ABSTRACT
In this paper, we publish information that has not been published before, but is needed to evaluate processes for wet lipid extraction from microalgae and recover the solvent N-ethylbutylamine (EBA), for example as presented in [1], the article entitled "Process evaluation of swing strategies to recover N-ethylbutylamine after wet lipid extraction from microalgae" in which we evaluate and interpret temperature swing and CO2-swing approaches. This includes selection of microalgae slurry concentration used in the extraction process, information on switching of EBA with CO2, data on the amount of EBA in solid residue after extraction, recoverability from the solid residue, and on recoverability of the solvent from the aqueous raffinate by liquid-liquid extraction and distillation of the solvent and EBA after the liquid-liquid extraction. Also information on phase behavior of binary mixtures of EBA and water is presented. Finally, detailed information on all flows in the process flow diagrams that are given in the article [1] is presented.
ABSTRACT
Algae are an interesting feedstock for producing biofuel via hydrothermal liquefaction (HTL), due to their high water content. In this study, algae slurries (5-7 wt% daf) from different species were liquefied at 250 and 375 °C in batch autoclaves during 5 min. The aim was to analyze the influence of strain-specific parameters (cell structure, biochemical composition and growth environment) on the HTL process. Results show big variations in the biocrude oil yield within species at 250 °C (from 17.6 to 44.8 wt%). At 375 °C, these differences become less significant (from 45.6 to 58.1 wt%). An appropriate characterization of feedstock appeared to be critical to interpret the results. If a high conversion of microalgae-to-biocrude is pursued, near critical conditions are required, with Scenedesmus almeriensis (freshwater) and Nannochloropsis gaditana (marine) leading to the biocrude oils with lower nitrogen content from each growth environment.
Subject(s)
Biofuels , Microalgae , Photobioreactors , Temperature , Biomass , Chromatography, Gel , Culture Media , Nitrogen/chemistry , Scenedesmus/metabolism , Species Specificity , Stramenopiles/metabolism , Time FactorsABSTRACT
The strong anthropogenic increase in the emission of CO(2) and the related environmental impact force the developments towards sustainability and carbon capture and storage (CCS). In the present work, we combine the high product yields and selectivities of CO(2) absorption processes with the advantages of membrane technology in a membrane contactor for the separation of CO(2) from CH(4) using amino acid salt solutions as competitive absorption liquid to alkanol amine solutions. Amino acids, such as sarcosine, have the same functionality as alkanol amines (e.g., monoethanolamine=MEA), but in contrast, they exhibit a better oxidative stability and resistance to degradation. In addition, they can be made nonvolatile by adding a salt functionality, which significantly reduces the liquid loss due to evaporation at elevated temperatures in the desorber. Membrane contactor experiments using CO(2)/CH(4) feed mixtures to evaluate the overall process performance, including a full absorption/desorption cycle show that even without a temperature difference between absorber and desorber, a CO(2)/CH(4) selectivity of over 70 can be easily achieved with the sarcosine salt solution as absorption liquid. This selectivity reaches values of 120 at a temperature difference between absorber and desorber of 35 degrees C, compared to a value of only 60 for MEA under the same conditions. Although CO(2) permeance values are somewhat lower than the values obtained for MEA, the results clearly show the potential of amino acid salt solutions as competitive absorption liquids for the energy efficient removal of CO(2). In addition, due to the low absorption of CH(4) in sarcosine compared to MEA, the loss of CH(4) is reduced and significantly higher CH(4) product yields can be obtained.
