Browsing by Author "Amrendra Kumar"

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Investigations of coal beneficiation by using choline chloride and urea-based deep eutectic solvent
(Taylor and Francis Ltd., 2023) Ankur Dwivedi; Arpita Dwivedi; Amrendra Kumar
The present study reports on the interaction, influence, and dissolution properties of coal samples (CS) by a green solvent, deep eutectic solvent (DES), prepared from choline chloride and urea. The bituminous coal has been collected from the Singrauli coalfield in India. DES was synthesized using urea as a hydrogen bond acceptor (HA) and choline chloride as a hydrogen bond donor (HD) in an equimolar amount. The synthesized DES has been used in the study for swelling behavior, proximate and ultimate analysis, and FTIR to understand the beneficiation of coal after DES treatment. The swelling index of DES-treated coal ranges from 1.12 to 1.43 when compared to raw CS. FTIR confirms the presence of different oxygen-containing phenolic, aromatic, and aliphatic hydrocarbon containing functional groups present in coal samples. Quantitative analysis of FTIR peaks was carried out through the Gaussian function peak processing method. Fourier transform infrared (FTIR) analysis of the raw coal and treated sample confirms the reduction of oxygen-carrying and phenolic vibrational groups by up to 86%. The ultimate and proximate analysis of raw coal and DES-treated CS shows the decrease in ash content (up to 26%) of DES-treated coal samples and confirms the FTIR results. Calorific value in the form of fixed carbon content was also increased by up to 4.7% after DES treatment. Hence, DES treatment efficiently benefits coal properties and makes them more useful for the industrial environment. © 2022 Taylor & Francis Group, LLC.
Qualitative surface characterization of Indian Permian coal using XPS and FTIR
(Taylor and Francis Ltd., 2023) Ankur Dwivedi; Arpita Dwivedi; Amrendra Kumar
This paper reports on the surface properties associated with high-ash Indian Permian coal, which primarily depend on its geochemical compositions. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) techniques have been used to assess surface properties. The results confirm the presence of different elements, mineral phases, and organic functional groups in coal. The XPS survey confirms the presence of different elements on the surface of the coal. Some of them are C 1s (286.0 eV), O 1s (534.5 eV), N 1s (399.9 eV), S 2p (158.2 eV), such as SiO2 and Al2O3, which correspond to Si 2p (102.7 eV) and Al 2p (75.6 eV) with other clay minerals. XPS spectra of C 1s confirm the presence of aliphatic and aromatic carbon, which are hydrophobic compared to hydrophilic groups such as alcoholic, carboxylic, and phenolic. FTIR also validates the existence of hydrophobic functional groups as being higher than hydrophilic groups. Proximate and ultimate analysis results also confirm the presence of less moisture and a higher carbon percentage in the coal samples. Hence, the inherent hydrophobicity of the coal surface is excellent, and the surface hydrophobicity of coal can also be characterized using XPS and FTIR techniques. This information about the coal properties will be very beneficial for coal beneficiation and utilization. © 2022 Taylor & Francis Group, LLC.