Spectral signatures of solvent-extracted macromolecules in Indian coals of different rank: Insights from fluorescence excitation-emission matrix  

作　　者：Archchi Sarkar Uttam Kumar Bhui Krittibas Das Sudip Bhattacharyya Jitendra Kumar Darshan Halari 

机构地区：[1]Department of Petroleum Engineering,School of Energy Technology,Pandit Deendayal Energy University,Raisan,Gandhinagar,Gujarat 382007,India [2]Specialized Coal Petrography Laboratory,Natural Energy Resources Division,Mission II-B,Geological Survey of India,DK-6,Sector-I,Salt Lake City,Kolkata,West Bengal 700085,India

出　　处：《International Journal of Coal Science & Technology》2024年第5期107-120,共14页国际煤炭科学技术学报(英文)

摘　　要：Solvent-extracted fractions of six Indian coal samples of different ranks were investigated using multiple geochemical,petrological and spectroscopic proxies and an attempt was made to indicate possible fingerprint regions for different polycyclic aromatic hydrocarbons(PAH)with the help of excitation-emission matrix(EEM).In this study,for the very first time,the influence of rank and maturation of organic matter in the characterisation of coal solvent-extracts from Indian coals were perceived from the viewpoint of fluorescence EEM.Vitrinite reflectance(VR_(0))values were used to determine the general ranks of the original coal samples viz.lignite,subbituminous,bituminous and anthracite.Different fluorescence peak regions corresponding to different fused aromatic ring(FAR)systems were delineated using the EEM and their indicative depositional environments could be inferred.Our observations indicate that solvent-extracted fractions of low rank coals comprise of a larger number of shorter carbon chains compared to the other samples.For the low rank coal samples,the solvent-extracts show a strong humic influence and the presence of smaller PAH rings while for the medium rank coals,the extracted fractions tend to show a more bimodal distribution of PAHs,possibly comprising of different sized PAHs.Higher fluorescence sensitivity and quick response of smaller PAHs impart a singular centralised region in the EEM for the low rank coal samples while interference in the fluorescence of differently sized PAHs indicate a multimodal distribution of the fluorophores in the medium rank coals.The high rank coal used in this study shows a bimodal distribution with very low intensity of the peaks,indicating the low abundance of extractable macromolecules,possibly as a result of deformation.

关 键 词：Solvent extraction Indian coal Fluorescence spectroscopy UV-visible absorption spectroscopy Excitationemission matrix 

分 类 号：P61[天文地球—矿床学]