Ethanol, adsorption

J. J. Kipling. Proc. 2nd Intern. Congress of Surface Activity Part II 202-8CV (1957). Adsorption ethanol on SiOi, AI2O3, and carbon. 

L. Robert. Compi. rend. 234, 2066-7 (1952). Adsorption ethanol, aniline, acetic acid on SiOa. 

Vapor Adsorption. Ethanol and heptane vapor adsorption isotherms on cellulose are illustrated in Figure 6 for temperatures of 24.3 C and 26.5°C. The isotherms indicate multi-layer adsorption, which is typical for vapor adsorption on polymeric materials (16). Adsorption is sensitive to the temperature of both vapors and is decreased significantly by increasing the temperature from 24.3°C to 26.5 C. 

We have considered the surface tension behavior of several types of systems, and now it is desirable to discuss in slightly more detail the very important case of aqueous mixtures. If the surface tensions of the separate pure liquids differ appreciably, as in the case of alcohol-water mixtures, then the addition of small amounts of the second component generally results in a marked decrease in surface tension from that of the pure water. The case of ethanol and water is shown in Fig. III-9c. As seen in Section III-5, this effect may be accounted for in terms of selective adsorption of the alcohol at the interface. Dilute aqueous solutions of organic substances can be treated with a semiempirical equation attributed to von Szyszkowski [89,90]... 

The location and shape of the entire electrocapillary curve are affected if the general nature of the medium is changed. Fawcett and co-workers (see Ref. 126) have used nonaqueous media such as methanol, V-methylformamide, and propylene carbonate. In earlier studies, electrocapillaiy curves were obtained for O.OIA/ hydrochloric acid in mixed water-ethanol media of various compositions [117, 118]. The surface adsorption of methanol, obtained from... 

Fig. XI-11. Relation of adsorption from binary liquid mixtures to the separate vapor pressure adsorption isotherms, system ethanol-benzene-charcoal (n) separate mixed-vapor isotherms (b) calculated and observed adsorption from liquid mixtures. (From Ref. 143.)...

Wanless E J and Christenson H K 1994 Interaction between surfaces in ethanol adsorption, capillary condensation, and solvation forces J. Chem. Rhys. 101 4260-7... 

The strength of dispersion interaction of a solid with a gas molecule is determined not only by the chemical composition of the surface of the solid, but also by the surface density of the force centres. If therefore this surface density can be sufficiently reduced by the pre-adsorption of a suitable substance, the isotherm may be converted from Type II to Type III. An example is rutile, modified by the pre-adsorption of a monolayer of ethanol the isotherm of pentane, which is of Type II on the unmodified rutile (Fig. 5.3, curve A), changes to Type III on the treated sample (cf. Fig. 5.3 curve B). Similar results were found with hexane-l-ol as pre-adsorbate. Another example is the pre-adsorption of amyl alcohol on a quartz powder... 

Fig. 53 Adsorption of pentane vap>our at 273 K on a sample of nonporous rutile before and after modification of the surface by pre-adsorption of ethanol. Curve (A), unmodified surface curve (B), surface containing 52 pmol of ethanol. (After Parfitt.)...

Common examples of compounds that are amenable to carbon adsorption are aromatics (benzene, toluene) and chlorinated organics (trichloroethylene, trichloroethane [71-55-6, 75 -(9(9-j5y, tetrachloroethylene, polychlorinated biphenyls (PCBs), DDT /T(9-77-77, pentachlorophenol [87-86-5J. Compounds that are not adsorbed effectively by carbon include ethanol [64-17-5], diethylene glycol [111-46-6], and numerous amines (butylamine [109-73-9, 13952-84-6, 75-64-9], triethanolamine [102-71-6], cyclohexylamine [108-91-8], hexamethylenediamine [108-91-8] (1). Wastewater concentrations that are suitable for carbon adsorption are generally less than 5000 mg/L. 

SG sols were synthesized by hydrolysis of tetraethyloxysilane in the presence of polyelectrolyte and surfactant. Poly (vinylsulfonic acid) (PVSA) or poly (styrenesulfonic acid) (PSSA) were used as cation exchangers, Tween-20 or Triton X-100 were used as non- ionic surfactants. Obtained sol was dropped onto the surface of glass slide and dried over night. Template extraction from the composite film was performed in water- ethanol medium. The ion-exchange properties of the films were studied spectrophotometrically using adsorption of cationic dye Rhodamine 6G or Fe(Phen) and potentiometrically by sorption of protons. 

Adsorption of methanol and ethanol from gas phase on the surfaee of VO, was smdied by isotherms of resistanee (R, Om - t, s). 

SO as to end the air mixture to adsorber No. 2. The system is then fully automatic. Solvents which have been successfully recovered by the activated carbon adsorption method include methanol, ethanol, butanol, chlorinated hydrocarbons including perchlorethylene, which boils at 121 C (250 °F), ethyl ether, isopropyl ether, the acetates up to amyl acetate, benzene, toluene, xylene, mineral spirits, naphtha, gasoline, acetone, methyl ethyl ketone, hexane, carbon disulfide, and others. 

S g of ethyl glycinate hydrochloride were dissolved in 400 cc of ethanol and 33.5 g of salicylic aldehyde were added. It is refluxed for half an hour and cooled. 38 cc of triethylamlne and 25 g of Raney nickel are then added whereafter hydrogenation is carried out at room temperature and under atmospheric pressure. After hydrogen adsorption was complete, the mixture was filtered and the alcohol evaporated off. The residue was taken up with acidified water, extracted with ether to eliminate part of the by-products, consisting mainly of o-cresol, then made alkaline with ammonia and extracted with ethyl acetate. The solvent was removed in vacuo and the residue crystallized from ether/petroleum ether. 36.7 g of o-hydroxybenzyl-aminoacetlc acid ethyl ester melting at 47°C are obtained. 

Adsorption phenomena from solutions onto sohd surfaces have been one of the important subjects in colloid and surface chemistry. Sophisticated application of adsorption has been demonstrated recently in the formation of self-assembhng monolayers and multilayers on various substrates [4,7], However, only a limited number of researchers have been devoted to the study of adsorption in binary hquid systems. The adsorption isotherm and colloidal stabihty measmement have been the main tools for these studies. The molecular level of characterization is needed to elucidate the phenomenon. We have employed the combination of smface forces measmement and Fomier transform infrared spectroscopy in attenuated total reflection (FTIR-ATR) to study the preferential (selective) adsorption of alcohol (methanol, ethanol, and propanol) onto glass surfaces from their binary mixtures with cyclohexane. Om studies have demonstrated the cluster formation of alcohol adsorbed on the surfaces and the long-range attraction associated with such adsorption. We may call these clusters macroclusters, because the thickness of the adsorbed alcohol layer is about 15 mn, which is quite large compared to the size of the alcohol. The following describes the results for the ethanol-cycohexane mixtures [10],... 

FIG. 3 Plots of half the range of attraction (see Fig. 2) and the apparent thickness of the ethanol adsorption layer vs. the ethanol concentration. 

FIG. 6 Plausible structure of the adsorption layer composed of ethanol clnsters. 

The prepared MAC adsorbents were tested for benzene, toluene, 0-, m-, p-xylene, methanol, ethanol, iso-propanol, and MEK. The modified content of all MACs was 5wt% with respect to AC. The specific surface areas and amounts of VOC adsorbed of MACs prepared in this study are shown in Table 1. The amounts of VOC adsorbed on 5wt%-MAC with acids and alkali show a similar tendency. However, the amount of VOC adsorbed on 5wt%-PA/AC was relatively large in spite of the decrease of specific surface area excepting in case of o-xylene, m-xylene, and MEK. This suggests that the adsorption of relatively large molecules such as 0-xylene, m-xylene, and MEK was suppressed, while that of small molecules was enhanced. It can be therefore speculated that the phosphoric acid narrowed the micropores but changed the chemical nature of surface to adsorb the organic materials strongly. 

The reason for enhancement of adsorption performance of PA/AC was considered to be due to combination effect of increase of BET surface area and chemical modification by the treatment with PA. Consequently, lwt%-PA/AC was determined to be a best candidate as an adsorbent for removing benzene, toluene, p-xylene, methanol, ethanol, and iso-propanol. Therefore, lwt%-PA/AC was used as the adsorbent to investigate the adsorption isotherm, adsorption and desorption performance. 

The same resin was used for the purification via downstream processing of carminic acid, the natural colorant extracted from cochineal. By a direct adsorption method, a crude extract was applied on the polymeric bed gel and the adsorption kinetics studied using elution with hydrochloric acid and ethanol. The desorbed pure carminic acid concentrated under vacuum yielded a final product that complied with Codex Alimentarius requirements and FAO/OMS norms. 

Direct measurement of adsorptive stripping voltaimnetric peaks using HMDE 0.60 V and accumulation potential of -0.40V Dilution in phosphate buffer and water, analyzed in Vis region Ion pair formation with octadecyltrimethylammonium bromide at pH 5.6, extraction of ion pair into n-butanol Sample solution mixed with 1 M HCl, ethanol and purification on Sephadex DEAE 25 gel, gel beads are filtered off, packed into 1 nun cell and absorbance measured... 

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