Contributions of A.N. Frumkin and the Frumkin School to power sources research

Journal of Solid State Electrochemistry - The historical interplay between the theoretical researches of the Frumkin School and the development of modern power sources technology is described. We...     

On the charge transfer in the process of adsorption at the electrode/solution interface: Remarks on the paper “experimental determination and interpretation of the electrosorption valency γ” by J. Schultze and K. Vetter

A critical analysis shows that the approach to the estimation of the charge transfer in the process of adsorption at the electrode/solution interface used by Vetter and Schultze in the general case is not justified without introduction of non-thermodynamic models. This approach can prove useful in the investigation of the electric double layer within the limits of applicability of Grahame's model. A number of cases can however be cited where the approach of Schultze and Vetter is inapplicable. The conclusions of Schultze and Vetter regarding the adsorption of hydrogen at platinum are apparently based on some misunderstanding. In this case the thermodynamic approach^{6, 23} should be used.It would be more correct to call the quantity γ “the formal coefficient of charge transfer”, rather than “the electrosorption valency”.     

Reduction of methylene blue by thiocyanate: kinetic and thermodynamic aspects

This article reports the reduction of methylene blue (MB) by thiocyanate ions (SCN(-)) in aqueous and micellar solutions. Thiocyanate ions are found to be an effective reducing agent for the decolorization of methylene blue under ambient condition. Effects of salting-in and salting-out agents have been investigated for real-time application in the reduction process. The salting-in agent urea has been found to uniquely enhance the rate of the reduction of MB by thiocyanate ion in the presence of micelles. Again, the catalytic activity of nanoparticles in the reduction of MB has also been studied. Detailed kinetic and thermodynamic aspects have been considered to realize the interaction between methylene blue and thiocyanate. Kinetic studies revealed that the reaction is reversible and follows first-order reaction kinetics.     

On the existence of several New O,N,F-Compounds. A Critical Comment on the paper by SICRE and SCHUMACHER

It is shown that the infrared spectra previously attributed to the three novel compounds FONO, NO₂F₃, and an unknown are due to the known compounds HONO₂, FONO₂, and covalent N₂O₅, respectively. The observed chemical and physical properties agree well with this reinterpretation.     

Discussion of problems of nonequilibrium thermodynamics of polymers as presented in the paper by Sommer and Reiter

A number of discussion points are raised concerning the nonequilibrium melting and crystallization as described in the paper by Sommer and Reiter.¹     

Continuous-flow delta18O measurements: new approach to standardization, high-temperature thermodynamic and sulfate analysis

The continuous-flow method for the determination of the O-isotope composition of solid samples has significant advantages over off-line extraction methods, but the problem has arisen of the standardization of results that has only partially been resolved by the use of water standards. We propose a new approach to standardization that uses carbothermic reduction of calcium carbonate standards catalyzed by high-purity AgCl. Analytical accuracy, precision, variance homogeneity and long-term stability are proven. Preliminary data on the barium sulfate delta18O analyses are reported, with a closer look at the different results obtained by off-line and on-line methods on intercomparison standards NBS-127 and MSS3.     

Equilibrium, kinetics and thermodynamic aspects of Promethazine hydrochloride sorption by iron rich smectite

Equilibrium, kinetics and thermodynamic aspects of sorption of Promethazine hydrochloride (PHCl) onto iron rich smectite (IRS) from aqueous solution were investigated. The effect of pH on sorption of PHCl onto IRS was also found out. Experimental data were evaluated by using Langmuir, Freundlich and Dubinin–Raduschkevich (DR) isotherm equations. Freundlich and DR equations provided better compatibility than Langmuir equation. Besides, it was determined that the maximum sorption of PHCl takes place at about pH 5. From kinetic studies, it was obtained that sorption kinetics follow pseudo-second-order kinetic model for PHCl sorption onto IRS. When thermodynamic studies are concerned, the values of activation energy (E_a), ΔG°, ΔH° and ΔS° were obtained. ΔG° values are in the range of −8.84 and −9.45 kJ mol⁻¹ indicating spontaneous nature of physisorption. The negative value of the ΔH° (−3.20 kJ mol⁻¹) indicates exothermic nature of adsorption. FTIR analysis and SEM observations of IRS and PHCl adsorbed IRS were also carried out. Sorption experiments indicate that IRS may be used effectively for the adsorption of PHCl.     

General problems associated with the analysis of amino acids by automated ion-exchange chromatography

Some of the general problems commonly encountered with the analysis of amino acids have been described. These include problems associated with the preparation and storage of samples prior to analysis and those associated with the analytical stage itself. The effects on the accuracy of the determination of amino acids have been discussed, together with possible solutions to some of the problems.     

An investigation on the structure,spectroscopy, and thermodynamic aspects of clusters: A combined Parallel tempering and DFT based study

The problem of identifying low-energy structures of (n = 1-6) was investigated, and the evaluation of important properties like heat capacity, solvation energy, and vertical detachment energy for each of the clusters was carried out. The problem was handled at two different theoretical levels. First, an adequately chosen empirical potential energy surface was used to account for the major interactions between the constituents of the cluster studied. Once the surface was chosen, the Parallel tempering algorithm was employed to search out the low-energy critical points on this surface, which gave geometries at this level. To refine the structures further, these pre-optimized structures were used as inputs for quantum chemical evaluation to complete the final refinement. To check whether the structures found were reasonable, sensitive properties like heat capacity, solvation energy, and vertical detachment energy were calculated. Then, an effort was made to understand and explain the variations in these properties with change in the cluster size. To understand the process of cluster formation further, thermodynamic aspects like △H (298.15 K), △G (298.15 K), and heat capacity (C_v) changes were also evaluated. Infrared spectroscopic features were also studied to see whether the introduction of the ion caused reasonable shifts compared to a pure water cluster.     

Efficient electrosorption of uranium(VI) by B,N, and P co-doped porous carbon materials containing phosphate functional groups

Journal of Solid State Electrochemistry - In this paper, polyphosphazene was synthesized as precursors using benzene-1,4-diboronic acid and hexachlorocyclotriphosphazene (HCCP) by a simple one-step...     

A thermodynamic interpretation of the behavior of higher fatty alcohols and acids upon the chromatographic paper

An idea was presented of treating the chromatographed substance as a “solute,” and the chromatographic system, composed of the stationary and the mobile phase as a “solvent.” Moreover the concept of “local equilibrium” was introduced, allowing to regard a given chromatographic spot as a “binary solution.” Thus a possibility arose to apply the classical thermodynamic approach, normally used for binary solutions, and namely: μ_i = μ_i + RT ln x_iƒ_i, where μ_i—chemical potential of the “i”-th compound in the solution, μ_i—chemical potential of the pure “i”-th compound, x_i-molar fraction of the “i”-th compound, ƒ_i—its activity coefficient, in a modified form, suitable for the chromatographic purpose.     

Efficient thorium removal by alginate-immobilized Aspergillus niger: characterization,kinetics, thermodynamic and mechanism analysis

Journal of Radioanalytical and Nuclear Chemistry - In this work, a modified biomass material was successfully prepared by immobilization and inactivation method based on Aspergillus niger, and the...