scholarly journals Use of Co-Solvents in Hydrothermal Liquefaction (HTL) of Microalgae

Energies ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 124
Author(s):  
Yang Han ◽  
Kent Hoekman ◽  
Umakanta Jena ◽  
Probir Das
Keyword(s):  
Ethylene Glycol ◽  
Chemical Processes ◽  
Hydrothermal Liquefaction ◽  
Solvent Mixtures ◽  
Reduced Viscosity ◽  
Viscosity Increase ◽  
Alcohol Water ◽  
Two Temperatures ◽  
Commercial Applications ◽  
Constant Yield

This study reviewed and summarized the literature regarding the use of alcohols during hydrothermal liquefaction (HTL) of algal biomass feedstocks. The use of both pure alcohols and alcohol-water co-solvents were considered. Based upon this review, laboratory experiments were conducted to investigate the impacts of different alcohol co-solvents (ethanol, isopropanol, ethylene glycol, and glycerol) on the HTL treatment of a specific saltwater microalga (Tetraselmis sp.) at two temperatures: 300 °C and 350 °C. Based on their performance, two co-solvents, isopropanol and ethylene glycol, were selected to explore the effects of varying solvent concentrations and reaction temperatures on product yields and biocrude properties. The type and amount of added alcohol did not significantly affect the biocrude yield or composition. Biocrude yields were in the range of 30–35%, while a nearly constant yield of 21% insoluble products was observed, largely resulting from ash constituents within the algal feedstock. The benefits of using alcohol co-solvents (especially isopropanol) were the reduced viscosity of the biocrude products and reduced rates of viscosity increase with biocrude aging. These effects were attributed mainly to the physical properties of the co-solvent mixtures (solubility, polarity, density, etc.) rather than chemical processes. Under the reaction conditions used, there was no evidence that the co-solvents participated in biocrude production by means of hydrogen donation or other chemical processes. Recovery and recycling of the co-solvent present various challenges, depending upon the type and amount of the co-solvent that is used. For example, glycol solvents are recovered nearly completely within the aqueous product stream, whereas simple alcohols are partitioned between the biocrude and aqueous product streams. In commercial applications, the slight benefits provided by the use of co-solvents must be balanced by the challenges of co-solvent recovery and recycling.

Thermodynamic properties of micellization of sodium dodecyl sulfate in binary mixtures of ethylene glycol with water

1996 ◽  
Vol 74 (9) ◽  
pp. 1616-1625 ◽  
Author(s):  
Kim Gracie ◽  
Dale Turner ◽  
R. Palepu
Keyword(s):  
Sodium Dodecyl Sulfate ◽  
Ethylene Glycol ◽  
Ultrasonic Velocity ◽  
Sodium Dodecyl ◽  
Binary Solvent ◽  
Solvent Mixtures ◽  
Aqueous Mixtures ◽  
Degree Of Dissociation ◽  
Aggregation Numbers ◽  
Dodecyl Sulfate

Micellar properties of sodium dodecyl sulfate (SDS) in aqueous mixtures of ethylene glycol (EG) were determined using techniques such as conductivity, density, EMF, surface tension, viscosity, ultrasonic velocity, and spectroscopy (fluorescence). The effective degree of disssociation of micelles (α) was determined using three different methods. Thermodynamics of micellization were obtained from the temperature dependence of critical micelle concentrations (cmc) values. The difference in Gibbs energies of micellization [Formula: see text] of SDS, between water and mixed solvent systems, was calculated to evaluate the influence of cosolvent on the micellization process. Surfactant aggregation numbers (Ns) obtained from static fluorescence quenching methods indicated a decrease in the aggregation numbers with increasing concentration of ethylene glycol in the binary solvent mixtures. In addition, the micropolarity of the micellar interior was determined from the pyreneI1/I3 ratios. These values were consistent with a decrease in the micropolarity surrounding the probe molecule as the EG content in the solvent mixture was increased. Key words: thermodynamics, micellization, aggregation numbers, ultrasonic velocity, degree of dissociation.

scholarly journals DMSO-Free Programmed Cryopreservation of Fully Dissociated and Adherent Human Induced Pluripotent Stem Cells

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Igor I. Katkov ◽  
Natalia G. Kan ◽  
Flavio Cimadamore ◽  
Brandon Nelson ◽  
Evan Y. Snyder ◽  
...  
Keyword(s):  
Stem Cells ◽  
Ethylene Glycol ◽  
Pluripotent Stem Cells ◽  
Toxicity Tests ◽  
Adherent Cells ◽  
Freezing And Thawing ◽  
Rock Inhibitor ◽  
Commercial Applications ◽  
Induced Pluripotent ◽  
Human Ipsc

Three modes for cryopreservation (CP) of human iPSC cells have been compared:STD: standard CP of small clumps with 10% of CPA in cryovials,ACC: dissociation of the cells with Accutase and freezing in cryovials, andPLT: programmed freezing of adherent cells in plastic multiwell dishes in a programmable freezer using one- and multistep cooling protocols. Four CPAs were tesetd: dimethyl sulfoxide (DMSO), ethylene glycol (EG), propylene glycol (PG), and glycerol (GLY). The cells inACCandPLTwere frozen and recovered after thawing in the presence of a ROCK inhibitor Y-27632 (RI). EG was less toxic w/o CP cryopreservation than DMSO and allowed much better maintenance of pluripotency after CP than PG or GLY. The cells were cryopreserved very efficiently as adherent cultures (+RI) in plates (5-6-fold higher than STD) using EG and a 6-step freezing protocol. Recovery under these conditions is comparable or even higher than ACC+RI.Conclusions. Maintenance of cell-substratum adherence is a favorable environment that mitigates freezing and thawing stresses (ComfortFreeze®concept developed by CELLTRONIX). CP of cells directly in plates inready-to-goafter thawing format for HT/HC screening can be beneficial in many SC-related scientific and commercial applications such as drug discovery and toxicity tests.

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