A comprehensive analysis of various structural parameters of Indian coals with the aid of advanced analytical tools

Abstract

An exhaustive structural analysis was carried out on three Indian coals (ranging from sub-bituminous to high volatile bituminous coal) using a range of advanced characterization tools. Detailed investigations were carried out using UV-Visible spectroscopy, X-ray diffraction, scanning electron microscopy coupled energy dispersive spectroscopy, Raman spectroscopy and Fourier transform infrared spectroscopy. The X-ray and Raman peaks were deconvoluted and analyzed in details. Coal crystallites possess turbostratic structure, whose crystallite diameter and height increase with rank. The H/C ratio plotted against aromaticity exhibited a decreasing trend, confirming the graphitization of coal upon leaching. It is also found that, with the increase of coal rank, the dependency of I 20 /I 26 on L a is saturated, due to the increase in average size of sp 2 nanoclusters. In Raman spectra, the observed G peak (1585 cm -1 ) and the D2 band arises from graphitic lattices. In IR spectrum, two distinct peaks at 2850 and 2920 cm -1 are attributed to the symmetric and asymmetric -CH 2 stretching vibrations. The intense peak at *1620 cm -1 , is either attributed to the aromatic ring stretching of C=C nucleus.

Tunable direct band gap photoluminescent organic semiconducting nanoparticles from lignite

“…The nitrogen groups are probably originated from lignite or during HNO 3 oxidation, which acts as a doping agent of nitrogen into organic dots. The band at 2922 cm −1 arises from the asymmetric vibration of sp 3 bond in CH 2 and CH 3 groups in the hydrocarbon network 13 , 14 . The peak at 2851 cm −1 is ascribed to the overlapping of symmetric vibration of a sp 3 band of CH 3 and CH 2 functional groups.…”

Extraction and Characterization of Preformed Mixed Phase Graphene Sheets from Graphitized Sub-Bituminous Coal

“…The large number of defects and disorder can lead to defect activated bands such as D band and an overtone of D-2D band. These bands may lead to a broad peak due to merging and result as a bump like shape for the 2D band [19,20]. The 2D band is fitted with multiple Lorentian profile has 6 peaks, the 3 intense peaks are G*, G', D+D' bands at 2431, 2630 and 2859 cm -1 and other peaks are cosidered to be residual peaks (Fig.…”

Synthesis of Graphene Oxide Nano Structures from Kerosene Soot and its Impedance Analysis

“…This N-H stretching in 3500-3400 cm -1 region is a sign of primary amines. There is also, a signal at 802 cm -1 which points to C=C alkene bending [5][6][7][8][9].…”

“…At 2354 cm -1 , there is another trough, which is attributed to carbon dioxide stretching. At 3386 cm -1 the trough corresponds to N-H stretching and the nature of the functional group is an aliphatic primary amine [7][8][9][10][11][12].…”