Factors determining the catalytic properties of active carbons in some acid-base and redox reactions

The results of the authors’ investigation of the catalytic properties of active carbons in acid-base and redox reactions are summarized. The general principles of controlling the activity of carbon catalysts are described, the main factors in the catalytic processes occurring on these catalysts are revealed, and new ways of using the catalytic properties of carbon sorbents from various sources are considered. The article was translated by the authors. Published in Russian in Kinetika i Kataliz, 2007, Vol. 48, No. 4, pp. 643–648.     

Development of procedures for preparing sorbents with improved structural characteristics from anthracite mining waste

Various procedures were suggested for activating anthracite mining waste (fine fraction) to obtain microporous sorbents with 60% (by weight) yield of the final product and pore structure characteristics (SBET = 400–600 m² g^?1, sorption pore volume 0.26 cm³ g^?1) close to those of commercial activated coals.     

Absorption of hydrogen sulfide on starting and modified carbons produced from technical-grade lignin

Processes in which hydrogen sulfide admixtures (from a 1% H₂S + 99% Ar mixture) are removed by sorption on starting carbons and those modified with alkali metal ins of various sizes, made from technical-grade lignin, and hydrogen sulfide is eliminated by catalytic oxidation of H₂S with oxygen were studied. The factors determining the absorption capacity of the carbons and their catalytic activity in oxidation of hydrogen sulfide were determined: these are, in the first place, presence of water in the pore space and in the hydration shell of modifying ions, size of these ions, and experimental temperature.     

Optimization of a method for the determination of a mustard gas biomarker in human blood plasma by liquid chromatography–high-resolution mass spectrometry

A method for the determination of a mustard gas biomarker (an S-hydroxyethylthioethyl adduct with albumin) in blood plasma was optimized with the use of HPLC with high-resolution tandem mass-spectrometric detection. This method is based on the hydrolysis of this adduct by the proteinase K enzyme with the formation of the following stable tripeptide with cysteine, proline, and phenylalanine: S-[HETE]-Cys- Pro-Phe. The conditions of the sample preparation of human plasma artificially contaminated by mustard gas (the selection of an aliquot portion volume and an enzyme for the hydrolysis), the mass-spectrometric detection (the selection of optimum pairs of ion reactions and high-resolution detection modes), and the gradient elution program in the HPLC separation of an analyzed mixture were optimized. The detection limit of mustard gas in human blood plasma was 1 ng/mL. The approach proposed was tested in the analysis of human blood plasma samples by the standard addition technique and also within the framework of the first official biomedical test carried out by the Organization for the Prohibition of Chemical Weapons (OPCW) in 2016, and it exhibited a good accuracy, reproducibility, and specificity of determination.     

Total internal reflection imaging of microorganism adhesion using an oil immersion objective

In this paper, we report the results of total internal reflection microscopy investigations of the interaction of two types of microorganisms: Saccharomyces cerevisiae and Escherichia coli with substrates. It is shown that with this method qualitative and quantitative information about cells-substrate interaction can be obtained. One can easily make a difference between attached and non-attached as well as between dead and alive cells, and more generally can follow the dynamics of the process of cells' attachment to substrates. Quantitative information about the cell size and cell-substrate distance is obtained by using a model in which yeast cells and bacteria are approximated by ellipsoids, and multiple reflections of the evanescent waves between the cells and the substrate are neglected.     

Conversion of Respirator Charge into Carbon Sorbents

A simple and efficient liquid-phase procedure was developed for the oxidative-degradation regeneration of the spent respirator charge yielding oxidized carbon with fairly high sorption capacity to heavy metal ions with a minimal loss in the strength and in the amount of the carbon material.     

Effects of the reaction medium on the chemical nature of the surface of carbon catalysts during esterification, ester hydrolysis, and hydrogen peroxide decomposition

The state of the surfaces of hydrogenated and some cation-substituted forms of oxidized carbons before and after liquid and gas phase catalysis of esterification, ester hydrolysis, and decomposition of aqueous hydrogen peroxide have been studied by IR spectroscopy and chemical analysis. It was found that surface reactions between functional groups and the absorbed reagents (esterification) or products (hydrolysis) or the formation of new functional groups by redox decomposition of H₂O₂ can occur alongside normal processes on the carbons. It has been shown that the biggest change in the chemical nature of the surface (along with the initial reduction of catalytic activity up to the establishment of the stationary state) occurs with the hydrogenated form of the oxidized carbons in comparisons with the cation-substituted carbons. It was observed that when ionic forms of oxidized carbons were used there was practically no change in the chemical nature of the surface, and that the catalytic activity was greater which makes them promising catalysts for the processes studied. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 34, No. 1, pp. 47–52, January–February, 1998.     

New Carbon Aerogels Fabricated from Polymeric Materials and Their Properties

Electron microscopy and adsorption-structural, X-ray phase, and thermal analyses were used to determine the density, porosity, microstructure, electrical conductivity, and reactivity of new carbon aerogels based on phenol-formaldehyde polymers.     

Development of Procedures for Synthesis of Carbon Materials with Molecular-Sieve Properties

New methods for synthesis of uniformly porous carbon materials with sieve properties and small apparent density from phenol-formaldehyde resins were developed; the optimal conditions of their synthesis were determined. New types of finely dispersed carbon powders were prepared using various treatment procedures at different stages; the structural and sorption properties of the resulting materials were studied.