Ion-exchange Data Research Articles

Application of a simple thermodynamic model to various ion exchange data

Abstract The three-parameter model introduced earlier has been applied to a strong-acid resin, a strong-base resin, a complex-forming resin and a liquid cation exchanger. In all cases the model gives a satisfactory fit to the experimental data. Using empirical relations between model parameters and divinylbenzene or water content a considerable data reduction is obtained.

Synthesis of cobalt containing ZSM-5

Cobalt-ZSM-5 is prepared by addition of various cobalt containing substrates to ZSM-5 synthesis gels. The existence and homogeneity of intrazeolitic cobalt is established from XPS and electron microprobe analyses. Variations in the synthesis gel composition were found to influence the amount of intrazeolitic cobalt in the ZSM-5. In at least one preparation, the ion exchange data are consistent with cobalt occupying framework sites. Cobalt-ZSM-5 exposure to 3 atm. H 2 at 470°C and 21 atm. rsol|CO/H 2 (1:1) at temperatures to 470°C did not reduce the cobalt to the zero-valent state and did not cause the cobalt to migrate to the outer surface of the ZSM-5.

Shale Oil Denitrogenation with Ion Exchange

Abstract The nitrogen-containing aromatics normally found in crude retorted shale oils have been shown to be involved in reactions leading to the deposition of insoluble gums and sediments. These nitrogen-containing compounds must be removed in order to permit the effective utilization of the shale oil product. A process is proposed in which the nitrogen-containing compounds found in raw shale oil are removed by mild hydrodenitrogenation followed by resin ion exchange. Ion exchange data from experimentation involving six jet fuel (15M-271°C) and diesel fuel (271–343°C) boiling point cuts are presented. Amberlyst A-15, a macroreticular, strongly acidic, cation exchange resin is used in this study. Three types of experiments were performed: batch sorption equilibrium experiments, batch sorption kinetics experiments, and dynamic ion-exchange column performance tests. The Langmuir isotherm was found to describe the equilibrium sorption behavior of the shale oil/ion-exchange resin system fairly Well. The sorpt...

Thermodynamics of mixing in NaK β-aluminas

The activities of the components in the pseudo-binary NaK β-alumina system have been calculated from equilibrium ion-exchange data. Using data from exchanges with molten nitrate, chloride, and iodide salts, the results indicate that this system shows negative deviations from ideal mixing. A model involving preferential “ion pairing” of Na and K ions gives a good fit to the experimental data. Two maxima in the excess stabilities are found at compositions lying close to those which have been shown to exhibit the lowest ionic conductivities in the system. It is suggested that the “mixed-alkali” effect in NaK β-alumina is strongly related to the presence of cation order, and that the driving force for order results from reduction of nearest-neighbor cation repulsions.

A useful method for summarizing data in ion exchange. I. Some illustrative examples

Abstract The following equations has been applied to ion exchange equilibria: Y = yAxA + yBxB + BxAxB where Y is the quantity studied, xA and xB are the fractions of the two components in the binary mixture considered, yA and yB are values of the quantity Y for pure A and B, while B is a quantity taking care of deviation from additivity. The following systems from the literature have been treated: 1. (1) (C2H5)4N+−H+ exchange, as well as water uptake during exchange on KRSx8. 2. (2) Water and methanol (MeOH) uptake from their mixtures by the resin AV-17x8 in sulfate form. 3. (3) Cs+ − Na+ exchange on Dowex 50 of various crosslinkings. 4. (4) Ag+ −Na+ exchange on Dowex 50x8 and x16. It is found that all ion exchange equilibria as well as water uptake during exchange can be fitted with above equation with B = O or B = constant. The uptake of water and MeOH from their mixtures seems to require more complicated expressions. It is shown that for B = 0 the systems behave as regular solutions. It is possible to fit the ion exchange equilibria between Cs+ and Na+ with only four constants, giving a reasonably good fit both with composition and degree of crosslinking from 2 to 16% DVB.

A tabulation and evaluation of ion exchange data on smectites

An extensive search of the literature was made for ion exchange data on smectites. The data, in the form of ion exchange equilibrium constants and free energies of exchange, have been tabulated and evaluated. Equilibrium constants describing monovalent-monovalent and monovalent-divalent types of exchange for the same reaction on the same type of smectite were found to differ by as much as an order of magnitude. While some of the difference can be attributed to variance in experimental procedures, much of the difference appears due to differences in charge densities and effective field strengths of the smectites, which are in turn related to the amount and type of substitution on intercrystalline octahedral and tetrahedral sites.

Simplified evaluations of mass transfer resistances from batchwise adsorption and ion-exchange data. 1. Linear isotherms

Simplified evaluations of mass transfer resistances from batchwise adsorption and ion-exchange data. 1. Linear isotherms

Simplified evaluations of mass transfer resistances from batchwise adsorption and ion-exchange data. 2. Nonlinear isotherms

Simplified evaluations of mass transfer resistances from batchwise adsorption and ion-exchange data. 2. Nonlinear isotherms

Copper(II) complexes of hydrazides

Abstract The Cu(II) complexes of three hydrazides of aspartic and glutamic acids have been obtained and studied using electronic IR and EPR spectra, DTA, magnetic susceptibility measurements, extraction, ion exchange and elemental analysis data. It was found that depending on the reaction conditions two types of complexes are obtained, with M:L ratios 1:1 and 1:2, copper(II) being six-coordinated in both. The 1:1 complexes include one hydrazide molecule and three inorganic ligands. When CuCl 2 is used as the initial Cu(II) salt, one Cl − and two OH − are coordinated at pH 6.5–7.0 (resp. two H 2 O molecules at pH 3.0–3.5), while using CuSO 4 only OH − , resp. H 2 O are coordinated together with the hydrazide. In the 1:2 complexes two hydrazide molecules are coordinated, no other ligands being present in the coordination sphere. A possible structure of the complexes, consistent with all the experimental data is proposed and discussed.

On the properties of solid and liquid ion exchangers—VII: A simple model for the formation of mixed micelles applied to salts of dinonylnaphtalene sulfonic acid

In previous papers in this series it was found[1,2] that ion exchange and water sorption data for dinonylnaphtalene sulfonic acid (HD) in various solvents could be fitted by the expression Y=y 1 X ̄ +y2(1- X ̄ )+y′ 2 X ̄ (1- X ̄ ) Y is the property studied and y i the same property related to three kinds of micelles, those corresponding to the pure salts ( y 1 and y 2) and mixed micelles containing both ions ( y′ 3). X is the equivalent fraction of metal ion in the organic phase the H +Me 2+ exchange being studied. In the present paper it is shown that if it assumed that the distribution of ions over the three kinds of micelles is random the quantities in eqn (1) can be given a simple physical interpretation.

On the properties of solid and liquid ion exchangers—VIII: Potassium-hydrogen and calcium-hydrogen exchange in dinonylnaphthalene sulfonic acid dissolved in heptane-isooctanol mixtures

Ion exchange and water sorption data for the systems (K,H)D and (Ca,H)D (D = dinonylnaphthalene sulfonic acid) in heptane-isooctanol mixtures can be described by a simple equilibrium model for formation of mixed micelles. This model gives the following relation between the experimental quantity Y and the corresponding quantities y i relating to the two pure micelles and the mixed micelle Y=y 1X 2+y 2(1- X ̄ ) 2+2y 3(1- X ̄ ) X = equivalent fraction of metal ion in the organic phase. This equation can be identified with the relation Y=y 1 X ̄ +y 2(1- X ̄ )+y′ 3 X ̄ (1- X ̄ ) used to fit experimental data Y( X) . The quantity y 3 is computed from y 3= (y 1+y 2+y′ 3 2 Both extraction and IR data show that isooctanol forms complexes with the sulfonate partly blocking the ion exchange process.

Stability of metal uncharged ligand complexes in ion exchangers. Part 2.—The copper+ethylenediamine complex in montmorillonite and sulphonic acid resin

The thermodynamic stability of the copper+ethylenediamine complex is determined in montmorillonite and a macroreticular sulphonic acid resin using ion exchange data and the complex formation function. Both methods are in excellent agreement and correspond to an increase in the overall stability constant of 103 for montmorillonite and 101·3 for the resin. The stepwise formation constants text-decoration:overlineK1text-decoration:overlineK2 of the ion exchanged complex are 1011·6 and 1011·5 for montmorillonite and 1011·65 and 109·7 for the resin, as compared with values of 1010·7 and 109·3 for the bulk solution. Some tentative interpretation is offered in terms of a decreased ligand solvation in the ion exchanger.

A nepheline-alkali feldspar geothermometer

A nepheline-alkali feldspar geothermometer has been developed which is based on the thermodynamics of an Na—K exchange reaction between nepheline and alkali feldspar. The activities are formulated in terms of site occupancies, and the regular solution model is used to represent non-ideal mixing of the cations on each site. The distribution of Na and K on the alkali sites in nepheline is calculated from published nepheline-brine ion-exchange data. The standard Gibbs energy of the geothermometer reaction is calculated from experimental data on coexisting nephelines and alkali feldspars (Hamilton and MacKenzie, 1960, 1965). The geothermometer is applied to nepheline syenites from the Precambrian Igdlerfigssalik intrusion, S.W. Greenland, and gives temperatures which suggest that nepheline and alkali feldspar continue to equilibrate with cooling after they crystallise from the magma.

Preparation of some new inorganic ion exchangers

The tellurates of titanium and chromium were investigated. The method of preparation of titanium tellurate is given. Chromium tellurate could not be obtained by the usual method. Based on various experiments, the composition, solubility and ion-exchange data of amorphous titanium tellurate were obtained.

Automated Enzymatic Determination of L-Lysine in Grain

Abstract An accurate and precise automated method has been developed for the determination of lysine in grain hydrolysates. The enzyme L-lysine decarboxylase specifically catalyzes removal of the carboxyl group from L-lysine, producing an amine and carbon dioxide. This reaction has been automated. The carbon dioxide produced was selectively dialyzed into a stream of carbonate with phenolphthalein by a dialysis block containing a carbon dioxide gas dialysis membrane. Ground samples of grain (250 mg) were hydrolyzed 20 hr in 25 ml 6N HC1 at 110°C Aliquots were evaporated to dryness under nitrogen with low heat. The samples were redissolved in carbon dioxide-free water and the enzyme was suspended in pH 6.5 phosphate buffer. Analyses were made at 30/hr with a sample-to-wash ratio of 4:1. A standard curve with a range of 0 to 90 ppm lysine was expanded to full scale on the recorder. From the comparative height of each sample peak vs. the standard curve, the per cent lysine in the original sample can be calculated. Repeated analyses on 15 samples, 5 each of corn, mungbeans, and soybeans, by the automated method showed that the precision was good, and the results were in good agreement with classical ion exchange data. The automated method for lysine in corn has been used in our laboratory to analyze 1500–2000 corn samples each year for the last 5 years.

Etude des solutions solides des néphélines (Na, K)AlSiO 4 et (Na, Rb)AlSiO 4

Ion exchange equilibrium of nepheline solid solutions (Na, K)AlSiO 4 and (Na, Rb)AlSiO 4 with hydrothermal solutions has been studied at 600°C and 2000 bars. The behaviour of dilute solid solutions was specially investigated. Na-Rb ion exchange data can be represented satisfactorily by a model taking into account the existence of two different sites in the structure of nepheline. At 600°C Rb atoms substitute almost exclusively for Na atoms situated in the larger sites. On the other hand, this model only partially applies to Na-K ion exchange equilibrium. Finally, the importance of the ion exchange data concerning extremely dilute solutions to calculate activity-composition diagrams is emphasized with special reference to the nepheline solid solutions.

Ion exchange of the transition metal ions Mn2+, Co2+, and Ni2+ in synthetic zeolites NaX and NaY

Abstract The exchange of Mn2+, Co2+, and Ni2+ in zeolites X and Y has been studied. At 25 °C, these metal ions cannot replace sodium ions present in the network of smaller cavities of both the zeolites. It is possible to describe the ion exchange data by a mathematical equation. The mathematical model assumes two groups of active sites in the supercages.

Molecular basis for some physical properties of alginates in the gel state

Alginate is a binary linear heteropolymer containing 1,4-linked β-D-mannuronic and α-L-guluronic acid residues in varying proportions. The monomers are arranged in a blockwise fashion along the chain; it contains the two homopolymeric blocks (MM and GG) together with blocks of the alternating sequence (MG) in the same molecule. Data from light scattering and viscometric experiments show that their relative unperturbed dimensions increase in the order: MG-blocks < MM-blocks < GG-blocks. Ion exchange data show that GG-blocks are characterized by a selective binding of calcium ions in solution, a strong autocooperative binding of calcium between the chains in the gel state, and hystrisis due to a slow dissociation of the cooperatively-formed functions between the chains. The two other blocks have much lower selectivity for calcium ions, no autocooperative binding mechanism and no detectable hysteresis. The mechanical strength of calcium alginate gels is mainly due to junctions formed by the GG-blocks. the modulus of rigidity of gels formed by different cations is directly dependent on their ability to bind to the polyuronides by a cooperative inter-chain binding mechanism.

Ion-exchange in analytical chemistry: problems and prospects

Abstract

Behavior of Chromate in Drilling Fluids Containing Chrome Lignosulfonate

Abstract The effect of chrome lignosulfonate dispersants on the rate of reduction of added chromate in drilling fluids was determined by polarographic analysis. Analyses were made after aging the fluids at ambient and elevated temperatures. A study was made of the comparative corrosion rates of mild steel in chrome lignosulfonate solutions before and after aging. From the data obtained, it was inferred that chromate, in the presence of chrome lignosulfonate, is reduced and complexed with the lignosulfonate molecule. The data show that the reaction is quite slow at room temperature, but is accelerated at elevated temperatures. The rate of reaction is also dependent on the lignosulfonate concentration. The corrosion rate studies showed that the corrosion protection provided by the added chromate is protection provided by the added chromate is dissipated after aging. It is concluded that the acceleration of corrosion rates often observed at very low chromate concentration is obviated by the presence of lignosulfonate. The reason for this is presence of lignosulfonate. The reason for this is that chromate in very low concentrations is rapidly reduced in this environment, particularly at slightly elevated temperatures. Introduction Since the advent of chrome lignosulfonates as dispersants for water-base drilling fluids about a decade ago, chromium has served an important function in the control of these fluids. In addition to the chromium present in the lignosulfonate molecule, soluble chromates are added to drilling muds as standard practice to improve their thermal stability. The addition of chromates to aqueous systems, generally for corrosion protection, is a practice of long standing. It has been reported in practice of long standing. It has been reported in the past, however, that chromates intensify corrosion if added in insufficient quantities. Several authors have investigated various aspects of metal lignosulfonates in drilling fluids. Jessen and Johnson studied metal exchange effects of ferrochrome lignosulfonates on sodium and calcium clays. More recently, X-ray and ion exchange data obtained by McAtee and Smith led them to suggest two mechanisms for the action of metal lignosulfonates. In view of its importance, a study of some additional aspects of chromium in drilling fluids was undertaken. It is known that chromate, a strong oxidizing agent, will ultimately oxidize chrome lignosulfonates in drilling mud systems. Polarographic analyses of chrome lignosulfonate Polarographic analyses of chrome lignosulfonate solutions were, therefore, made to determine how fast this reaction occurs. To clarify the results of these analyses, some ultracentrifugation ultrafiltration experiments were undertaken. Finally, some comparative corrosion rates of aged and heated chrome lignosulfonate solutions were made to determine if the reducing properties of the chrome lignosulfonates would alleviate the corrosion intensification effects reported for low concentrations of chromate in aqueous systems. EXPERIMENTAL The following experimental procedures were used.Polarographic analysis of modified (chrome) lignosulfonate (MLS) solutions and muds before and after heating, with and without added chromate.Ultracentrifugation (32,000 × g) and ultrafiltration (0.45-micron filter) of MLS solutions and muds. Chromium analysis of supernatants and solids.Comparative corrosion rates of MLS solutions and muds as determined by a corrosion rate meter before and after aging and heating. POLAROGRAPHIC ANALYSES POLAROGRAPHIC ANALYSES A polarograph was used to determine the half-wave potentials for chrome lignosulfonate solutions with potentials for chrome lignosulfonate solutions with and without bentonite. The values obtained are shown in Table 1. SPEJ P. 140