Solvent carrier exchange system

Preparation of 99.5% Nitrogen-15 by Chemical Exchange between Oxides of Nitrogen in a Solvent Carrier System... 

Figure 3. Exchange column, thermal refluxer, and reflux reactor for the NO-N2O3 solvent carrier system. The parts of the system are discussed in the text. X and Y indicate the positions to which connections are made when two columns are operated in cascade...

Other comparisons in Table VII show that the relative lengths and volumes of the column are somewhat more favorable for the solvent carrier system than for the other two systems. In a previous paper (3i) comparisons were made of the following exchange systems for concen-... 

The systems considered here have, in the carrier fluid, at least one component, which is to be preferentially adsorbed onto or desorbed from particles in simple fixed-bed processes. The number of components in leaching is at least three leaching solvent and two components in solid phase, one of which is to be preferentially extracted. All ion exchange systems have more than two species if we identify each ion as a separate species. Finally, chromatographic processes are concerned with tme multicomponent systems to separate a number of species in the feed fluid sample from one another in the product stream, the carrier fluid. 

Recommended model particle systems are enzymes immobilised on carriers ([27,44,45,47,49]), oil/water/surfactant or solvent/water/surfactant emulsions ([27, 44, 45] or [71, 72]) and a certain clay/polymer floccular system ([27, 42-52]), which have proved suitable in numerous tests. The enzyme resin described in [27,44,47] (acylase immobilised on an ion-exchanger) is used on an industrial scale for the cleavage of Penicillin G and is therefore also a biological material system. In Table 3 are given some data to model particle systems. 

Fractional precipitation (Boyd and Larson, 1969) and ion exchange chromatography (Kleeman and Hermann, 1960) have been reported. The paper chromatographic method for the separation of radioiodine with I, IO3 and IO7 carriers has been reported by a number of investigators (Naeumann, 1965 Cvoric, 1969). Generally, the alcohol-H20-NH3 solvent systems have frequently been used. An example of paper chromatographic analysis is shown in Figure 17.3. 

The versatility of ISEs was enhanced considerably by the introduction of membranes containing neutral ion carriers (ionophores). The first ISE of this type, with a membrane containing valinomycin and selective for potassium ions, was described by Stefanac and Simon in 1966. There are many liquid chemical systems that interact highly selectively with ions through, e.g., ion exchange, ion association, or solvent extraction. Practically useful ISEs based on these systems and on neutral ionophores have been obtained due to the gradual perfection of the technology of plasticized poly(vinyl chloride) (PVC) matrix membranes. 

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