Exchange adsorption

As may be gathered, the held of ion-exchange adsorption and chromatography is far too large to be treated here in more than this summary fashion. Refs. 195 and 196 are useful monographs. 

Purification of Antibiotic 66-40 — Dissolve 28 g of crude Antibiotic 66-40 in 100 ml of distilled water and charge to an anion exchange adsorption column (Dowex 1 X2) in the hydroxyl form. Slurry 2,000 g of the resin in water in to a column 2yj in diameter and 36 "high. Elute the column with distilled water at a rate of about 23 ml/min collecting 100 ml fractions and monitor with a conductivity meter and by disc testing against Staphylococcus aureus. 

Adsorption beds of activated carbon for the purification of citric acid, and adsorption of organic chemicals by charcoal or porous polymers, are good examples of ion-exchange adsorption systems. Synthetic resins such as styrene, divinylbenzene, acrylamide polymers activated carbon are porous media with total surface area of 450-1800 m2-g h There are a few well-known adsorption systems such as isothermal adsorption systems. The best known adsorption model is Langmuir isotherm adsorption. 

Organic traps contain isoporous, macroporous, or other specifically designed resins (such as reticulated, cross-linked polystyrene resins devoid of ionic function) and take up organics by a combination of ion exchange, adsorption, and other mechanisms. They typically are installed to precede the DI plant. 

From culture of Streptomyces verticillus by ion-exchange adsorption and column chromatographic purification (on alumina) via the copper complex. 

From culture of Streptomyces capreolus by ion-exchange adsorption. Reference(s) ... 

Chromatography including extraction, ion exchange, adsorption Distillation, volatilization Electrolysis, electrodeposition... 

Understanding the detailed mechanism of ion exchange adsorption may be critical to devising phases that provide resolving power and speed comparable to competing techniques. A review of computer-assisted prediction... 

Steam stripping Air stripping Biological nitrification Chemical oxidation Ion exchange Solvent extraction Biological oxidation (aerobic) Wet oxidation Activated carbon Chemical oxidation Chemical precipitation Ion exchange Adsorption Nano-filtration Reverse osmosis Electrodialysis... 

Molybdenum Cation exchange adsorption Molybdenum Cation exchange adsorption on Chelex-100... 

A variety of preconcentration procedures has been used, including solvent extraction of metal chelates, coprecipitation, chelating ion exchange, adsorption onto other solids such as silica-bonded organic complexing agents, and liquid-liquid extraction. 

The solid-water interface, mostly established by the particles in natural waters and soils, plays a commanding role in regulating the concentrations of most dissolved reactive trace elements in soil and natural water systems and in the coupling of various hydrogeochemical cycles (Fig. 1.1). Usually the concentrations of most trace elements (M or mol kg-1) are much larger in solid or surface phases than in the water phase. Thus, the capacity of particles to bind trace elements (ion exchange, adsorption) must be considered in addition to the effect of solute complex formers in influencing the speciation of the trace metals. 

The influence of the organocation structure on the exchange adsorption becomes evident from the data in table V. 4,4 Bipyridinium cations adsorb two times more energetically (AH s 2j2 kJ Eq ) than do 2,2 bipyridinium cations (AH° = 11 f5 Eq ). The former adapt a planar orientation (dnm = f 26 nm) in contrast to the inclined position of the latter ( qq = 1.4 nm), despite the fact that sufficient surface is available for adsorption in a flat configuration. Smaller enthalpy terms are consistent with smaller electrostatic interaction energies. The reason for the tilting is unknown however. 

The name of zeolites, which originates from the Greek words zeo (to boil) and lithos (stone), was given some 250 years ago to a family of minerals (hydrated aluminosilicates) that exhibited intumescence when heated in a flame. However, the history of zeolites really began 60 years ago with the development of synthesis methods. Commercial applications in three main fields—ion exchange, adsorption, and catalysis—were rapidly developed, the corresponding processes being more environmentally friendly than their predecessors. 

Note that our primary focus is on reversed-phase HPLC (RPLC) since it is the predominant mode for pharmaceutical analysis. Many of these concepts, however, are applicable to other modes of HPLC such as ion-exchange, adsorption, and gel-permeation chromatography. 

Thus, by the mid-1930s the literature described the ion exchange, adsorption, molecular sieving and structural properties of zeolite minerals as well as a number of reported syntheses of zeolites. The early synthetic work remains unsubstantiated because of incomplete characterization and the difficulty of experimental reproducibility. 

Kinetic system, wherein the pathways along the system are moving toward some state of local equilibrium, which in tnm determines the rate of change along the pathway. In the context of a kinetic approach, which is relevant to geochemical processes, dissolntion-precipitation, exchange-adsorption, oxidation-reduction, vaporization, and formation of new phases, are discussed here. 

Boyd GE, Adamson AW, Myers LS (1947) The exchange adsorption of ions from aqueous solutions by organic zeolites II. Kinetics. J Am Chem Soc 69 2836-2848 Brindley GW, MacEwan DMC (1953) Structural aspects of the mineralogy of clays and related silicates. In Green AT, Stewart GH (eds) Ceramics—A Symposium. The British Ceramic Society, Stoke-on-Trent UK, pp 15-59... 

Freeze RA, Cherry JA (1979) Groundwater. Prentice-HaU Englewood Cliffs, NJ Gapon EN (1933) Theory of exchange adsorption in soils. J Gen Chim 3 144-163 Giese RF, Jr. (1982) Theoretical studies of the kaolin minerals Electrostatic calculations. Bull Mineral 105 417 24. 

Sosa, A.V., Ochoa, J. and Perotti, N.L, Modeling of direct recovery of lactic acid from whole broths by ion exchange adsorption. Bioseparation, 9 (2000) 283-289. 

The ease of movement has been expressed by Inglezakis et al. (2004) by die term exchange site accessibility, while the available sites for exchange/adsorption have been expressed by the term exchange site availability. In the framework of the so-called exchange site accessibility concept, an exchange or an adsorption site is characterized by two factors (Inglezakis et al., 2004) ... 

S., "Exchange Adsorption of Strontium on Clay Minerals," U. S. Geol. Surv. Bull., (1964), 1140C. 

Proteins that remain in whey after removing casein from milk are recovered as whey protein concentrates by precipitation with added polyphosphate or other polyvalent anionic compounds, ultrafiltration, ion exchange adsorption, gel filtration, or a combined acid and heat precipitation process. Whey protein concentrates are also manufactured by a combined process involving electrodialysis, concentration, lactose crystallization, and drying (Richert 1975 Morr 1979 Marshall 1982 Anon. 1982 Muller 1982B). 

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