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To study the effect of various extractants on the structure of peat humic acid, peat humic acid was extracted using [NH.sub.3]*[H.sub.2]O, [Na.sub.2][CO.sub.3], [NaHCO.sub.3], and [Na.sub.2][SO.sub.3] via alkali-extraction and acid-precipitation methods. The extracted peat humic acid was characterized using ultraviolet-visible (UV-vis) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, and fluorescence (FL) spectroscopy. The results showed that the extractants had negligible effects on the content of peat humic acids. [Na.sub.2][CO.sub.3] was found to be the most effective extractant for isolating humic acids from peat, with the highest content of 66.20% and a yield of 32.67%. Moreover, among the extractants used, [NH.sub.3]*[H.sub.2]O resulted in humic acids with the highest aromaticity, and [Na.sub.2][SO.sub.3] yielded humic acids with higher number of hydroxyl groups. [NaHCO.sub.3] yielded humic acids with the most aliphatic ether and lowest aromaticity. [Na.sub.2][CO.sub.3] was the best extractant for isolating humic acids from peat, having the highest content, lowest degree of aromatic polymerization, and highest number of carboxylic acids., Plant organisms gradually form peat through the slow de com position of anaerobic microorganisms under excessive water and insufficient air environments (1). Peat originates from mosses and woody and herbaceous [...]

The conversion of lignite into biomethane is of great significance in the field of energy research. However, the yield of biomethane is low. To improve the biomethane yield from lignite, the effects of ultrafine grinding lignite on the biomethanation fermentation system were analyzed. The daily biomethane yield, total biomethane yield, pH, glucose concentration, and volatile fatty acid concentration of lignite were used to determine the optimum particle size of lignite. The results demonstrated that the total biomethane yield of the fermentation group with ultrafine grinding lignite was 14.69 mL·g−1 at a reaction temperature of 50°C and a biomethane fermentation time of 39 d. This was 36.91, 33.42, and 26.75% higher than that of the 40, 150, and 250 mesh lignite biomethane fermentation groups, respectively. The daily biomethane yield reached the peak of the ultrafine grinding lignite fermentation group 1.30 mL·g−1 on the second day, which was 1.96, 1.63, and 1.04 times higher than that of the 40, 150, and 250 mesh lignite fermentation systems, respectively. The research demonstrated that ultrafine grinding of lignite can effectively increase the biomethane yield. This provides an effective method for improving the yield of biomethane from lignite. [ABSTRACT FROM AUTHOR]

Peat is an organic mineral resource. Peat contains a large amount of humic acid, and extracting humic acid from peat is a way to efficiently utilize peat. This article mainly studies the effects of using woody, herbaceous, and mossy peat as raw materials on the yield, content, and especially molecular structure of humic acid extraction, including that the oxygen-containing functional groups of humic acids, aromatic carbon content, microcrystalline structure, carbon chain structure, and degree of aromatization. The results showed that the highest yield of humic acid in woody peat was 54.33%, the yield of humic acid in herbaceous peat and mossy peat are relatively low, at 44.67% and 15.00%, respectively. while the woody peat humic acid has the lowest content, that is 38.38%. The content of humic acid in herbaceous peat was 77.33%. and the content of humic acid in mossy peat is 57.85%. Through comprehensive consider, herbaceous peat is more suitable for extracting humic acid. At the same time, this article studies the molecular structures of three peat humic acids and concludes as follows. Woody peat humic acid has the highest degree of aromatization, the highest content of benzene ring, and more functional groups such as methyl, phenol, aromatic ether, carbonyl, and hydroxyl groups. The content of methoxy and methylene groups in herbaceous peat humic acid is relatively high. Through XPS characterization analysis, it was found that the main forms of oxygen element in humic acid are C = O, C-O, and -COOH, without inorganic oxygen. The humic acid extracted from different types of peat has significant differences in yield, purity, and functional group content. Compared to woody peat and mossy peat, herbaceous peat is the most suitable raw material for extracting humic acid from peat. [ABSTRACT FROM AUTHOR]