Alcohols adsorption content

Wu SJ, Li FT, Wang HT, Fu L, Zhang BR, U GT (2010) Effects of poly (vinyl alcohol) (PVA) content on preparation of novel thiol-functionalized mesoporous PVA/Si02 composite nanofiber membranes and their application for adsorption of heavy metal ions from aqueous solution. Polymer 51 6203-6211... 

Additives. Because of their versatility, imparted via chemical modification, the appHcations of ethyleneimine encompass the entire additive sector. The addition of PEI to PVC plastisols increases the adhesion of the coatings by selective adsorption at the substrate surface (410). PEI derivatives are also used as adhesion promoters in paper coating (411). The adducts formed from fatty alcohol epoxides and PEI are used as dispersants and emulsifiers (412). They are able to control the viscosity of dispersions, and thus faciHtate transport in pipe systems (413). Eatty acid derivatives of PEI are even able to control the viscosity of pigment dispersions (414). The high nitrogen content of PEIs has a flame-retardant effect. This property is used, in combination with phosphoms compounds, for providing wood panels (415), ceUulose (416), or polymer blends (417,418) with a flame-retardant finish. 

The formation of silicon-flvxyride bonds on the surface of silica after treatment with hydrogen fluoride was never proven directly. However, there is a pronounced change in the adsorption and wetting properties. The silica becomes hydrophobic as was mentioned in a patent to Kimberlin (279a). Neimark and collaborators (279b) found a type V isotherm in the methanol adsorption on silica gel which had been treated with a solution of SiF in absolute alcohol. Wilska (280) obtained a water-repellent silica when solutions of HaSiPg were precipitated with ammonia. The Si—F bond is hydrolyzed only slowly. A considerable fluorine content of 7-10% F was reported in an older patent (281) for a silica that had been prepared by hydrolysis of SiF. ... 

The solution is introduced into the drum, which is then closed with a lid and set in motion for one or more hours. A side lid is then opened permitting alcohol to evaporate thereby gradually predrying the powder. During the latter operation a small amount of graphite is added so that its total content amounts to 0.25-0.3%. The evaporation of alcohol from the drum may be combined with the recovery of this solvent. For this purpose the lid is not removed but connected with a duct producing a reduced pressure within the drum. The solvent thus drawn off is then recovered either by condensation or adsorption. 

Additives to starch exert varying effects on the kinetics of water sorption. For example, lipids do not significantly affect the content of adsorbed water. The mode of starch defatting can also influence moisture sorption by molecules of the defatting solvent occupying active centers of sorption.389 The addition of either sucrose or lipids to starch has the same effect on both branches of the hysteresis curve.386,398 Some additives, such as dimethyl sulfoxide or ammonium rhodanide, induce selectivity of the adsorption and solvation of starch 411 Sulfur dioxide accelerates water sorption regardless of the temperature.412 Pretreatment of starch with sulfur dioxide usually increases the water sorption.413 Studies on the sorption of components of water-alcohol mixtures are discussed in Section IV. 

Nevertheless, addition of bentonite at the beginning of the alcoholic fermentation may deplete the assimilable nitrogen content of the must due to electrostatic binding and adsorption. This may result in fermentation sticking and/or hydrogen sulfide production. Addition of an exogenous source of nitrogen eliminates these potential problems. 

Correlation equations relating surfactant chemical structure to performance characteristics and physical properties have been established. One atmosphere foaming properties of alcohol ethoxyl-ates and alcohol ethoxylate derivatives have been related to surfactant hydrophobe carbon chain length, ethylene oxide content, aqueous phase salinity, and temperature. Similar correlations have been established for critical micelle concentration, surfactant cloud point, and surfactant adsorption. 

A good example of separation on the basis of affinity is the separation of alcohol/ water mixtures using a hydrophobic, silicalite membrane. Pervaporation of an ethanol/ water mixture through such a membrane resulted the removal of the alcohol from the mixture [16]. The separation selectivities achieved are between 10 and 60, depending on temperature and the alcohol content in the feed. In this way azeotropes can be broken. The reason for this is that the principle of separation, namely, differences in adsorptive behavior, is different from separation based on vapor pressure differences, used in distillation. Another example of such a separation is the pervaporation of an acetic acid/water mixture through a silicalite membrane, resulting in the removal of acetic acid [17]. 

The yields of A-fraction by the above method are substantially higher than the 22-23% previously reported by butyl alcohol fractionation, since the latter method does not give as complete a separation. From the iodine adsorption of raw corn starch and of the purified A-fraction, Bates, French and Rundle have calculated the content of A-fraction in corn starch as 22%. This low value is due to the use of incompletely defatted starch, and its agreement with the yield by butyl alcohol precipitation is purely coincidental. Under preferred methods of testing, exhaustively defatted corn starch adsorbs 5.3% iodine. Dividing this latter value by the 19.0% iodine adsorption for the recrystallized A-fraction, a theoretical content of 28% is calculated for corn starch, in agreement with the yields by Pentasol fractionation. 

Silica and alumina have the highest surface activity when the adsorbents are free of physisorbed water. Addition of water blocks the most active sites on the surface since water, as a polar adsorptive, is preferentially adsorbed. Other polar compounds such as alcohols can also adsorb irreversibly at the surface. Consecutive adsorption of water deactivates the adsorbent surface and the solute retention will decrease concurrently. For this reason the water content of the mobile phase solvents should be controlled carefully if an apolar mobile phase is used (Unger, 1999). The water content only influences retention when apolar eluents are used, e.g. hexane or heptane. When these solvents are mixed with 10% or more of a moderately polar solvent (e.g. acetone, ethyl acetate) the dependency disappears. The influence can be decreased by the addition of a small amount of acetonitrile to the mobile phase. 

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