Influence of the CO _2 absorbent monoethanolamine on growth and carbon fixation by the green alga Scenedesmus sp.

摘要

The influence of monoethanolamine (MEA) as a CO _2 absorbent on photoautotrophic culture of CO _2-fixing microalgae was investigated. When 300ppm MEA (4.92mM) was added to blank culture medium, the dissolved inorganic carbon and the molar absorption ratio increased to 51.0mg/L and 0.34molCO2/molMEA, respectively, which was an almost 6-fold increase in CO _2 solubility. When free MEA up to 300mg/L was added to a green alga Scenedesmus sp. culture that was supplied 5% (v/v) CO _2 at 0.1vvm, both cell growth rate and final cell density were enhanced compared to when no MEA was added. The cell growth rate reached 288.6mg/L/d, which was equivalent to 539.6mg-CO _2/L/d as a CO _2-fixation rate and enhancement of about 63.0% compared to not adding MEA. Chlorophyll-a content and nitrate consumption rate increased correspondingly. MEA doses higher than 400mg/L inhibited cell growth, probably due to toxicity of the carbamate intermediate.