followed a Response Surface Methodology (RSM) to evaluate the effect of ultrasonication pretreatment parameters on lipid extraction . In comparison to previously published studies, our findings indicate that higher frequencies of ultrasonication lead to increased lipid extraction from microalgae. The highest lipid yield achieved in our study was 11.54% for Chlorella vulgaris and 17.91% for Nannochloropsis oculata , using the input factors of 80 kHz frequency, 20 min of running time, and 4 h of extraction time. Our results contribute to the existing body of knowledge by demonstrating the efficacy of ultrasonic pre-treatment in lipid extraction from microalgae. By providing a quantitative comparison with previous studies, this study highlight the novel aspects of work and its potential implications for the production of biofuels and other valuable products from microalgae.