Cation exchange stabilization

Ion Exchange. Crystalline molecular sieve ion exchangers do not foUow the typical rules and patterns exhibited by organic and other inorganic ion exchangers. Many provide combinations of selectivity, capacity, and stability superior to the more common cation exchangers. Their commercial utilization has been based on these unique properties (59). 

Other possibilities for practical application of resin catalysis include some organic reactions involving addition, cyclization, and structural rearrangement. Increased stability and specific control of structure has led to the increased use of cation exchange resins as catalysts. As in the case of cation exchange resins many... 

Stability constants of the complexes formed between Pu(III), Pu(IV), and HSOi, were determined in 1 M acid media by measuring the decrease in extraction (either into TTA-toluene or ion-exchange resin) with increasing concentration of HSO4 in the aqueous solution. Because of very different degrees of extraction for Pu(III) and Pu(IV) and the imposed requirement of 1 M acidity, Pu(IV)-HSOit complexation was studied by TTA extraction, while the Pu(III)-HSOit system was studied by cation exchange. 

One of several studies of this system shows remarkable agreement with the present results. Fardy and Pearson (3) investigated this system by cation exchange at 2 M acidity and ionic strength and reported uncorrected stability constants 8i = 278 (+ 8) and B2 = 6.8 (+0.2) x 103 (K2 24). Assuming the difference in the medium (2 M HClOi, vs. 1 M NaClO, 1.0 M HClOi ) has a minimal effect on the activities of the various complexes,... 

Cation-exchange techniques, stability constant determination of Pu sulfate... 

RG-lyase was purified from Pectinex Ultra SP-L, produced by Aspergillus aculeatus, using anion- and cation-exchange chromatography. The purified RG-lyase differed from RG-hydrolase in pi and pH optimum and stability (Table I). 

The expansion of our knowledge of the structure and function of Na,K-ATPase is reflected in a rapid succession of reviews on Na,K-ATPase genes and regulation of expression [17], subunit assembly and functional maturation [20], the isozymes of Na,K-ATPase [18], and the stability of a subunit isoforms during evolution [21], physiological aspects and regulation of Na,K-ATPase [22], reconstitution and cation exchange [23], chemical modification [24], and occlusion of cations [25]. Other valuable sources are the review articles [26] and recent developments [27] reported at the International Na,K-pump Conference in September 1990. 

Under saturated or very wet conditions, soils tend to have increased amounts of OM. This results in dark colors and dramatically changes the chemical characteristics of a soil. OM increases a soil s sorptive and cation exchange capacities and thus alters the movement and extraction of components present. OM increases ped formation and stability, thus increasing both aeration and percolation, but under saturated conditions, reduction reactions prevail (see Figure 2.12). 

Fig. 20. Test of stability of weak cation exchange monolithic column (ISCO). Conditions column, 50 X4.6 mm i.d., mobile phase gradient of sodium chloride in 0.01 mol/1 sodium phosphate buffer (pH 7.6) from 0.1 to 0.5 mol/1 in 4.5 min and to 1 mol/1 in 6.5 min, overall gradient time 11 min, flow rate 10 ml/min. Peaks Ribonuclease (1), cytochrome c (2), lysozyme (3). The two separations shown in this figure were achieved 503 runs apart...

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