Absorption, distinguished from adsorption

Absorption is distinguished from adsorption by defining it as the filling in of the intergranule void between and within particles. It is thus a filling of three-dimensional space in or between adsorbent particles, whereas adsorption is purely a surface phenomenon. 

The property of adsorption from solutions of a particular solute is in general, apart from the fact that both solvent and solute are adsorbed (see p. 181), complicated by the fact that the adsorbing surface presented to the liquid is not uniform but broken up into a series of fissures or capillaries as is the case with solids such as charcoal and pumice or gels such as those of silica and alumina with the result that true equilibrium between solution and adsorbent may not result until after long periods of time, necessary for the intradiffusion of the solution into the absorbent during which period secondary chemical action may take place. For comparative purposes adsorption as distinguished from absorption or sorption (J. W. McBain, Phil. Mag. xvili. 6,1909) is considered to take place rapidly in solutions as well as in gases (see p. 123). 

Adsorption on solids is an important step in the industrially important process of heterogeneous catalysis. Adsorption, which takes place on the surface (including that of the pores) of the solid, should be distinguished from absorption, which occurs throughout its bulk. The latter is illustrated by the taking up of water by anhydrous calcium chloride. 

The term adsorption is used to describe the process of accumulation at an interface. Adsorption is essentially a surface effect and should be distinguished from absorption,... 

Absorption I) The ability of a porous solid to hold a liquid by cohesion and capillary action 2) Action similar to that of a sponge or blotter in soaking up a liquid 3) As applied to solids, absorption refers to a more or less uniform penetration throughout a solid by any particular component, as distinguished from the existence of a higher concentration of the component at a surface or interface as found in adsorption-, 4) The penetration of liquid or vapor into the solid structure that is, it could be considered a solution with the solid acting as the solvent. 

Adsorption Adhesion of a gas or liquid at a surface resulting in an increased concentration of the gas in the vicinity of the surface to be distinguished from absorption, which occurs throughout the solid or liquid. 

Distinguish absorption from adsorption. When you heat glassware in a drying oven, are you removing absorbed or adsorbed water ... 

Interaction of the Chemical Layer with an Analyte. Interaction with an analyte can take many forms ranging from adsorption - absorption to chemisorption, including the compromise of coordination chemistry. The following types of chemical interactions can be distinguished [274] ... 

Adsorption should be carefully distinguished from absorption. In the latter process a substance is not only retained on the surface, but penetrates to the Interior to become distributed throughout the phase (see Figure 7.2). However, at times, both adsorption and absorption take place side by side and it is difficult to distinguish between the two processes experimentally. The general term sorption (J.W.McBaln, 1909) is implied in such cases. 

The surface atoms of a solid, which are coordinatively unsaturated with respect to the bulk atoms, become saturated thanks to the interaction with molecules of the environment. Adsorption is the process whereby molecules from the gas (or liquid) phase are taken up by a solid surface it is distinguished from absorption which refers to molecules entering into the lattice (bulk) of the solid material. The adsorptive is the material in the gas phase capable of being adsorbed, whereas the adsorbate is the material actually adsorbed by the solid. The solid, which exposes the surface sites responsible for the process is called the adsorbent. In Fig. 1.3 the adsorption process at the surface of a solid material is schematically illustrated. 

Adsorption from solution is important in many practical situations. In dyeing processes, it is necessary to distinguish between adsorption and absorption. Adsorption refers to an excess concentration at the surface, while absorption implies a more or less uniform distribution of the solute in the solid. In these processes the solid phase is known as the adsorbent or absorbent , and the solute (or other species) as the adsorbate or absorbate , respectively. In some cases it may be difficult to distinguish between adsorption and absorptiorr, or, because of lack of data, it may not be known which process is occurring the term sorption is then used. It is probable that adsorption occrrrs at all surfaces. 

Usually adsorption, i.e. binding of foreign particles to the surface of a solid body, is distinguished as physical and chemical the difference lying in the type of adsorbate - adsorbent interaction. Physical adsorption is assumed to be a surface binding caused by polarization dipole-dipole Van-der-Vaals interaction whereas chemical adsorption, as any chemical interaction, stems from covalent forces with plausible involvement of electrostatic interaction. In contrast to chemisorption in which, as it has been already mentioned, an absorbed particle and adsorbent itself become a unified quantum mechanical system, the physical absorption only leads to a weak perturbation of the lattice of a solid body. 

We distinguish this absorptive exchange (Eq. 3-1) from one in which i partitions to an interface. In this new case, the process should be viewed as an adsorption of i to the surface of phase 2 ... 

Sorption Refers to adsorption and/or absorption. Some researchers use the generic term sorption to refer to a natural or artificial process where both adsorption and absorption may be involved or if adsorption and absorption cannot be distinguished. In particular, sorption is a treatment technology that primarily uses adsorption and/or absorption to remove contaminants from water, other liquids, or gases. 

Evidence for ensemble effects in VIIIC/IB alloys has been obtained by examination of carbon monoxide adsorption by infrared spectroscopy. This technique has been applied to the systems Pd-Ag, Ni-Cu, and Pd-Au. It is generally accepted that carbon monoxide may chemisorb in bridged or linear forms, the former providing an absorption band in the region 1900-1950 cm and the other in the region 2000-2050 cm . There may be a distinguishable contribution to the former from CO bonded... 

Sparks CJ Jr (1980) X-ray fluorescence microprobe for chemical analysis. In Winick H, Doniach S (eds) Synchrotron Radiation Research, Plenum Press, New York, p 459-512 Spngberg D, Hermansson K, Lindqvist-Reis P, Jalilehvand F, Sandstroem M, Persson I (2000) Model extended X-ray absorption fine structure (EXAFS) spectra from molecular dynamics data for Ca2+ and Al3+ aqueous solutions. J Phys Chem 104 10467-10472 Sposito G. (1986) Distinguishing adsorption from surface precipitation. In Geochemical Processes at Mineral Surfaces, Davis JA, Hayes KF (eds) ACS Symposium Series 323, The American Chemical Society, Washington, DC, p 217-228... 

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