Adsorbent accumulation

GLATZ ET AL. Adsorbent Accumulation of Pollutants TABLE I. Identification of Solid Sorbents 93... 

The second possibility is that the interface between the two phases is impervious to the component (or components), in which case the component adsorbs (accumulates) at that interface. The amount of adsorbed species depends, in a complex way, on the interactions between the adsorbate molecules, between the adsorbate and the interface, and between all the other species competing for the interfacial area. This gives rise to different adsorption isotherms. The simplest is the Langmuir isotherm in which adsorbing species behave as a 2-D ideal gas and do not influence each other (Aflads is independent of occupancy). The concentration of adsorbed species Csx is linked by the adsorption equilibrium constant K to concentration Cs of the species in the gas (or solution). 

The Brunauer-Emmett-Teller equation governing multilayer adsorption shows inflections above monolayer saturation as the adsorbate accumulates on a surface over an extended interval. Heller (1966) factored in the time variable ... 

Provides new interfaces to adsorb/accumulate substances detrimental to membrane performance... 

Electrochemical quartz crystal microbalance. To monitor adsorbate accumulation on catalyst surfaces from formic acid electrooxidation and advance mechanistic understanding, an electrochemical quartz crystal microbalance (EQCM) can be used to simultaneously measure current and mass [22, 66, 81-83]. The dampening of the vibration frequency (A/) of an AT-cut 9 MHz piezoelectric crystal is directly proportional to mass accumulation (Am) on the catalyst surface through the Sauerbrey equation (A/ = —/o 2(jUqPq) Am/A) [84], where /o is the base... 

A comprehensive summary of all reactions with coupled chemical steps and adsorbed/accumulated species on the electrode surface was elaborated in 1977 [103]. The classification given there enables chemical and adsorption processes to be verified and evaluated on the basis of this technique. 

The heatless adsorber (pressure suing) The method of operation shown in Fig. 11.40 for removing a vapor from a gas under pressure uses mechanical work of compression instead of heat to regenerate the adsorbent [92], Wet gas under pressure passes through four-way valve 3 into adsorber bed 1, and the dry gas leaves at the top. A portion of the product gas is passed through valve 4 and at a lower pressure into bed 2 to evaporate the adsorbate accumulated there. It... 

These surface active agents have weaker intermoiecular attractive forces than the solvent, and therefore tend to concentrate in the surface at the expense of the water molecules. The accumulation of adsorbed surface active agent is related to the change in surface tension according to the Gibbs adsorption equation... 

If < 1, then binding is anticooperative, for example when an electrically charged particle adsorbs at an initially neutral surface the accumulated charge repels subsequent arrivals and makes their incorjDoration more difficult [58]. 

The mechanism of poisoning automobile exhaust catalysts has been identified (71). Upon combustion in the cylinder tetraethyllead (TEL) produces lead oxide which would accumulate in the combustion chamber except that ethylene dibromide [106-93-4] or other similar haUde compounds were added to the gasoline along with TEL to form volatile lead haUde compounds. Thus lead deposits in the cylinder and on the spark plugs are minimized. Volatile lead hahdes (bromides or chlorides) would then exit the combustion chamber, and such volatile compounds would diffuse to catalyst surfaces by the same mechanisms as do carbon monoxide compounds. When adsorbed on the precious metal catalyst site, lead haUde renders the catalytic site inactive. 

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) ai e toxic compounds of anthropogenous origin, able to accumulate in tissues of alive organisms and to cause different diseases. These compounds ai e the most dangerous for aquatic ecosystems as they easily adsorb in sludge and ai e included in food chains of biota. Humans consume PCBs and OCPs mostly with fish. 

Columns can be washed with solvents and solvent combinations suitable to remove adsorbed contaminants. When considering the adsorption of analytes, think not only of the diol functionality, but also of the adsorption to residual silanols. Often, the injection of small amounts (500 /d) of dimethyl sulfoxide removes contamination that has accumulated on the column. Aqueous solutions of sodium dodecyl sulfate, guanidine hydrochloride, or urea are compatible with Protein-Pak columns. 

Part (a) is the driving force for the adsorption. If only (a) were present, adsorbed chains would lie flat on the surface. Parts (b) and (c) are the opposing forces (b) accounts for the entropy loss of a bond on the surface as compared to the solution, (c) represents the separation into a concentrated surface phase and a dilute solution. Part (d) arises from polymer-polymer, solvent-solvent and polymer-solvent interactions, which usually favour accumulation of segments. At equili-... 

As revealed by IR-spectroscopy, the attachment of the polymer proceeds via acylation of aminopropyls absorbances of both amides (1650 cm-1) and esters (1740 cm-1) contribute to the spectrum of polyacrylate-coated aminopropyl-Aerosil (specific surface area 175 m2/g) [55], During the reaction, the accumulation of p-nitrophenyl ester groups in the support is accompanied by the liberation of p-nitrophenol into the contacting solution. Thus, the evaluation of the conformational state of adsorbing macromolecules can be performed by the simultaneous study of both processes by UV-spectroscopy as shown in Fig. 7. Apparently, at... 

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