Adsorption Of Glycerol Research Articles

Aqueous-phase adsorption of glycerol and propylene glycol onto activated carbon

Adsorption of reactant and product species can have a major effect on local pore concentrations in activated carbon-supported metal catalysts. Individual and combined adsorption of glycerol (GO) and propylene glycol (PG) onto activated carbon in aqueous solution is reported here at concentration ranges of 0.05–2.0M and temperatures from 25°C to 160°C. Langmuir and Freundlich isotherms are used to model the single component data, with the Langmuir model best describing results below 0.75M. The extended Langmuir model has been used to model the competitive adsorption system – model parameters determined from single component experiments accurately predict two component adsorption data over the temperature and concentration ranges studied. Propylene glycol adsorbs more strongly than GO onto the activated carbon supports studied, and also adsorbs to a somewhat greater extent compared to GO. This is attributed to the greater organic character of PG, which favors its selective adsorption onto the support material.

Absorption of glycerol and its effects on the physical properties of a collagen material: Leather

AbstractAn aqueous solution of glycerol was applied to a polymeric biomaterial, leather, to evaluate its effects on the physical properties of leather, particularly stiffness. The initial strain energy, Young's modulus, and acoustic‐emission methods were used to characterize the stiffness of the resultant leather treated with these glycerol solutions. The measurements revealed that the glycerol treatment significantly reduced the stiffness of the dried leather, indicating the strong lubrication function of glycerol for leather. Experiments were also conducted to investigate the mechanism of glycerol adsorption into the leather matrix. Fick's second law of diffusion was employed to systematically derive a mathematical model for the absorption rate. The effect of temperature on the absorption rate was also included in the model by incorporation of the Arrhenius equation into Fick's second law of diffusion. The resultant model fits the experimental data very well. It not only depicts the mechanism of absorption but also predicts the absorption rate as a function of key variables. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1221–1231, 2003

Reaction of glycerol with fatty acids in the presence of ion-exchange resins: Preparation of monoglycerides

The preparation of monoglycerides from glycerol and fatty acids in the presence of ion-exchange resins is studied. A preliminary swelling in the glycerol inhibits the reaction, whereas a swelling of the resin in the oleic acid, before the reaction, increases the activity and the selectivity. This result shows that the competitive adsorption of glycerol and fatty acid influences greatly the esterification rate. Generally, water is an inhibitor of the esterification reaction (catalyst poisoning and thermodynamic equilibrium) and different procedures have already been suggested for its elimination. By using a molecular sieve as a water trap, the oleic acid conversion increases up to 90% without any change of the monoglyceride selectivity (85%). Moreover, owing to the pore structure of the catalyst, it has to be expected that the hydrocarbon chain length of the fatty acid will influence the activity and the selectivity, evidence of which we give in the present study. Finally, if an excess of glycerol increases the selectivity of the monoglycerides, it decreases the activity and can be considered as a selective inhibitor.

Adsorption of Glycols, Sugars, and Related Multiple −OH Compounds onto Activated Carbons. 1. Adsorption Mechanisms

Several different experimental methods were used to understand better the mechanisms of adsorption of glycerol, glycols, and sugars from dilute aqueous solution onto activated carbons. From batch equilibrium experiments, the affinity and capacity (25 °C) of carbons for single and multiple −OH compounds were greatest for solutes having larger positive deviations from solution ideality. Carbons with progressively oxidized surfaces exhibited reduced uptakes for all multiple −OH solutes. Larger isosteric heats of adsorption on carbons were measured for compounds with fewer −OH groups or higher molecular weight. Thermogravimetric analysis showed that the volatility of the adsorbed multiple −OH solute was reduced by higher molecular weight and solute hydrophobicity. Collectively, these findings show that the adsorption mechanism is characterized by: (a) attractive dispersion interactions between surface and solute, (b) solution-phase nonidealities, and (c) secondary, competitive interactions of the solute −OH groups(s) or surface oxygen groups with water.

Enzymatic synthesis of tricaprylin in a solvent-free system: lipase regiospecificity as controlled by glycerol adsorption on silica gel

Enzymatic synthesis of tricaprylin from caprylic acid (octanoic acid) and glycerol was carried out under solvent-free conditions. Kinetics of mono-, di- and tricaprylin synthesis and caprylic acid esterification in standard conditions (free glycerol) were slightly different from those obtained in the case of silica gel adsorbed glycerol. The critical role of the silica gel which behaves as a "reservoir" is proposed and it was shown that the use of silica gel facilitates reactions and improves the conversion yields at high glycerol concentrations.

Using Interfacial Tension Measurements To Study the Kinetics of Ferritin and Sugar Adsorption onto Mercury

The kinetics ofholoferritin, apoferritin, glucose, and glycerol adsorption onto a pendant mercury drop in aqueous solutions were investigated by measuring the mercury-water interfacial tension as a function of time. The apparatus used for interfacial tension measurement was constructed in-house and utilized the pendant drop method. To calculate the interfacial tension, the drop profile was digitized and then the experimental points were fitted according to the exact solution of the equation of capillarity by using the least-square optimization principle. In sugar solutions, the mercury-water interfacial tension relaxation and, hence, the adsorption onto the mercury surface were much faster than that in ferritin solutions. The decrease of the drop interfacial tension in the sugar solutions was similar to that in the sugar and ferritin mixed solutions. On the basis of these results, we concluded that sugars adsorb faster than ferritin, and that ferritin molecules attach weakly to the adsorbed sugar layer. Thus, sugars might act as spacers in the sugar and ferritin mixed solutions, protecting ferritin molecules from direct contact with the mercury surface.

Near-quantitative production of fatty acid alkyl esters by lipase-catalyzed alcoholysis of fats and oils with adsorption of glycerol by silica gel

A simple solution to the problem of incomplete reaction in lipase-catalyzed alcoholysis of triacylglycerol oils has been found. When immobilized Mucor meihei lipase was used to catalyze the reaction of tallow with three molar equivalents of butanol, the yield of butyl esters did not exceed 70% (w/w). If silica gel was added to the reaction mixture, it adsorbed the glycerol produced during the reaction and the yield increased to up to 98%. The optimum amount of silica gel was 1.25 weight equivalents to the glycerol produced. Other adsorbents were tested, e.g., cellulose, starch, charcoal, and celite, but none was as effective as silica gel. A variety of fats and oils could be used and all gave yields over 90%. Aliphatic alcohols varying in polarity between methanol and dodecanol also gave yields over 90%, although the highest yields were obtained from the most hydrophobic alcohols. The reaction could be carried out by circulating the reaction mixture through columns of enzyme and silica gel. Dehydration of the reaction mixture, and hence of the enzyme, by the silica gel caused loss of activity during repeated reuse of the enzyme. This problem could be minimized by increasing the water content of the initial reaction mixture.

Adsorption of glycerol on platinum in alkaline medium: effect of the electrode structure

The electro-oxidation of glycerol on platinum in alkaline medium shows structural effects, Pt(111) appearing to be the most active orientation. This results from different adsorption interactions of the glycerol molecule with the single-crystal plane. The number of electrons per platinum site, N eps, associated with the oxidation of the adsorbed glycerolic residues was thus determined. For each single-crystal plane considered, N eps has a value of around 2 at long adsorption times. At short adsorption times differences are observed according to the orientation, with values of N eps which can be greater than 2. The case of polycrystalline platinum is different, with a constant value of N eps of around 1.5 for the whole range of adsorption times studied. The value of N eps ≈ 2 determined for long adsorption times is in agreement with the first conclusions drawn from electromodulated IR reflectance spectroscopy experiments, which confirm the presence of linearly adsorbed CO. Other values of N eps can be explained either as a consequence of the breaking of CC bonds for N eps > 2 or by the formation of aldehyde functions for N eps < 2.

Enzymatic esterification of glycerol I. Lipase‐catalyzed synthesis of regioisomerically pure 1,3‐sn‐diacylglycerols

Regioisomerically pure 1,3‐sn‐diacylglycerols are conveniently prepared in high yields (&gt;80%) and in large quantities by enzymatic esterification of glycerol in the presence of various 1,3‐selective lipases(Chromobacterium viscosum, Rhizopus delemar, Rhizomucor miehei) and a variety of different acyl donors like free fatty acids, fatty acid alkyl esters and vinyl esters. All reactions are carried out in aprotic organic solvents of low water content, namelyn‐hexane, diethyl ether or tBuOMe. The creation of an artificial interphase between the solvent‐immiscible hydrophilic glycerol and the hydrophobic reaction media by the adsorption of glycerol onto a solid support prior to use was essential for the success of these transformations. The effects of reaction conditions and the regioselectivities of the lipases on the product yields are described in detail.

The electro-oxidation of glycerol on the gold(100)-oriented single-crystal surface and poly crystalline surface in 0.1 M NaOH

In this work, the oxidation of glycerol on a gold single-crystal surface with the (100) orientation has been studied with the aim of investigating the interfacial properties of the electrode surface in the absence and presence of glycerol. The change in the interfacial properties gives useful information about the nature of OH adsorption on a Au(100) electrode and about the process of adsorption and faradaic oxidation of glycerol in 0.1 M NaOH. The electrosorption of glycerol was also investigated at a polycrystalline gold electrode, by programmed potential voltammetry, in order to confirm the results obtained by double-layer capacity measurements

Radiotracer and Electrochemical Study of the Adsorption and Electrocatalytic Oxidation of Glycerol at a Platinized Platinum Electrode.

Radiotracer and Electrochemical Study of the Adsorption and Electrocatalytic Oxidation of Glycerol at a Platinized Platinum Electrode.

Adsorption of Glycerol on the Platinized Platinum Electrode

Adsorption of Glycerol on the Platinized Platinum Electrode

Characterization of clays by organic compounds

AbstractMany problems—from soil research to ceramics—require a reliable characterization of the clay minerals involved. This can be done using four clay-organic reactions: (i) staining tests and dye adsorption; (ii) glycerol and glycol adsorption; (iii) intercalation; (iv) alkylammonium ion exchange. Dye adsorption (staining tests) and glycerol adsorption allow a preliminary identification of the clay mineral groups. Intercalation reactions indicate minute differences between kaolins which cannot be detected by XRD and DTA. Alkylammonium ion exchange provides the best method for characterizing smectites and is sensitive to changes in the layer charge.

Glycerol Vapor Adsorption on Clay Minerals and Montmorillonitic Soil Clays

AbstractAdsorption isotherms of glycerol were obtained for clay fractions of montmorillonite, vermiculite, kaolinite, and eight soil clays at 80C in an evacuated system. The weight of glycerol required for monolayer formation was determined by application of the BET equation to adsorption data. Montmorillonite samples gave BET monolayer values from 211 to 230 mg glycerol/g of montmorillonite which is in the theoretical range. Monolayer values calculated for soil montmorillonites from BET monolayer values and corrected for impurities were 209 to 239 mg glycerol/g of montmorillonite in &lt; 0.08µ soil clays. The surface area values estimated from these soil montmorillonite monolayer values range from 738 m2/g to 844 m2/g. Vermiculite gave BET monolayer values of 40 mg and 96 mg/g of clay for 2 to 0.2µ and 0.2 to 0.08µ samples, respectively. This method appears to effectively measure the sorption surface of montmorillonite and indicates lower sorption surface of vermiculite than is suggested by its structural similarity to montmorillonite. Glycerol monolayer values indicate only modest reduction of particle size in &lt; 0.08µ compared to 0.2 to 0.08µ montmorillonite from soil clays and Wyoming bentonite. The success of glycerol adsorption on clays, in spite of a very low vapor pressure, suggests that more volatile polar organic molecules might effectively be studied by adsorption on clay surfaces.

A Comparison of Mg2+, Ca2+, and Sr2+ as Exchange Ions for Mineralogical Studies of Clays

AbstractStrontium‐, Ca2+‐, and Mg2+‐saturated clay minerals were studied with respect to X‐ray diffraction, differential thermal analysis, cation exchange capacity, and glycerol adsorption. In general, 3‐layer clay minerals saturated with Sr2+ lost interlayer water at lower temperatures and at higher vapor pressures than did Mg2+‐clays; Ca2+‐clays were intermediate. A clay mineral‐ion‐saturation interaction was apparent. Calcium‐ and Sr2+‐saturation of clays yielded similar values for cation exchange capacity. Strontium‐saturated 3‐layer clays retained more glycerol than did clays saturated with Ca2+. Expansion of vermiculite with glycerol and ethylene glycol was dependent on cation saturation and lattice charge. Strontium‐saturated vermiculites expanded to near 16Å. more readily than did Mg2+‐clays, and Ca2+‐clays were intermediate. Vermiculites with high lattice charge expanded less readily than did vermiculites with relatively low lattice charge.Strontium can satisfactorily substitute for Ca2+ and Mg2+ in routine mineralogical studies of clays though special care may be needed to control relative humidity. Additional information regarding lattice charge of 3‐layer clays may be obtained by using several divalent ion saturations.

Glycerol and Water Effects on X-Ray Sensitivity in Staphylococcus aureus

The variation of x-ray sensitivity of Staphylococcus aureus was studied over a range of glycerol concentrations to 95%. The relationship follows closely that described by the Langmuir adsorption equation. Extrapolation of the relationship to infinite glycerol concentration gives values of less than one- twentieth of the sensitivity of the cells in phosphate buffer. The results are not consistent with glycerol acting primarily either to prevent the oxygen- enhancement effect or by protection through the simple removal of water from the cells. Simple dehydration of the organism does not decrease x-ray sensitivity, provided a protective agent is not added before drying. It is proposed that protection by glycerol occurs through the adsorption of glycerol on sites usually occupied by water at the surface of important macromolecules within the cell.

Exchange Behavior of Kaolins of Varying Degrees of Crystallinity

Particle‐size fractions of several Georgia kaolins, which were prepared by sedimentation procedures, were examined from the standpoint of crystallinity, cation‐exchange capacity, and surface area. Crystallinity was studied using X‐ray techniques, exchange capacities were measured using the manganese saturation method, and surface areas were determined using glycerol adsorption techniques. A linear relation was obtained between surface areas and exchange capacities when areas were increased by decreasing the particle size or by changing from well‐crystallized to poorly crystallized kaolins. In most cases, the empirically determined crystallinity ratios indicated a change in crystallinity with change in particle size, the crystallinity generally increasing with decreasing particle size in individual samples. Unlike, however, the relation noted for exchange, the crystallinity did not consistently correlate with area changes both among the various samples and within the various particle‐size fractions of a single sample. These results suggest that the relatively high cation‐exchange capacity of poorly ordered kaolins is more directly a result of high surface area with crystallinity playing, at most, a very minor role.

Surface‐Area Determination of Kaolinite Using Glycerol Adsorption

Journal of the American Ceramic SocietyVolume 43, Issue 12 p. 671-672 Surface-Area Determination of Kaolinite Using Glycerol Adsorption K. H. WOODSIDE, K. H. WOODSIDESearch for more papers by this authorW. C. ORMSBY, W. C. ORMSBYSearch for more papers by this author K. H. WOODSIDE, K. H. WOODSIDESearch for more papers by this authorW. C. ORMSBY, W. C. ORMSBYSearch for more papers by this author First published: December 1960 https://doi.org/10.1111/j.1151-2916.1960.tb13638.xCitations: 7 The writers are, respectively, graduate assistant, Department of Chemistry, University of Rochester, Rochester, N. Y., and ceramic engineer, Engineering Ceramics Section, National Bureau of Standards, Washington, D. C. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article.Citing Literature Volume43, Issue12December 1960Pages 671-672 RelatedInformation

Softener absorption by regenerated cellulose. Uptake from 10% aqueous glycerol

AbstractThe softener content of regenerated cellulose film (gel film) in equilibrium with aqueous glycerol solution was found to be determined primarily by only two factors: the softener concentration of the solution and the volume of free space within the gel film. Volume changes of film in contact with 10% glycerol solutions are negligible. Preferential uptake of glycerol as the solution passes into the film is, at most, slight, amounting to no more than 0.04% at the concentration used. No evidence was found for a large enrichment within the gel film, as has been postulated, or for adsorption of glycerol on cellulose chains. The system, cellulose‐glycerol‐water, appears to be a polymer‐liquid mixture brought to equilibrium principally by diffusion. It appears that at 10% concentration, glycerol and probably other organic compounds are taken in by gel film by a diffusion process in which the free water in the film is replaced by solution without appreciable enrichment or change in volume. Water contained in the interchain spaces of cellulose is simply exchanged for softener solution. The free volume of the film as determined by the cellulose structure and the degree of crystallinity remains essentially unchanged on softener uptake at the softener concentration studied.