Catalytic conversion of COsub.2 with the surplus glycerol (GL) produced from biodiesel manufacturing has attracted much academic and industrial attention, which proves the urgent requirement for ...developing high-performance catalysts to afford significant environmental benefits. Herein, titanosilicate ETS-10 zeolite-based catalysts with active metal species introduced by impregnation were employed for coupling COsub.2 with GL to efficiently synthesize glycerol carbonate (GC). The catalytic GL conversion at 170 °C miraculously reached 35.0% and a 12.7% yield of GC was obtained on Co/ETS-10 with CHsub.3CN as a dehydrating agent. For comparison, Zn/ETS- Cu/ETS-10, Ni/ETS-10, Zr/ETS-10, Ce/ETS-10, and Fe/ETS-10 were also prepared, which showed inferior coordination between GL conversion and GC selectivity. Comprehensive analysis revealed that the presence of moderate basic sites for COsub.2 adsorption-activation played a crucial role in regulating catalytic activity. Moreover, the appropriate interaction between cobalt species and ETS-10 zeolite was also of great significance for improving the glycerol activation capacity. A plausible mechanism was proposed for the synthesis of GC from GL and COsub.2 in the presence of CHsub.3CN solvent over Co/ETS-10 catalyst. Moreover, the recyclability of Co/ETS-10 was also measured and it proved to be recycled at least eight times with less than 3% decline in GL conversion and GC yield after a simple regeneration process through calcination at 450 °C for 5 h in air.
This paper deals with the results of quantum chemical modeling of the monoacyl-sn-glycerol 2D cluster formation at the air/water interface using a semi-empirical PM3 method. The impact of the 2 or 3 ...positions of the acyl substituent on the thermodynamics of the monolayer formation is assessed for surfactants with an acyl substituent CnHsub.2n+1COO chain length of n = 6–17 carbon atoms. The calculation shows a significant change in the spontaneous clusterization threshold for isomeric compounds, which differs only in the position of the acyl substituent with respect to the glycerol backbone. This change is almost equal to substituent shortening by approximately two methylene fragments. At the same time, the geometric parameters of the unit cell for resulting monolayers are not affected so drastically. The 2D films in question possess an oblique or orthorhombic unit cell with parameters for 2 and 3-monoacyl-sn-glycerol monolayers, as follows: a = 4.91 Å and 4.82 Å and b = 5.00 Å and 4.92 Å, with hydrocarbon chains tilted at t = 23.0° and 23.5°. The calculated results are in accordance with existing experimental data obtained using grazing incidence X-ray diffraction measurements and the π-A isotherm technique.
Triacylglycerol (TAG) is an important product in oil-producing organisms. Biosynthesis of TAG can be completed through either esterification of fatty acids to glycerol backbone, or through ...esterification of 2-monoacylglycerol. This review will focus on the former pathway in which two precursors, fatty acid and glycerol-3-phosphate (G3P), are required for TAG formation. Tremendous progress has been made about the enzymes or genes that regulate the biosynthetic pathway of TAG. However, much attention has been paid to the fatty acid provision and the esterification process, while the possible role of G3P is largely neglected. Glycerol is extensively studied on its usage as carbon source for value-added products, but the modification of glycerol metabolism, which is directly associated with G3P synthesis, is seldom recognized in lipid investigations. The relevance among glycerol metabolism, G3P synthesis and lipid production is described, and the role of G3P in glycerol metabolism and lipid production are discussed in detail with an emphasis on how G3P affects lipid production through the modulation of glycerol metabolism. Observations of lipid metabolic changes due to glycerol related disruption in mammals, plants, and microorganisms are introduced. Altering glycerol metabolism results in the changes of final lipid content. Possible regulatory mechanisms concerning the relationship between glycerol metabolism and lipid production are summarized.
Our understanding of the continental climate development in East Asia is mainly based on loess–paleosol sequences and summer monsoon precipitation reconstructions based on oxygen isotopes (δ18O) of ...stalagmites from several Chinese caves. Based on these records, it is thought that East Asian Summer Monsoon (EASM) precipitation generally follows Northern Hemisphere (NH) summer insolation. However, not much is known about the magnitude and timing of deglacial warming on the East Asian continent. In this study we reconstruct continental air temperatures for central China covering the last 34,000yr, based on the distribution of fossil branched tetraether membrane lipids of soil bacteria in a loess–paleosol sequence from the Mangshan loess plateau. The results indicate that air temperature varied in phase with NH summer insolation, and that the onset of deglacial warming at ~19kyr BP is parallel in timing with other continental records from e.g. Antarctica, southern Africa and South-America. The air temperature increased from ~15°C at the onset of the warming to a maximum of ~27°C in the early Holocene (~12kyr BP), in agreement with the temperature increase inferred from e.g. pollen and phytolith data, and permafrost limits in central China.
Comparison of the tetraether membrane lipid-derived temperature record with loess–paleosol proxy records and stalagmite δ18O records shows that the strengthening of EASM precipitation lagged that of deglacial warming by ca. 3kyr. Moreover, intense soil formation in the loess deposits, caused by substantial increases in summer monsoon precipitation, only started around 12kyr BP (ca. 7kyr lag). Our results thus show that the intensification of EASM precipitation unambiguously lagged deglacial warming and NH summer insolation, and may contribute to a better understanding of the mechanisms controlling ice age terminations.
► Air temperature reconstruction for East Asia based on branched GDGTs in Chinese loess. ► Deglacial atmospheric warming leads summer monsoon intensification by more than 3kyr. ► Onset of deglacial warming and monsoon precipitation were decoupled.
The aim of this study was to investigate the effect of pre-exercise glycerol and sodium-induced hyperhydration on fluid retention (mL), half-marathon (21.1 km) time-trial performance (min) and mean ...core temperature (°C) in trained runners in hot conditions. Descriptive statistics were reported as mean ± SD and results were reported as mean and 95% confidence intervals (lower bound, upper bound). ...the enhanced fluid retention did not provide a thermoregulatory advantage or half-marathon performance benefit in hot conditions.
Aims
To assess the ability of various newly isolated or belonging in official collections yeast strains to convert biodiesel‐derived glycerol (Gly) into added‐value compounds.
Methods and Results
Ten ...newly isolated yeast strains belonging to Debaryomyces sp., Naganishia uzbekistanensis, Rhodotorula sp. and Yarrowia lipolytica, isolated from fishes, metabolized Gly under nitrogen limitation. The aim of the study was to identify potential newly isolated microbial candidates that could produce single‐cell oil (SCO), endopolysaccharides and polyols when these micro‐organisms were grown on biodiesel‐derived Gly. As controls producing SCO and endopolysaccharides were the strains Rhodotorula glutinis NRRL YB‐252 and Cryptococcus curvatus NRRL Y‐1511. At initial Gly (Gly0) ≈40 g l−1, most strains presented remarkable dry cell weight (DCW) production, whereas Y. lipolytica and Debaryomyces sp. produced non‐negligible quantities of mannitol and arabitol (Ara). Five strains were further cultivated at increasing Gly0 concentrations. Rhodotorula glutinis NRRL YB‐252 produced 7·2 g l−1 of lipid (lipid in DCW value ≈38% w/w), whereas Debaryomyces sp. FMCC Y69 in batch‐bioreactor experiment with Gly0 ≈80 g l−1, produced 30–33 g l−1 of DCW and ~30 g l−1 of Ara. At shake‐flasks with Gly0 ≈125 g l−1, Ara of ~48 g l−1 (conversion yield of polyol on Gly consumed ≈0·62 g g−1) was achieved. Cellular lipids of all yeasts contained in variable concentrations oleic, palmitic, stearic and linoleic acids.
Conclusions
Newly isolated, food‐derived and non‐previously studied yeast isolates converted biodiesel‐derived Gly into several added‐value metabolites.
Significance and Impact of the Study
Alternative ways of crude Gly valorization through yeast fermentations were provided and added‐value compounds were synthesized.
Fibrous TiO.sub.2 layer was formed on a metal Ti plate by soaking it in a KOH solution and subsequently firing it in air at 600 °C for 2 h. Hydrophobic solid-liquid bulk composite (SLBC) was prepared ...by impregnation of a commercial silicone-based oil into the fibrous TiO.sub.2 layer after coating with fluoroalkylsilane. Based on the spreading coefficients from interface energies, the topmost solid surface of the SLBC was covered by the oil film when a water-glycerin mixture droplet was placed on the surface. The mixture droplets slid down the SLBC with acceleration. Particle image velocimetry (PIV) analysis revealed rolling and slipping modes in the sliding of the mixture droplets on the SLBC surface. During sliding, the coefficient of the viscous drag force was correlated with the velocity ratio (U.sub.total/U.sub.slip). Results suggest that the estimation of the internal fluidity of the liquid droplet was feasible to some degree by evaluating the coefficient during droplet sliding with constant acceleration on the SLBC surface.
•Global crude glycerol market will provide approximately 680,000 tonnes of highly impure crude glycerol by 2024.•A large focus is set on the use of sustainable (biogenic) adsorbents such as ...sludge-derived material, tea waste, bentonite, and others.•Advanced crude glycerol purification technologies are now encompassing not just pressure-driven technologies but also thermally- and electrochemically-driven membrane processes.•Problems remain with fouling with all three membrane processes due to the high MONG content which still needs to be treated by physio-chemical methods.
The increasing effort of the global community to reduce dependency on fossil fuels led to an increase in the production of biodiesel and therefore the oversupply of crude glycerol. Different steps are necessary to ensure this oversupply of highly impure, waste-based crude glycerol (approximately 680,000 tonnes by 2024) can be made suitable for applications. This review paper aims to give an overview of the recent developments of the global glycerol market and discusses advanced crude glycerol purification technologies (as compared to physio-chemical treatments). The market overview involves information on the relevance of the global glycerol market and the different grades of glycerol which are produced. Additionally, different application areas for glycerol are detailed; including current industrial solutions, challenges, and outlooks. The second part reports newly proposed crude glycerol purification technologies from industry and recent research since 2014, their advantages and disadvantages, and feasibility in terms of industrial implementation at scale. The results of this review suggest that pressure-, thermally- and electrochemically-driven membrane-based separation technologies could solve the issue of expensive large scale vacuum distillation columns lowering capital and operating expenditures reaching > 99 % of glycerol purity. However, the increase of lower quality glycerol generated resulting from 2nd generation bio-diesel plants presents challenges due to the increasing ash and matter organic non-glycerol (MONG) impurities (due to the use of waste-based feedstocks in biodiesel production). As result, hybrid solutions may be needed since advanced purification technologies cannot be used as stand-alone solutions but need to be accompanied by a proper pre-treatment.
•Lactobacillus diolivorans efficiently converts crude glycerol to 1,3-propanediol.•L. diolivorans is not inhibited by 0.7g/l furfural and 0.3g/l 5-HMF.•Conversion of biobased resources to up to 85g/l ...with a productivity of 0.45g/lh.
Lactobacillus diolivorans was evaluated as a potential organism for production of 1,3-propanediol under industrially relevant conditions. Crude glycerol of different origins has been tested and showed no inhibitory effects on growth or production. Using crude glycerol from biodiesel production from palm oil 85g/l 1,3-propanediol have been obtained with a productivity of 0.45g/lh in a fed-batch cultivation. Sugar necessary for the formation of biomass was replaced with a hydrolysate from lignocellulosic material resulting in 75g/l 1,3-propanediol and a productivity of 0.36g/lh. Lignocellulosic hydrolysate contained the potential inhibitors furfural and 5-hydroxymethylfurfural at concentrations of 0.7 and 0.3g/l, respectively. Addition of furfural and 5-hydroxymethylfurfural to batch cultures in said concentrations did not show inhibitory effects on growth or 1,3-propanediol production.
Different mechanisms of networking in hydrogels based on silicon tetraglycerolate
(STG), titanium tetraglycerolate (
TTG), and combined silicon tetraglycerolate–titanium tetraglycerolate (
STG/TTG) ...precursors.
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► The gelation of silicon– and titanium–glycerol precursors was investigated. ► The gelation time depends on pH or electrolyte addition in an opposite way. ► Silicon–glycerol hydrogel is a polymeric single-phase system. ► Titanium–glycerol hydrogels are colloid or polymeric systems.
Formation of organic/inorganic hydrogels based on silicon– and titanium–glycerol precursors synthesized by transesterification of alkoxy derivatives in excess of glycerol was investigated. The precursors in excess of glycerol and obtained gels were studied by chemical and physical methods including gelation kinetics, IR spectroscopy, XRD, dynamic and electrophoretic light scattering, mechanical deformation, which disclosed the basic difference in the gelation mechanism and structure of network in the hydrogels. Due to this difference, the gelation time of silicon– and titanium–glycerol precursors depended on pH or electrolyte addition in an opposite way. In the wide pH range, silicon–glycerol hydrogel was a polymeric single-phase system formed by the polymeric network homogeneously swollen in liquid water/glycerol medium. Flory–Rehner theory applied to the elastic modulus of these gels gave 40–180 monomer base units in the subchains of the network depending on water content in the gel. The mechanism of networking was three-dimensional polycondensation promoted by the electrically charged functional groups attached to the flexible polymeric chains. Electrolyte solutions provided the gelation according to Hofmeister series. Titanium–glycerol hydrogels were heterogeneous colloid systems at pH
>
1.5 and single-phase polymeric gels at lower pH. Electrolyte solutions provided the gelation according to Schultze–Hardy rule.
![Transformation of CO[sub.2]...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/1420-3049/small "Transformation of CO[sub.2] with Glycerol to Glycerol Carbonate over ETS-10 Zeolite-Based Catalyst")
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