Sorption alcohol

N) [W3V18042(H20)12(X04)]-24H20 alcohols, secondary alcohols Sorption of water [184, 185]... 

Further comparison with benzene sorption on this sample yields striking results if the two isotherms are plotted on the same axis, as shown in Figure 1. The fact that these two isotherms may be completely superimposed suggests that the mechanism of tert-butyl alcohol sorption is similar to that observed in benzene sorption. This indicates that the sorption mechanism of tert-butyl alcohol on this material is more influenced by organic interactions with the surface phenyl groups than by polar interaction with surface hydroxyls. (It should be noted, however, that a small amount of rehydroxylation is indicated by the low pressure hysteresis.)... 

A summary of the features of n- and ferf-butyl alcohol sorption on the phenyl modified silica sample is presented in Table 1, together with information on nitrogen, water and benzene sorption for comparison.3... 

In Table XXV, the rates and amounts of absorption of various molecules are summarized (235). Polar molecules such as alcohol, ether, and amine are readily absorbed. In contrast, nonpolar molecules like hydrocarbons are sorbed only on the surface. The initial rates of absorption of molecules are plotted against the molecular size in Fig. 37. The initial rates of alcohol sorption greatly decrease as the molecular size increases from 20 A2 (methanol) to 35 A2 (1-butanol). The rates are higher for amines than for alcohols, regardless of the molecular size. This difference is due to the greater basicity of amines. Thus, it may be stated that the rate is primarily determined by the basicity (or polarity) and secondarily by the molecular size (235). 

In Fig. 6.15 are summarized the sorption isotherms of methanol, ethanol and propanol by Nafion [272,281 ], along with the data for water. It can be observed that for alcohol activity higher than 0.5 the alcohol sorption follows the order methanol > ethanol > propanol, as expected according to the size of the sorbate. At low alcohol activities the alcohol uptakes were nearly identical. The behavior of water uptake is different and could be due to the fact that in one case [272] the membrane was used without treatment, while Zhao et al. [281] performed the measurements on the expanded form. In the last case the sorption of water is higher than methanol, while for the untreated membrane more methanol is sorbed in the membrane as compared to water. The data by Jalani et al. [276] for a cast Nafion membrane, not shown in Fig. 6.15, indicates a similar behavior, with the uptake order at high activities being water tv methanol > ethanol > propanol. 

Theoretical and applied aspects of microwave heating, as well as the advantages of its application are discussed for the individual analytical processes and also for the sample preparation procedures. Special attention is paid to the various preconcentration techniques, in part, sorption and extraction. Improvement of microwave-assisted solution preconcentration is shown on the example of separation of noble metals from matrix components by complexing sorbents. Advantages of microwave-assisted extraction and principles of choice of appropriate solvent are considered for the extraction of organic contaminants from solutions and solid samples by alcohols and room-temperature ionic liquids (RTILs). 

Adsorption of lA of POMs with CV and Malachite Green (MG) on the polyurethane foams (PF) and some other adsorbents is investigated. While lA is fully adsorbed on the PF in wide pH range (0,4 M H SO - pH 4) extent of dye adsoi ption does not exceed 0,4%. lA are adsorbed faster then POMs. Extent of sorption of lA is 60-70% at 5 minutes and is complete after 15 minutes. lA can be eluted from PF most effectively by methylbutylketone, acetone or alcohols can be used too. 

The second type of interaction, displacement interaction, is depicted in Figure 10. This type of interaction occurs when a strongly polar solute, such as an alcohol, can interact directly with the strongly polar silanol group and displaces the adsorbed solvent layer. Depending on the strength of the interaction between the solute molecules and the silica gel, it may displace the more weakly adsorbed solvent and interact directly with the silica gel but interact with the other solvent layer by sorption. Alternatively, if solute-stationary phase interactions are sufficiently strong, then the solute may displace both solvents and interact directly with the stationary phase surface. 

The column used was 25 cm long, 4.6 mm in diameter, and packed with silica gel particle (diameter 5 pm) giving an maximum efficiency at the optimum velocity of 25,000 theoretical plates. The mobile phase consisted of 76% v/v n-hexane and 24% v/v 2-propyl alcohol at a flow-rate of 1.0 ml/min. The steroid hormones are mostly weakly polar and thus, on silica gel, will be separated primarily on a basis of polarity. The silica, however, was heavily deactivated by a relatively high concentration of the moderator 2-propyl alcohol and thus the interacting surface would be covered with isopropanol molecules. Whether the interaction is by sorption or displacement is difficult to predict. It is likely that the early peaks interacted by sorption and the late peaks by possibly by displacement. 

HB Hopfenberg, A Apicella, DE Saleeby. Factors affecting water sorption in and solute release from glassy ethylene-vinyl alcohol copolymers. J Membrane Sci 8 273-281, 1981. 

The octanol-water partition coefficient, Kow, is the most widely used descriptor of hydrophobicity in quantitative structure activity relationships (QSAR), which are used to describe sorption to organic matter, soil, and sediments [15], bioaccumulation [104], and toxicity [105 107J. Octanol is an amphiphilic bulk solvent with a molar volume of 0.12 dm3 mol when saturated with water. In the octanol-water system, octanol contains 2.3 mol dm 3 of water (one molecule of water per four molecules of octanol) and water is saturated with 4.5 x 10-3 mol dm 3 octanol. Octanol is more suitable than any other solvent system (for) mimicking biological membranes and organic matter properties, because it contains an aliphatic alkyl chain for pure van der Waals interactions plus the alcohol group, which can act as a hydrogen donor and acceptor. 

The method consists of the retention by sorption of the porphyrins on poly (vinyl alcohol) (PVA) hydrogels. Poly (vinyl alcohol) (PVA) is selected as the polymer of choice for the purification of industrial and medical wastewaters due to its capacity to form physically crosslinked hydrogels with the advantages of non-toxic, non-carcinogenic and biodegradable properties. 

The attractive (80) features of MOFs and similar materials noted above for catalytic applications have led to a few reports of catalysis by these systems (81-89), but to date the great majority of MOF applications have addressed selective sorption and separation of gases (54-57,59,80,90-94). Most of the MOF catalytic applications have involved hydrolytic processes and several have involved enantioselec-tive processes. Prior to our work, there were only two or three reports of selective oxidation processes catalyzed by MOFs. Nguyen and Hupp reported an MOF with chiral covalently incorporated (salen)Mn units that catalyzes asymmetric epoxidation by iodosylarenes (95), and in a very recent study, Corma and co-workers reported aerobic alcohol oxidation, but no mechanistic studies or discussion was provided (89). 

Bartels-Caspers, C., Tusel-Langer, E., and Lichtenthaler, R.N. (1992) Sorption isotherms of alcohols in zeolite-filled silicone rubber and in PVA-composite membranes./. Membr. Sci., 70 (1),... 

The ketone/alcohol ratio in methyl cyclohexane oxidation with PhIO is systematically higher on THPc zeolites than on the homogeneous FePc [63], as shown in Figure 7. This is explained by the authors by a sorption effect, since... 

Recently, the electrochemical behavior saturated alcohols, that is, propargyl alcohol (HCSCCH2OH, PA) [145], benzyl alcohol (C6H5CH2OH, BA) [146] andallylalcohol [147], has been studied at Pd electrodes in an acid medium by cyclic voltammetry, chronoamperometry, and on-line mass spectrometry. For BA, it was observed that the fragmentation of the molecules occurs at potentials in the hydrogen ad-sorption/absorption region of palladium, whereas for PA the adsorbates maintain the C3-chain. On the other hand, the yields of the electroreduction and electrooxidation products for both PA and BA differ from those obtained at Pt [146,148,149]. 

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