Modification of Natural Shungites To Obtain a Mixed Nanocarbon Material (MNS)

Abstract

An original technology for processing of a natural material, shungite-3 from the Zazhogino deposit (Karelia), was developed in order to obtain a new product, mixed nanocarbon material (MNS).It is suggested to obtain a nanocarbon material (MNS) by using the available natural raw material, shungite rock widely occurring in the geologic profile of the world's largest Onega basin (Republic of Karelia) of Precambrian black-shale sedimentation. To the shungite rock is commonly related a large group of compositionally different carbon-containing Precambrian geologic formations. Commonly, rocks with 5310% shungite substance are named shungitious, and those with 0.535%, shungite-containing. To highcarbon shungite rocks belong those in which the content of free shungite carbon exceeds 20%.The total estimated resources of the shungite rock of the Onega basin according to Mikhailov [1] exceed one billion tons (1041 million), and the prospected resources (of classes B + C1 + C2) of the largest Zazhogino deposit (in Medvezh'egorskii district) are 148.8 million tons (reserves 321.8 million tons), with the average content of the shungite carbon, e.g., in the Maksovskaya bed, is about 31%.Shungite (shungite rock) of the Zazhogino deposit is, on the average, composed of 30% carbon and 70% silicates [2]. It is by the content of carbon that it is referred [2] to the third variety of shungite rocks (shungite-3), or, according to the geological-genetic classification by Filippov, to maxovites, which are saprobitumolite rocks having the form of a fine homogeneous mixture of a shungite substance and a cryptocrystalline mineral substance. The conditions of the regional metamorphism of shungite rocks correspond to the chlorite and biotite zones of the greenshale facies. The microelements found in these rocks are Fe, Ti, V, Ni, Cu, and Zn, mainly in the sulfide (pyrite, pyrrhotine, sphalerite, etc.) and oxide (rutile etc.) mineral forms.The conditions in which shungites are formed, as well as their chemical and phase composition, suggest that fullerenes and(or) fulleroid components of carbon fractions are present in natural shungites. Here and hereinafter by fullerenes are meant light fullerenes C 60 and C 70 and heavy fullerenes C 76 , C 78 , C 84 , and C 90 , as well as their mixtures; and by fulleroid materials are understood single-and multi-walled nabnotubes, nanobarrels, nano-onions, nanocones, and mixtures of these [4,5].The authors developed an original technique for mechanical and chemical processing of shungite-3 to obtain a heterogeneous catalyst. The technique includes the following processing stages: (a) decomposition of the rock in an alkaline (NaOH) melt at a temperature of 500 3520oC to remove aluminosilicate and silicate components; (b) washing of carbon phases with water to remove trace amounts of the alkali, with the subsequent grinding and sieving to obtain a powder with a grain size of 803100 mm; (c) acid treatment of carbon phases (HNO 3 65 wt %) at 60 3 65oC for 335 h to remove mixtures of metals, their oxides, and s...

Graphene platelets from shungite rock modulate electropolymerization and charge storage mechanisms of soft-template synthetized polypyrrole-based nanocomposites

“…The settling of efficient purification procedures able to eliminate the silicates and other species present in the pristine SH rock and to obtain a network of pure carbon phase, is undoubtedly a fundamental step preliminary to any other experimental activity. Based on literature considerations about the use of HF or NaOH to eliminate silicates 46 , of HNO 3 or HCl to remove metals, oxides and amorphous carbon 47 , new purification procedures were settled by combining some of the proposed reactants. The treatments performed on the pristine SH powder are the following:…”

Shungite Carbon as Unexpected Natural Source of Few-Layer Graphene Platelets in a Low Oxidation State

“…A systematic study allowed us to define a protocol for SH processing able to eliminate foreign species and amorphous carbon, limiting at the same time the oxidation degree of the final material. This goal was achieved by adopting the below described procedure, that was settled taking into consideration previously reported strategies to eliminate silicates, to remove metals, oxides, and amorphous carbon …”

“…A systematic study allowed us to define a protocol for SH processing able to eliminate foreign species and amorphous carbon, limiting at the same time the oxidation degree of the final material. This goal was achieved by adopting the below described procedure, that was settled taking into consideration previously reported strategies to eliminate silicates, 45 to remove metals, oxides, and amorphous carbon. 46 The as-received SH powder, that henceforth will be named as sample S, was dissolved and kept under power ultrasound for 12 h in an aqueous solution of 20 M HF and 15 M HNO 3 in a 1:1 volume ratio.…”

SEM investigation of minor constituents of carbide materials prepared from shungite rocks

“…Over the last decade, shungite have actively been studied by many researchers (e.g. Kalinin et al 1999;Grigor'eva and Rozhkova 2000;Kovalevski et al 2001;Rozhkova 2002;Parthasarathy and Vairamani 2003;Cascarini de Torre et al 2004;Charykov et al 2005;Yefremova 2005;Kwiecinska et al 2007;Polonskii et al 2007;Strakhov 2008), who examined its physicochemical characteristics as well as ability and reasonable means to use the same for various purposes. So it was revealed that the shungite rocks are natural "agglomerated" charging materials in which carbon forms a strong matrix permeated by a finely dispersed silicate skeleton with a highly developed contact surface.…”