L.E. Gorlenko

From stable aqueous dispersion of carbon nanoparticles to the clusters of metastable Shungite carbon

Aqueous dispersion of Shungite carbon (ShC) condensation is followed by aggregation of carbon nanoparticles and further net formation. Data obtained by adsorption methods that characterized changes in porosity of natural shungites when transformed into aqueous dispersion and precipitated, were investigated. Pore size distribution determined for natural shungites is characterized by micro- and submesopores of <0.7–5.0 nm in size predominantly. It correlates with values of basic structural elements (0.4–0.7 nm) releasing into aqueous dispersion and with the primary ShC globular aggregates less than 6.0 nm in size. Decreasing of specific surface and total pore volume while the mean pore radii remains constant, were observed when oxidizing (ozonating) and heating of carbonaceous net. Different stages of ShC nanoparticles aggregation in nature were modeled in laboratory under concentration of stable aqueous dispersion.

Low-Temperature Oxidative Modification of Lignites and Lignite-based Cokes

The kinetics of oxidation of lignites and cokes with ozone in the gas and liquid phases and the composition of oxidation products were studied. The surface area and porosity were measured before and after ozonization. Ozonization increased the surface area largely because of the growth of micro-and mesopores. Changes in the composition of functional groups on the surface of lignites and cokes were determined IR spectroscopically. Adsorbents with the required properties can be prepared by varying the concentration of ozone and ozonization duration.

Effect of the conditions of structure formation on the physicochemical properties of ozonated shungites

It was investigated the influence of ozone on the physicochemical properties of shungites (type 1) (75–98% C) from Nigozero and Chebolaksha deposits (Karelia) formed by hydrothermal (Nigozero) and high-temperature (Chebolaksha) processes. Ozonation was found to affect the specific surface and the total pore volume of shungites considerably. The pore size distribution pattern depends on the volume morphology (texture) of the sample. An increase in the temperature and pressure during the structure formation of shungite (Chebolaksha) led to a shift of the maximum on the distribution pattern towards the formation of mesopores. The size distribution of pores with the dominant contents of micro- and submesopores for both shungites correlated with the basic structural nanoelements of shungite carbon. The peculiarities of the ozonation of shungite nanocarbon found previously (the non-steady state vibrational kinetics of ozonation and the absence of carbon(II) oxide among the reaction products) were confirmed.

Catalytic Activity of Nanodiamonds in Redox Process

Properties and chemical composition of detonation nanodiamonds (ND) vary with production conditions and degree of purification. The presence of catalytically active metals in ND suggests that they could be regarded as ready-made nanostructured metallic catalysts on carbon carriers. Catalytic activity in ozone decomposition as a model reaction of redox processes was studied on ND offered by various authors. The specific surface and volume of pores are observed to change slightly during ozonation, whereas the average radius of micropores remains constant and does not depend on the method of synthesis and the ND purification details. However, they are shown to exert a substantial effect on the ND microstructure and chemical composition and, consequently, catalytic activity and adsorptive properties.