Liquid sorption

Liquid Sorption. If a moist gas is passed through sprays of a liquid sorbent, such as lithium chloride or an ethylene glycol solution, moisture is removed from the air at a rate depending on the vapor pressure difference. This is a function of the absorbent concentration and is maintained at the required level by a regeneration cycle. The regeneration process is continuous and is achieved by allowing a percentage of the chemical into the exhaust-heated air. 

The process of diffusion in which molecules are transferred from the gas phase into a solid or liquid sorption medium. 

The methods described in this chapter can be transferred to liquid sorption processes with slight modifications. The example of concentrated salt solutions and water absorption is described by Kessling [6],... 

The complex sorption behavior of the water in amine-epoxy thermosets is discussed and related to depression of the mechanical properties. The hypothesized sorption modes and the corresponding mechanisms of plasticization are discussed on the basis of experimental vapor and liquid sorption tests, differential scanning calorimetry (DSC), thermomechanical analysis (TMA) and dynamic mechanical analysis. In particular, two different types of epoxy materials have been chosen low-performance systems of diglycidyl ether of bisphenol-A (DGEBA) cured with linear amines, and high-performance formulations based on aromatic amine-cured tetraglycidyldiamino diphenylmethane (TGDDM) which are commonly used as matrices for carbon fiber composites. 

Heat pipes can easily be implemented inside sorption storage vessels. They are the most convenient thermal control devices for the solid and liquid sorption machines due to its flexibility, high thermal efficiency, cost-effectiveness, reliability, long operating life, simple manufacturing technology. 

Fig. 2. Kinetics of liquid sorption in 10 replications using samples cut from the same microporous composite sheet. The sorbent particles were Sephadex microspheres (Example shown in Fig. 1)...

The above results indicate that Eq. 14 may be general for liquid sorption by crosslinked polymer networks, i.e. the volume, S, of liquid sorbed per gram of crosslinked polymer increases linearly with the cube root of the average number, X, of backbone atoms in the segments between crosslink junctions. The constants... 

These studies of liquid sorption by poly(Sty-co-DVB) particles enmeshed in PTFE microfibers have shown that an adsorption parameter, a, characteristic of the molecular structure of a sorbed liquid with respect to that of the monomer unit in the polymer, can be determined with good precision (+1 in the third significant figure) by measuring the weight of sorbed liquid per unit weight of enmeshed particles. These adsorption parameters appear to be of fundamental scientific value and therefore potentially useful in understanding natural phenomena in which adsorption plays an important role. 

Like layer silicates, the porous palygorskite can also be organophilized. X-ray studies, however, do not reveal any structural changes in the organocomplexes, since cationic surfactants are adsorbed only on the external surfaces. The amount of surfactant bound by ion-exchange adsorption and the extent of organophilicity can be quantified by the liquid sorption studies and microcalorimetry [19-21]. 

Figure 10 shows basal spacing (dn) for the liquid sorption equilibrium systems descri-... 

Liquid sorption on palygorskites and their hydrophobic derivatives... 

We shall next examine how these surface structural characteristics affect liquid sorption in the alcohol(l)+benzene(2) mixtures. Figure 17 shows the excess isotherm determined on palygorskite. In the case of methanol(l)+benzene(2) mixtures the isotherm is of type II, indicating that methanol is preferentially adsorbed and penetrates into the micropores of the zeolite-like channels as well. With increasing the number of carbon atoms in the alcohol, preferential adsorption is repressed and isotherms of types III and IV are obtained. The reason for this is that, due to steric hindrance, alcohols of larger size cannot enter the micropores. 

Similarly to the case of the hydrophobic clay minerals described above, isotherms determined on HDP-palygorskite are S-shaped (Fig. 18). Surface modification by HDP" -cations has a double effect. On increasing the amount of HDP-cations the liquid sorption capacities decrease, since the micropores get clogged. On the other hand, the polarity of the surface decreases and the azeotropic composition indicates the displacement of the alcohol on the surface[50]. 

Sorptivity or liquid sorption coefficient is theoretically expressed as follows [32] ... 

Liquid Sorption. Liquid sorption measurements were performed gravlraetrlcally on polymer A In methanol-water and methanol-Isooctane solutions. The results are plotted In Figs. 11 and 12. In Fig. 11, a linear tle-llne was drawn through the solvent uptake data points for the pure liquids. It appears that the amount of methanol (or water) absorbed by the polymer Is linearly proportional to the mole fraction of methanol In the solution. However, proof of this assertion requires the Independent measurement of the species dissolved In the polymer. In other words, the partitioning of the solvents within the polyurethane Is not known. In contrast to the aforementioned behavior, positive deviations were observed from the linear tle-llne In Isooctane-methanol solutions. This Indicates that an excess of one liquid, and of possibly both, was sorbed by the polymer (Fig. 12). These results also demonstrate that methanol Is much more compatible with the polyurethanes than water (I.e., methanol Is absorbed to a much greater degree In the polymer than water). 

Figure II. Liquid sorption of polymer A in methanol-water solutions at 60° C as a function of mole fraction of methanol.

Vapor pressure Partitioning between phases solubility of a gas in a liquid sorption of a solute in a fluid onto a sorbent Chemical reaction equilibrium Electric charge Phase change solid/liquid liquid/gas Diffusivity Ionic mobility Molecular size and shape... 

The synthesis of Pd-hexadecylammonium montmorillonite (HDAM) samples was performed by the in situ reduction of Pd(OAc)2 in the interlamellar space, with a bulk composition of ethanol toluene = 5.95. The method of preparation was designed according to preliminary liquid sorption and XRD measurements. At small ethanol concentrations in toluene, the selective interlamellar sorption of ethanol was established, which ensured the diffusion of Pd ions from the bulk phase to the interlamellar space, where reduction to Pd" took place. Samples of 2.5, 4.2, 6.5 and 10.2% Pd loadings were synthesized and characterized by N2 adsorption, TEM, XRD and SAXS measurements. A detailed description of the preparation method and instrumental analysis has been published recently [10]. 

Advantages of SPME to traditional extraction methods should promote advances in the field of herbicide chemistry. However, SPME has some limitations, such as analyte carryover, fiber damage at extreme pH, salt-related problems, and low sensitivity in some complex soil samples. Advancements are being made in the refinement of the SPME technique. The HPLC/SPME interface has then been improved, and new mixed phases based on solid/liquid sorption (e.g., CW-DVB and PDMS-DVB) have been developed in recent years for the analysis of compounds by HPLC. A modified accessory to the HPLC system, called in-tube SPME, was developed. This device aspirates and dispenses samples from vials with the syringe in the inject position and then desorbs with aspirated solvent in the load position. Returning the valve to the inject mode will transfer analytes to the analytical column. ... 

Some of the variety of techniques described In the literature have resulted in the commercialization of modules independent of the chromatograph and providing it with different degrees of automation. Such modules are based on extraction (both liquid-liquid and solid-liquid), sorption (adsorption, ion exchange), vaporization, filtration (simple or through molecular sieves) or dialysis processes, or on chemical derivatization techniques. Some of these preliminary operations are better suited to HPLC, others to GC and the remainder equally to both. Only those involving the reduction of human Intervention to some extent are described here. This is a wide topic, so a comprehensive treatment is beyond the scope of this book. Below are described some representative examples of both HPLC and GC. Many of the systems described are based on the continuous separation systems dealt with in Chapter 4, devoted to the automation of sample treatment. The foundation of continuous and segmented flow analysers plays a major role in this context. 

In summary, there is a lack of information on the separate uptake of methanol and water in Nafion composite membranes which preclude any conclusion about the partition of methanol, while the effect of the filler on the liquid sorption, as noted in the case of the uptake of pure methanol (Sect. 6.5.1), seems to be complex and not easy to assess. 

Solvent extraction, solid-liquid sorption, ion exchange, and precipitation methods are commonly used for the separation or preconcentration of precious metals from various matrices. 

Fig. 2. Examples of Freundlich isotherms of ionic liquid sorption on agricultural soil (AGl). ( ), 1-butyl-3-methylimidazolium ( ), l-hexyl-3-methylimidazolium and (A), 1-butyl-3-ethylimidazolium entities. Values are the means of two determinations. Reprinted from ref. [12] with the permission of CSIRO PUBLISHING (http //www.publish.csiro.au/...

Freundlich isotherm coefficients determined by linear regression of data for ionic liquid sorption on agricultural soil... 

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