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Regenerating Diethanolamine Aqueous Solution for CO2 Absorption Using Microalgae

Al-Zuhair, Sulaiman, AlKetbi, Sara, Al-Marzouqi, Mohamed
Industrial biotechnology 2016 v.12 no.2 pp. 105-108
Chlamydomonas, Chlorella, absorption, aqueous solutions, biomass, biotechnology, carbon, carbon dioxide, energy requirements, freshwater, lipids, microalgae, pigments, proteins
The high energy requirements associated with regenerating amine solution represents the main challenge for its use in carbon-dioxide (CO₂) removal processes. In this work, freshwater microalgae strains have been used to remove dissolved CO₂ from an aqueous solution of diethanolamine (DEA) and regenerate the solution with a far lower energy requirement. Using microalgae has the additional advantage of producing biomass that can be readily used to produce valuable products, such as lipids, proteins, and pigments. The ability of three strains—Chlamydomonas sp., Chlorella sp., and Pseudochlorococcum sp.—to grow in DEA solution saturated with CO₂ was tested. The effectiveness of the selected strains to utilize the dissolved CO₂ as a carbon source and reduce its concentration has also been assessed. It was found that the three tested strains grew well in 10% DEA solution saturated with CO₂, with specific growth rates of 0.365, 0.352, and 0.669/day, for Chlamydomonas sp., Chlorella sp., and Pseudochlorococcum sp., respectively. The strains were also capable of removing the dissolved CO₂ with drop rate of 0.0120, 0.135, and 0.0123 mole/mL/day. After regeneration, the amine solution regained 85% of its initial capacity. These results demonstrate a significant advantage over conventional regeneration processes of amine solutions used for CO₂ absorption.