Methods for production of fatty acid alkanolamides (FAAAs) from microalgae biomass
Provided herein are methods for fatty acid alkanolamide (FAAA) synthesis and isolation from lipid-containing algal biomass, and the products of such methods.
1. A method of fatty acid alkanolamide (FAAA) synthesis and isolation from lipid-containing algal biomass, the method comprising:
reacting the lipid-containing algal biomass with an alkanolamine, an alcohol, or a mixture of alkanolamine and alcohol, with or without catalysts, in a reaction solvent to achieve in situ conversion of fatty acyl donors (FADs) in the lipids to FAAA, fatty acid alkyl esters (FAAE), or a mixture of FAAA and FAAE;
recovering the FAAA, FAAE, or mixture of FAAA and FAAE from the reaction medium; and
converting any recovered FAAE to FAAA by reacting the recovered FAAE with alkanolamine in a second step.
2. The method of claim 1 , wherein the reaction solvent is an alcohol, and the in situ conversion of the FAD in the lipids results in formation of FAAE, the method comprising:
recovering FAAE as a separate phase; and
converting the recovered FAAE to FAAA in the second step by reacting the recovered FAAE with alkanolamine.
3. The method of claim 2 , wherein the reaction solvent is methanol, and the in situ conversion of the FAD in the lipids results in formation of FAAE comprising fatty acid methyl esters (FAMEs), the method comprising:
recovering the FAME as a separate phase; and
converting the recovered FAME to FAAA in the second step by reacting the recovered FAME with alkanolamine.
4. The method of claim 3 , wherein the FAMEs are produced through in situ transesterification by reacting the lipid-containing algal biomass directly with a mixture of methanol and an acid catalyst.
5. The method of claim 4 , wherein a recyclable solid-acid catalyst is used in the transesterification step.
6. The method of claim 5 , wherein the recyclable solid-acid catalyst comprises Amberlyst 15.
7. The method of claim 3 , wherein a two-step transesterification-followed-by-amidation with alkanalamides, with or without an amidation-catalyst, is used to recover algal lipids as FAAA products.
8. The method of claim 7 , wherein the amidation catalyst is sodium methoxide (NaOMe).
9. The method of claim 7 , wherein ethanolamine is used to convert the recovered FAME to fatty acid ethanolamide (FAEA) in the second step.
10. The method of claim 7 , wherein diethanolamine is used to convert the recovered FAME to fatty acid diethanolamide (FADEA) in the second step.
11. The method of claim 7 , wherein isopropanolamine is used to convert the recovered FAME to fatty acid diisopropanolamide (FADIPA) in the second step.
12. The method of claim 3 , wherein the steps are conducted a temperature of less than 120° C.
13. The method of claim 3 , wherein at least above 95% of the total lipids in the biomass is recovered as FAAA.
14. The method of claim 3 , wherein the recovered FAME is treated with 10 w/w % charcoal and filtered.
15. The method of claim 1 , wherein the lipid-containing algal biomass comprises the microalgae strain Schizochitrium limacinum or Chlorella Vulgaris.
16. The method of claim 1 , wherein the lipid-containing algal biomass comprises a heterotrophic unicellular alga.
17. The method of claim 1 , wherein the lipid-containing algal biomass comprises an alga which produces high levels of polyunsaturated fatty acids with a rapid growth rate.
18. The method of claim 3 , wherein freeze-dried microalgae biomass and Amberlyst 15 are mixed with methanol, and heated at 90° C.
19. The method of claim 18 , wherein the Amberlyst 15 is present at about 40% g/g-biomass, and the methanol is present at about 5 mL/g-biomass.
20. The method of claim 1 , wherein the reaction solvent is an alkanolamine and the lipids undergo in situ conversion directly to FAAA, the method further comprising recovering the FAAA from the reaction mixture through selective extraction into an immiscible organic solvent, and isolating the recovered FAAA from the organic solvent through distillation of the solvent.
21. The method of claim 20 , where the reaction solvent is ethanolamine and the in situ amidation reaction is conducted at a temperature of 120° C. or less, with or without a catalyst.
22. The method of claim 20 , where the reaction solvent is diethanolamine and the in situ amidation reaction is conducted at a temperature of 120° C. or less, with or without a catalyst.
23. The method of claim 20 , wherein the reaction solvent is diisopropanolamine and the in situ amidation reaction is conducted at a temperature of 120° C. or less, with or without a catalyst.
24. The method of claim 20 , wherein the immiscible organic solvent is EtOAc.
25. The method of claim 24 , wherein above 90% of the total lipids in the biomass are recovered as FAAA.
26. The method of claim 25 , wherein the recovered FAAA is treated with 10 w/w % charcoal and filtered to improve the color of the final product.