Abstract
Currently, lipid extraction remains a major bottleneck in microalgae technology for biofuel production. In this study, an effective and easily controlled cell wall disruption method based on electro-Fenton reaction was used to enhance lipid extraction from the wet biomass of Nannochloropsis oceanica IMET1. The results showed that 1.27 mM of hydroxide radical (HO•) was generated under the optimal conditions with 9.1 mM FeSO4 in a 16.4 mA·cm−2 current density for 37.0 min. After the electro-Fenton treatment, the neutral lipid extraction yield of microalgae (~155 mg) increased from 40% to 87.5%, equal to from 12.2% to 26.7% dry cell weight (DCW). In particular, the fatty acid composition remained stable. The cell wall disruption and lipid extraction processes were displayed by the transmission electron microscope (TEM) and fluorescence microscopy (FM) observations, respectively. Meanwhile, the removal efficiency of algal cells reached 85.2% within 2 h after the reaction was terminated. Furthermore, the biomass of the microalgae cultured in the electrolysis wastewater treated with fresh nutrients reached 3 g/L, which is 12-fold higher than that of the initial after 24 days. These finds provided an economic and efficient method for lipid extraction from wet microalgae, which could be easily controlled by current magnitude regulation.
Highlights
Microalgae is considered as a sustainable biomass source for producing biofuel, contributing to meet energy demands as well as addressing environmental concerns [1]
We examined the effects of different parameters (e.g., FeSO4 concentration, current density and time) on disruption of microalgae cell wall with response surface methodology (RSM)
This study study investigated investigated aa novel extraction based on the electro-Fenton reaction
Summary
Microalgae is considered as a sustainable biomass source for producing biofuel, contributing to meet energy demands as well as addressing environmental concerns [1]. Microalgae can bio-fix CO2 (4–14%, v/v) [2] into biomass, such as lipids, starch, proteins and pigments, abate greenhouse gas (GHG) emissions [3]. Several economic and technical constraints limit the industrial applications of microalgae-based biofuel, including high costs of production and low lipid extraction yield [4,5]. As the most useful sources for biodiesel production, triacylglycerols are the major components of microalgae lipid, which make up 20–50% of the total lipid [6,7,8,9,10,11], and disperse in the cytoplasm, bounded by a rigid cell wall. Effective extraction techniques are required to extract lipid from microalgae cells
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