Abstract
Some microalgae are particularly attractive as a renewable feedstock for biodiesel production due to their rapid growth, high content of triacylglycerols, and ability to be grown on non-arable land. Unfortunately, obtaining oil from algae is currently cost prohibitive in part due to the need to pump and process large volumes of dilute algal suspensions. In an effort to circumvent this problem, we have explored the use of anion exchange resins for simplifying the processing of algae to biofuel. Anion exchange resins can bind and accumulate the algal cells out of suspension to form a dewatered concentrate. Treatment of the resin-bound algae with sulfuric acid/methanol elutes the algae and regenerates the resin while converting algal lipids to biodiesel. Hydrophobic polymers can remove biodiesel from the sulfuric acid/methanol, allowing the transesterification reagent to be reused. We show that in situ transesterification of algal lipids can efficiently convert algal lipids to fatty acid methyl esters while allowing the resin and transesterification reagent to be recycled numerous times without loss of effectiveness.
Highlights
Some strains of algae show promise as a sustainable source of biofuel due to their rapid growth, ability to grow on non-arable land, and high triacylglycerol (TAG) content
Since algae were eluted off the resin by 5% sulfuric acid in methanol, a reagent that catalyzes the transesterification of esterified fatty acid to fatty acid methyl esters (FAMEs), tests were carried out to measure conversion of lipids in the eluate to FAME
The results show that FAME recovery from the resin (11.0% of dry cell weight (DCW)) was comparable to that obtained by direct hexane extraction [11.8% of DCW; Figure 3(c)]
Summary
Some strains of algae show promise as a sustainable source of biofuel due to their rapid growth, ability to grow on non-arable land, and high triacylglycerol (TAG) content. The extraction solvent must be removed and recovered prior to conversion of lipids to biodiesel and there are attending questions about pollution of the air and contamination of the biomass with solvents This is considered a large part of the cost in processing algae [5]. One study examined a two-step procedure where the acyl groups of component lipids were hydrolyzed with base and re-esterified in excess sulfuric acid/methanol [20] Appear to dissolve in the sulfuric acid reagent and esterified fatty acids are converted to FAMEs (biodiesel) This one step harvesting and transesterification process can potentially eliminate many of the costly steps of processing algae to biofuel
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