Abstract
The production of fatty acids ethyl esters (FAEEs) to be used as biodiesel from oleaginous microalgae shows great opportunities as an attractive source for the production of renewable fuels without competing with human food. To ensure the economic viability and environmental sustainability of the microbial biomass as a raw material, the integration of its production and transformation into the biorefinery concept is required. In the present work, lipids from wet Isochrysis galbana microalga were extracted with ethyl acetate with and without drying the microalgal biomass (dry and wet extraction method, respectively). Then, FAEEs were produced by lipase-catalyzed transesterification and esterification of the extracted lipids with ethanol using lipase B from Candida antarctica (CALB) and Pseudomonas cepacia (PC) lipase supported on SBA-15 mesoporous silica functionalized with amino groups. The conversion to FAEEs with CALB (97 and 85.5 mol% for dry and wet extraction, respectively) and PC (91 and 87 mol%) biocatalysts reached higher values than those obtained with commercial Novozym 435 (75 and 69.5 mol%). Due to the heterogeneous nature of the composition of microalgae lipids, mixtures with different CALB:PC biocatalyst ratio were used to improve conversion of wet-extracted lipids. The results showed that a 25:75 combi-lipase produced a significantly higher conversion to FAEEs (97.2 mol%) than those produced by each biocatalyst independently from wet-extracted lipids and similar ones than those obtained by each lipase from the dry extraction method. Therefore, that optimized combi-lipase biocatalyst, along with achieving the highest conversion to FAEEs, would allow improving viability of a biorefinery since biodiesel production could be performed without the energy-intensive step of biomass drying.
Highlights
Nowadays, we are facing a major energy crisis caused by the decline of fossil reserves and by the problems caused by their use
When the microalgal oil, used as feedstock, was extracted by the wet method, the results showed a reduction in fatty acids ethyl esters (FAEEs) production from 97 to 85.5 mol% and from 91 to 87 mol% using CalB and Pseudomonas cepacia (PC) lipase-based biocatalysts, respectively
For the wet extraction route, both CalB and PC lipase-based biocatalysts showed similar activity (85.5 and 87 mol%, respectively) so that SBA-15-NH2 G-CalB seems to be more sensitive to the presence of water or other polar compounds likely extracted during the wet process
Summary
We are facing a major energy crisis caused by the decline of fossil reserves and by the problems caused by their use. Due to its high content of free fatty acids in the lipids extracted from microalgae, the most common way to carry out the biodiesel process is by using acid catalysts. Biodiesel (FAEEs) were produced using enzyme catalysis from lipids extracted with ethyl acetate from both wet and dry biomass from microalgae For this purpose, two enzymes from different origins were assessed, namely lipase B from the fungus Candida antarctica (CalB) and lipase from the bacterium Pseudomonas cepacia (PC) which were supported on amino-functionalized. The results were compared to those obtained with the commercial Novozym 435® catalyst Both enzymes were combined in different proportions to evaluate the synergistic activity and selectivity towards biodiesel production
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
