Post-combustion carbon dioxide capture using amine solutions is an integral technology for reducing carbon dioxide emissions from the energy sector. However, environmental impacts and economic costs are restricting the implementation of amine absorbents. This study investigated the development of a sustainable algal based chemical absorption process to capture post-combustion carbon dioxide efficiently. Microalgal biomass was hydrolyzed to amino acids under basic conditions at 134oC. The supernatant of the hydrolysate was purged with carbon dioxide following centrifugation, and then underwent a desorption process to regenerate a chemical absorption algae-based solvent. A mass balance of the process showed that 31% of the mass into the process was recovered as an algal amino acid product. Another 30% exited the process as wet potassium carbonate which could be recovered as potassium hydroxide. The algal amino acid absorbent product contained 0.592 mol amino acid/L composed primarily of alanine, glutamic acid, glycine, aspartic acid, leucine, lysine, and proline. A trickling filter absorption column was built to determine the absorption capacity of the algal amino acid solution. The algal absorbent (0.731 ± 0.037 mol CO2/mol amine) had a higher absorption capacity than a synthetic amino acid absorbent (0.512 ± 0.014mol CO2/mol amine) composed of glycine, alanine, proline, and lysine. Both solutions were highly regenerable showing no signs (p<0.05) of deterioration after multiple absorption and desorption cycles based on the pH of the solution, absorption capacity, and ATR-FTIR spectra. Using algal biomass as a cheap and sustainable source of amino acids is a viable alternative to synthetic amino acid absorbents.
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