Cation-exchange Method

At present, the techniques to modify zeolite channels and surface can be classified as three categories that is, cation-exchange method, channel modification, and surface-modification methods. 

N2 adsorption whereas when the exchange degree reaches 58%, the adsorption amount of N2 exceeds that of 02. 

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Shifflet, M. J. and Shapiro, M., Validation of a cation-exchange method to test for residual amounts of a cleaning and sanitizing solution on pharmaceutical process equipment, BioPharm, 51, Jan. 2000. 

Grdinic V and Medic-Saric M (1984) Cation-exchange method for the detection of pyrrole derivatives. Fresenius Z Anal Chem 319, 306. 

Re—O—Re linkage.The complexing of rhenium(iv) with thiourea (L) has been studied in HCl solutions in the presence of tin(ii) by a cation-exchange method, and equilibrium stability constants Pj—P4 for [ReOL4] -t- nCl" [ReOCl L4 -I- nh determined.The complexing of rhenium(iv) with thiocyanate ions in HCl solutions in the presence of SnClj has also been investigated and the formation of a 1 1 Re -SCN" complex confirmed. ° ... 

A hydroxyapatite-bound La complex (LaHAP), prepared by using a cation-exchange method, has been reported to function as an efficient heterogeneous catalyst for the Michael addition of 1,3-dicarbonyls to enones under aqueous or solvent-free conditions. Further application to an asymmetric version by a fluoroapatite-bound La complex catalyst modified with (R,R)-tartaric acid has also been described.171... 

FIGURE 9.13 TEM photographs of aPt/C catalyst prepared by the cationic exchange method (10wt% metal loading). 

The affinity of variously oxidized cellulosic materials for certain basic dyes, notably methylene blue, has long been known. Kenyon and coworkers have recently shown that in the case of nitrogen dioxide oxycelluloses, the methylene blue absorption is a function of the carboxyl group content. Application of the reversible methylene blue method to the determination of carboxyl groups in purified cellulose has been made by Davidson and by Weber, who was able to show good agreement with the cation-exchange methods previously considered as well as with viscosity and osmotic pressure measurements. 

Figure 4b Variation of the carbon monoxide chemisorption vs. metalco fenfo/Pt-SiO catalysts o, cation-exchange method v, impregnation method ...

Fio. 21. Catalytic activities of cadmium-aluminosilicate catalysts for dehydration of isopropanol versus amounts of cadmium in the catalysts. Reaction pressure, 1 atm reaction temperature, 200° G/W, 8.6 hr 1.7 molar ratio of nitrogen to feed , for catalyst prepared by cation-exchange method A, for catalyst prepared by impregnation method. 

Comparison of Figs. 24 and 25 shows the different degree of dispersion of palladium in the two kinds of catalysts one was prepared by the cation-exchange method and the other by the normal soaking method. 

Fig. 24. Palladium on aluminosilicate prepared by cation-exchange method. Palladium content, 1.24 meq/gm.

Fio. 26. Catalytic activity of palladium on aluminosilicate catalyst prepared by the cation-exchange method versus amount of palladium in the catalyst, the reaction being hydrogenation of benzene at 160°. 

Flo. 27. Frequency factor (A) for hydrogenation of benzene, aize of crystallite (Z),) and lattice imperfection rj) of palladium on aluminosilicate catalyst prepared by cation-exchange method versus temperatrue of calcination of the catalyst. Reduction temperature after calcination was kept constwt at 300°. 

The catalytic activity of fine nickel metal is very much reduced and modified when prepared by SHOP or the cation-exchange method, as shown in the previous sections. The partial poisoning of the nickel catalyst with phosphorus compounds brings about almost the same effect. These facts suggest the possible formation of specific and mild active sites of nickel, if nickel metal makes an alloy with phosphorus. 

The formation of nickel(II) chloro complexes in aqueous solution has been studied using a cation-exchange method at 20°C, in a solution of 0.691 M H(C104,C1). The distri-... 

Table A-24 Equilibrium constants for the formation of Th(IV)-chloride and nitrate complexes at room temperature obtained by the cation exchange method.

Nevertheless this paper is helpful to judge hydrolysis constants derived by cation exchange methods. The different pH-dependence of the sorption behaviour of Th(IV) onto different cation exchange materials shows that the evaluation of pH-dependent distribution (sorption) coefficients requires not only the fitting of the forma-tion constants logj (or log ) of the hydroxide complexes formed in solution but also of their equilibrium constants logio A ,m for the sorption onto the cation exchange material (CE) ... 

High pressure steam generators require very good quality feed water. Thus, its overall hardness should be less than 20-30 milligrams/kg, and the silicic acid content less than 30 milligrams/kg. Therefore, water must be chemically purified before it can be fed into the boilers. Water purification system uses the widely accepted sodium cation exchange method with subsequent degasiEcation. Other methods may also be used as required by the quality of source water. 

First, cation-exchanged TSM (M -TSM) was prepared from the parent Na form using a metal nitrate solution by the common cation exchange method, followed by calcination at 200-500 ""C for 3 h (procedure of calc. 1). Al pillaring was then achieved in a mixture of acetone and water (Yamanaka and Brindley 1979). The calcined M" -TSM (1.2 g) was dispersed in a mixed solution of acetone and water (50 ml each) and stirred for 30 min then, 150 ml... 

The phenomenon of ion exchange ie of great utility in the radiochemical separation of Pu. Cationic Pu in dilute, non-complexing, acid solution will readily adsorb on cation resin in the hydrogen or alkali metal form. On the other hand Pu(IV) and Pu(Vl) form anionic complexes in moderately concentrated nitric or hydrochloric acids and BO will adsorb on anion exchange resins. Anion and cation exchange methods are thus both usable to separate Pu. The anion exchange separation is especially valuable in the laboratory because of the simple equipment required, the ease of manipulation, and the excellent decontamination from fission products by the use of redox cycles. 

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