Adsorption of liquids

The Freundlich equation proved to be applicable to the adsorption of liquids with only limited ranges of concentration. It was replaced by the Langmuir equation (see later on) and others which had a theoretical basis in the kinetic theory of gases. It is clear that neither the Freundlich nor the Langmuir equation can describe isotherms of the shape shown in Figure 10.5. 

Figure 15.7. Adsorption of liquid mixtures on charcoal. Chloroform + acetone and benzene + ethanol. The ordinate gives the amount of each individual substance that is adsorbed, the abscissa the mol fraction of chloroform (mixed with acetone) or the mol fraction of benzene (mixed with ethanol). (Data gathered by Kipling. Adsorption from Solutions of Non-Electrolytes, 1965).

D.B. Broughton, Production scale adsorption of liquid mixtures by simulated moving bed technology, Sep. ScL Technol. 19, 723-736 (1984-1985). 

One consequence of the curvature dependence of the vapor pressure is capillary condensation, that is the spontaneous condensation of liquids into pores and capillaries. Capillary condensation plays an important role for the adsorption of liquids into porous materials and powders. It also causes the adhesion of particles. The condensing liquid forms a meniscus around the contact area of two particles which causes the meniscus force. ... 

The negative of the enthalpy change for this particular process corresponds to the net heat of adsorption, since the process involves the transfer of the adsorbate from its liquid state to the surface of the adsorbent. (The net heat of adsorption of liquid adsorbate is in turn the difference between the heat of adsorption of the adsorbate vapor and the heat of condensation of the vapor.)... 

Consider now that some adsorption of liquid vapours on the solid surface occurs (Figure 1,34.b), leading to a reduction of its surface energy by a quantity Aliquid surface). For the sake of clarity, we denote by cr< v and W the solid surface energy and the work of adhesion in the absence of adsorption, while pure solid/pure liquid/vapour system held at constant temperature, the solid surface is in equilibrium with a saturated vapour of the liquid at a partial pressure of Psat, the equilibrium values of [Pg.45]

Reaction between neat reactants. The reaction between neat reactants may take place provided that there is present at least on polar molecule [19] as a liquid-liquid or liquid-solid systems. In case of liquid-solid systems the solubilization of solid in liquid phase or adsorption of liquid on solid surface as interfacial reaction takes place. In this type of reaction the effect of microwave irradiation is more pronounced due to the fact that in absence of solvent the microwaves are directly absorbed by the reagent. 

The adsorption of liquid ethyl alcohol on AljOj occurs by H bonding (1108), and without doubt other proton donors are similarly affected. Some part of adsorption from binary solutions (e.g. ethyl alcohol and benzene) is explained by the three-step process alcohol H bonds to the surface, chemisorbs, and then the second component (and more alcohol) physically adsorb on this layer. (See Section 11.2.1 for a discussion of the similar action of water on silicic acid.) Such hydroxyl-covered surfaces are industrially important in cracking and other catalytic processes (2172, 956), and in drying. Plank and Drake (1646) discuss the influence of H bonds in the formation of such materials. 

Figure 11 The adsorption of liquid water on Pd(lll). The binding energy for water on Pd(lll) in the vapor phase is 30kJ/mol. The binding energy for liquid water is —2.5kJ/mol. (Adapted from Ref. [77].)...

SWNTs have nano-sized channels which can facilitate adsorption of liquids or gases. Eswaramoorthy et al. [202] have studied the adsorption properties of SWNTs with respect to methane, benzene and nitrogen. The studies indicate that SWNTs are good microporous materials with a total surface area above 400 m g h In Figure 8.17, we show typical adsorption isotherms for SWNTs. The unique hexagonal packing of the SWNTs in the bundles offers ideal channels, thus allowing the realization of one-dimensional (ID) adsorbates. 

Origin / Industry Sources/Uses Prepared by the chlorination of biphenyl used in the electrical industry in capacitors and transformers used in the formulation of lubricating and cutting oils pesticides adhesives plastics inks paints sealants. Exposure Routes Inhalation of fume or vapor percutaneous adsorption of liquid ingestion eye and skin contact landfills containing PCB waste materials and products incineration of municipal refuse and sewage sludge waste transformer fluid disposal to open areas. 

Fig. 5 Binary surface excess isotherms for adsorption of liquid mixtures (A) benzene (1) + cyclohexane (2) on silica gel and (B) pyridine (1) + -heptane (2) on silica gel and alumina.

Now, we are going to consider another extreme model of surface heterogeneity, when Ay s are not correlated at all. That model has already been elaborated by Rudzihski and co-workers [133,134], for the case of adsorption of liquid mixtures of non-electrolytes on heterogeneous solid surfaces. The relation between the one-dimensional adsorption energy distributions Xi( i) are, for instance such, as shown in Fig. 17. 

Figure 7. Temperature-time dependence for adsorption of liquid from mesoporous adsorbent. 1 - linear program, 2 - quasi-isothermal program.

These heterogeneous reactions are performed between neat reactants in quasiequivalent amounts without any adduct. In the case of solid-liquid mixtures, the reaction implies either solubilization of solid in the liquid phase or adsorption of liquid on the solid surface as an interfacial reaction. 

Stone WJ. 1904. Fatal poisoning due to skin adsorption of liquid shoe blacking (nitrobenzol) with autopsy report. JAMA 43 977-980. 

In summary, inlerfacial processes lead to relatively simple algebraic expressions tor adsorption of liquid films on solid surfaces. In these examples, we have considered the simple ease of long range molecular inlerfacial forces only. The spe-... 

An HPLC experimental technique has been developed to determine the intracrystalline diffusivity and nonlinear adsorption isotherm for the adsorption of liquids in molecular sieve crystals. The application of the experimental technique was demonstrated by the determination of the adsorption isotherms and diffusivities of the five alcohols (ethanol, i-propanol, n-propanol, i-butanol and n-butanol) from aqueous solutions in silicalite crystals. 

Sample Preparation. Samples were prepared by exposing the silica gel, previously dried at 150 °C for 24 h, to either cyclohexane or pentane solutions containing selected amounts of the fluorophore. The solvent was carefully removed under vacuum when required. Complete probe adsorption of liquid-solid samples was verified with absorption spectroscopy. Less than 0.07% of the silica surface was typically covered by the probe. Immediately before data collection, dry samples were evacuated under vacuum at 125-130 °C for 30 min. The total dehydration procedure was sufficient to remove the physisorbed water while leaving the surface silanol functionality intact (12). Selected amounts of oxygen were introduced into a... 

EXPOSURE ROUTES inhalation of fumes percutaneous adsorption of liquid ingestion of contaminated drinking water skin contact eye contact effluents at sites where it is produced or used with other monochloronaphthalenes cooling water discharges leachates fi"om hazardous waste sites effluents from gaseous diffusion facilities and municipal waste incinerators pjTolysis of vinylidene chloride polymer... 

EXPOSURE ROUTES inhalation of fume or vapor percutaneous adsorption of liquid ingestion eye and skin contact... 

EXPOSURE ROUTES derived from coal tar inhalation ingestion adsorption of liquid skin and eye contact... 

---