High-efficiency carbon dioxide capture using an algal amino acid salt solution

This study developed a novel, high-efficiency, and bio-based CO2 absorbent - microalgal amino acid salt solution (MAASS). The MAASS was prepared by hydrolyzing microalgal biomass with potassium hydroxide. Alanine, glutamic acid, glycine, aspartic acid, leucine, lysine, and proline are the primary amino acids in the MAASS with a total amino acid concentration of 0.592 mol/L. The absorption and desorption results on a synthetic flue gas with 10 %(v/v) CO2 and 90 %(v/v) air showed that the MAASS had an absorption capacity of 1.27 mol CO2/mol amine, which is 3.4 and 3.1 times higher than monoethanolamine (MEA) and the reported pure amino acid salt solution, respectively. The MAASS was regenerable, showing no signs of deterioration in the absorption capacity after eight consecutive absorption and desorption cycles. The mass and energy balance analysis concluded that combining algal cultivation and MAASS absorption would lead to a technically feasible and environmentally friendly CO2 capture technology.