Ivan J. Gal

Isosteric heats of n-hexane sorption in ion-exchanged NaX containing Co2+, Ni2+, Zn2+, and Cd2+

Abstract Sorption—desorption isotherms of n -hexane have been measured at 288 and 298 K in zeolites M x Na 87-2 x X (M = Co, Ni, Zn, Cd) and the corresponding isosteric heats have been obtained. The effect of cations on isosteric heats is highly pronounced at low cowerage, being different for each particular cation. An attempt is made to explain the large differences in those heats in terms of cationic size, charge, electronic configuration, and location in the lattice.

Sorption of n-hexane on cation-exchanged X and Y zeolites containing some divalent transition metal ions

Abstract Sorption isotherms of n-hexane on ion-exchanged X and Y zeolites of the type M x Na 87-2 x X and M x Na 56-2 x Y (MCo, Ni, Zn, Cd) have been measured and interpreted in terms of the Dubinin —Radushkevich equation. The substitution of sodium ions with spin-paired Zn 2+ and Cd 2+ ions causes a decrease in sorption, whereas the substitution with spin-free Co 2+ and Ni 2+ increases the sorption.

Formation constants of chlorocadmium(II) and cadmium dichloride in aqueous melts of calcium dinitrate and calcium dinitrate–potassium nitrate

Formation constants of [CdCl]+ and CdCl2 in aqueous melts of Ca[NO3]2·xOH2 and Ca[NO3]2·K[NO3]·xOH2(x= 3.5–7) have been determined at 50, 65, and 80 °C from e.m.f. measurements in suitable concentration cells. The results are discussed in terms of a quasi-lattice structure of aqueous melts, and a model is proposed which predicts the dependence of thermodynamic data for [CdCl]+ formation on the temperature and water content of the molten salt.

Thermodynamics of metal complex formation in aqueous melts of calcium dinitrate–ammonium nitrate. Part I. Cadmium(II) chlorides

The formation constants of [CdBr]+ and CdBr2 in melts of Ca[NO3]2·a[NH4][NO3]·xH2O (a= 1.5—1 1.5,x= 0—8), in the range 323–433 K, have been determined from e.m.f. measurements in suitable concentration cells. The results are discussed in terms of a previously developed model based on the quasi-lattice concept of aqueous melts.

Calculation of phase equilibria of ternary additive molten salt systems with a common anion

Phase diagrams for ternary additive systems LiF + NaF + KF, LiF + NaF + CaF2, LiF + NaF + SrF2 and NaF + KF + SrF2 have been calculated a priori using a set of readily available physical parameters for each component. The method of calculation is based on a simple ion-interaction model developed for binary molten salt systems and now extended to ternary additive salt mixtures. Calculated and experimentally derived phase diagrams are compared and discussed.

Calculation of phase diagrams of binary salt mixtures with a common anion

In order to calculate excess chemical potentials of the components in binary molten salt mixtures, a simple model is proposed which requires three physical parameters for each salt: the crystal lattice energy, the latent heat of melting and the sum of the ionic radii. The model has been used to calculate the liquidus temperature for various compositions of the binary system. Calculated and experimentally determined phase equilibria for the following systems are compared: LiF–KF, LiF–NaF, NaF–KF, LiCl–KCl, NaCl–CsCl, LiNO3–NaNO3, CaF2–MgF2, LiF–CaF2, NaF–CaF2 and NaCl–SrCl2.

Isotopic exchange kinetics of zinc ions in Zn-A zeolite

The isotopic exchange kinetics of Zn2+ ions in hydrated Zn-A zeolite of composition Zn5·55Na0·90(AlO2)12(SiO2)12·aq, have been investigated by measuring the fractional attainment of isotopic equilibrium between a ZnCl2 solution and a 65Zn-labelled Zn-A zeolite (30 and 45 µm particle radii) as a function of time, in the temperature range 25–60°C. The exchange mechanism is a two-step process which has been resolved, using the Brown–Sherry–Krambeck model, into diffusion in the solid particles, with Zn2+ diffusivity of D= 10–3.97 ± 0.03 exp (–ED/RT)m2 s–1, ED= 67.1 ± 0.5 kJ mol–1, and an intracrystalline first-order exchange between bound and mobile Zn2+ ions in the network, with a rate constant of k2= 103.05 ± 0.25 exp(–Ek/RT)s–1, Ek= 56.5 ± 1.5 kJ mol–1.