Preparation of cation-exchanged

Preparation of Cation-Exchange Resin. . 535 Isolation of Amino Acids from Deproteinized.. . 535 Samples... 

PREPARATION OF CATION-EXCHANGE RESIN. Amberlite CG-120-H cation-exchange resin is placed in a 600 cm3 beaker about 3 g of dry resin (10-meq capacity) is required for each 0.9 x 15 cm column. The resin is covered with 3N NH4OH, swirled for 30-60 min, and allowed to settle. The NH OH is decanted off, and the process is repeated twice. The resin is then washed with doubly distilled water until it is approximately neutral. 

Sometimes, to achieve a particular objective, the conditions of the correct preparation of cation-exchanged montmorillonites can be neglected. For example, Fe(III)-montmorillonite has been prepared for application in the deep geological repository of high-level nuclear wastes (Manjanna et al. 2009). Acidic pH has been applied, destroying the crystal lattice however, a part of iron(III) ion has been precipitated as oxide and hydroxide, desirable for the sorption of radioactive matter. 

In recent years, many papers have reported the preparation of cation exchange membranes by this method to obtain solid polymer electrolytes for fuel cells. 

M. Seko, Y. Yamagoshi, K. Miyauchi, M. Fukumoto, I. Watanabe, K. Kimoto, T. Hane and S. Tsushima, Membrane composite for preparation of cation exchange membrane, Jpn. Pat. JP 56-37247 (examined application) Cation exchange membrane, Jpn. Pat. JP 56-18605 (examined application) Preparation method of fluorocarbon cation exchange membrane, Jpn. Pat. JP 56-3 7248 (examined application). 

S.D. Alexandratos, M.A. Strand, D.R. Quillen and A.J. Walder, Synthesis and characteristics of bifunctional phosphinic acid resins, Macromolecules, 1985, 18, 829 R.H. Selzer and D.G. Howery, Phosphoric acid ester cation-exchange resins. 1. Synthesis and preliminary characterization, Macromolecules, 1986, 19, 2673 Phos-phonic acid ester cation-exchange resins. 2. Physicochemical characterization, ibid., 1986, 19, 2974 Y. An, T. Koyama, K. Hanabusa, A. Yamada, H. Shirai, J. Ikeda and H. Yoneno, Preparation of cation exchanger based on cross-linked phosphorylated... 

Preparation of Cation Exchanger 7a by Sulfona-tion of Cross-linked Polystyrene (Section 5.1.1)... 

Zu, J., Zhang, J., Sun, G., Zhou, R. and Liu, Z. 2009. Preparation of cation-exchange membrane containing bi-functional groups by radiation induced grafting of acrylic acid and sodium styrene sulfonate onto HDPE Influence of the synthesis conditions,... 

The preparation of cation exchange resin beads with scintillating properties 179... 

M.M. Nasef, H. Saidi and H.M. Nor, Radiation-induced graft copolymerization for preparation of cation exchange membranes A review, Nucl. Sci. J. Malaysia 17, 27 (1999). 

Hwang, G., Ohya, H., Nagai, T. (1999) Ion exchange membrane based on block copolymers. Part III. Preparation of cation exchange membrane. Journal of Membrane Science, 156, 61-65. 

The first examples of cationic exchange of bis(oxazoline)-metal complexes used clays as supports [49,50]. Cu(II) complexes of ligands ent-6a, 6b, and 6c (Fig. 15) were supported on three different clays laponite (a synthetic clay), bentonite, and montmorillonite KIO. The influence of the copper salt from which the initial complexes were prepared, as well as that of the solvent used in the cationic exchange, was analyzed. 

Glucose hydrogenation to sorbitol was carried out on 40 wt% aqueous solution at 100°C, under 80 bar H2-pressure, in the presence of Ru/ACC catalysts prepared by cationic exchange and anionic impregnation. The hydrogenation of 10 wt% aqueous glucosone solution was conducted at 80°C under 80 bar H2-pressure on 2.5 wt%Pd/ACC catalyst in the presence of small amounts of NaHC03 added to increase the pH of reaction medium. Reaction kinetics was followed by HPLC and GC analysis of the reaction medium at different time intervals. 

Wang et al. investigated the catalytic behavior of cation exchange resin supported lanthanide(III) salts of the general structure (31) (Scheme 4.15), prepared from Dowex, Amberlite, Amberlyst and other resins [99]. It turned out that Am-berlyst XN-1010 and Amberlyst 15 complexed best with lanthanides(III). Thus, among others, electrophilic substitution of indole with hexanal and Mukayiama-type aldol reaction of benzaldehyde with ketene silyl acetal proceeded in excellent yields under catalytic conditions (Scheme 4.16). 

Prbpy, 5-(2-MePr)bpy and 5-(2,2-Mc2Pr)bpy have been prepared and characterized. The mer-and /uc-isomers of each complex have been isolated by use of cation-exchange column chromatography as the steric requirements of the R group increase, the percentage of the /uc-isomer decreases. Enantiomers of [Ru(5-Prbpy)3] + were separated on SP Sephadex C-25. Electro-kinetic chromatography has been used to separate the enantiomers of [Ru(104)3] " anionic carboxymethyl-/ -cyclodextrin was employed as the chiral mobile phase additive. ... 

TiY zeolite is one of the few examples where 02 can be formed in zeolites without the need of irradiation. The TiY zeolite is prepared by cation exchange with an aqueous solution of TiCl3. After thermal activation, an EPR signal due to Ti3+ is observed which is destroyed by adsorption of oxygen and a spectrum characteristic of OJ appears at 2.0195, 2.0089, and 2.0031 (279). These results have been confirmed by Kuznicki et al. (280) in a subsequent study on TiY and TiA zeolites. The OJ ion was observed with a signal... 

Ultraviolet Spectrophotometry Pentazocine can be determined in pentazocine hydrochloride tablets by a UV spectral method. The sample is extracted with sulfuric acid, basified, extracted with ether and back-extracted into 1 in 70 dilute sulfuric acid. The absorbance of the solution in 0.5 N H2SO1L is determined at 278 nm and compared to that of the standard preparation. A cation exchange column isolation method can be utilized to determine pentazocine in pentazocine lactate injection. Pentazocine is eluted from the column with methanol 6 N HC1 (1 1). Sample absorbance is read at 278 nm and compared to a pentazocine standard at approximately 120-w.g/ mL (3). 

Step 2. Prepare a cation-exchange column that contains 10 mL of the cation exchange resin, has no bubbles or channels, and is covered with water. Condition the resin by passing 50 mL of 0.1 M HN03 through the column. Discard the effluent. 

In the tenth official proficiency test, MPA in the decontamination sample D2 was not reported by seven laboratories. In most cases, insufficient sample preparation was the reason for the false negative result. The lack of cation exchange, evaporation to dryness of the water phase, and derivatization of the residue may explain why three laboratories missed the chemical. Three other laboratories evaporated the water phase to dryness and derivatized the residue but did not carry out cation exchange. 

The success of the analysis of oligonucleotides is strongly dependent on the choice of the matrix and the preparation of the sample. A major improvement has resulted from the introduction of new matrices specific for the oligonucleotides. An example is 3-hydroxypicolinic acid. [165] Several strategies for sample preparation have been adopted, with the principal goal of eliminating interference from the ubiquitous alkali metal ions a combination of the use of cation exchange columns to replace the alkali metal ions by ammonium and the addition of some ammonium salt to the sample. 

The most important industrial example of cation exchange is the preparation of sodium-montmorillonite/bentonite from calcium bentonite. As seen in Table 2.2, calcium ions have greater affinity to the layer charge than sodium ions, so the calcium-sodium cation exchange must be performed in the presence of carbonate ions. It means that calcium-montmorillonite/bentonite is suspended in sodium carbonate solution. Calcium ions precipitate with carbonate ions, so sodium ions can occupy the interlayer space. This process is known as soda activation of bentonite. The disadvantage of soda activation is that sodium-montmorillonite is contaminated with calcium carbonate. 

The structural parameters of cation-exchanged montmorillonites prepared from calcium-montmorillonite (Istenmezeje) are listed in Table 2.3. As seen in Table 2.3, the basal pacing of monovalent montmorillonite is approximately 1.25 nm, and the water content is approximately 1%. It means that there is one layer of water in the interlayer space. For bivalent montmorillonite, both basal spacing (>1.5 nm) and water content (>10%) are higher, showing two layers of water molecules in the interlayer space. The basal spacing of Pb-montmorillonite is 1.254 nm, which is similar to the value characteristic of monovalent montmorillonite (1.241 nm). However, it does not mean that lead is sorbed on the surface of montmorillonite as monovalent cation since the other parameters that are determined by the distance between the layers (hydration entropy, charge/ion radius value, water content in the interlayer space) lie between the values for bivalent and monovalent cations (Foldvari et al. 1998). 

The Structural Parameters of Cation-Exchanged Montmorillonites Prepared from Calcium-Montmorillonite (Istenmezeje, Hungary)... 

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