Spectral characteristics of dissolved organic matter in the process of coal gasification by microorganism

In order to further explore the changes of organic intermediates during coal biogas production, three different coal samples were applied for the simulated biogas experiments using the domesticated river sediments as the bacteria source.The biogas yield, the dissolved organic matter content (TOC), UV spectrum and three-dimensional fluorescence spectrum of the liquid samples were measured, and the potential coupling relationship between the biogas yield and the spectrum changes were studied.The gas production process could be divided into three periods:a fast one, a slow one and an inhibition one.TOC declined throughout the process, with a slight increase in the third period, and the change of TOC had the same trend as gas production period.The changes of UV spectrum showed that the molecular weight and the aromatization degree of the dissolved organic matter increased.And at the same time, the functional groups containing oxygen on the aromatic ring increased.The gas production was fast when aromaticity increased, while slow when aromaticity decreased.Fluorescence spectra showed that the fluorescence peaks of the class-like proteins were rapidly decreased in the process, the humic acids in coal were transferred to the liquid phase.And the carbonyl, amine, and hydroxyl groups in the fluorophore were increased.The results above indicated that the organic matters were released into the liquid phase to take part in the biogas generation.The conclusions are consistent with the results of the study using GC-MS.This research has applied a new idea and method for the studying on the biogas generation from coal.