Investigation on Humic Acids of the Shivee-Ovoo and Ulaan-Ovoo Coal in Mongolia

Humic acids are highly oxidized organic compounds originated from plants and coals. Therefore, the coals of the Shivee-Ovoo and Ulaan-Ovoo deposits were analyzed by proximate, ultimate, and FTIR spectroscopic analysis. It was confirmed that the Shivee-Ovoo coal is a low-rank lignite coal of B2 mark, and the Ulaan-Ovoo coal is subbituminous coal. So, they are suitable raw materials for obtaining humic acids. The yield of humic acids from the Shivee-Ovoo coal is 23.2 % and their solubility in water is 78.05 %. The yield of humic acids of the Ulaan-Ovoo coal is 14.5 % and the solubility in water is 23.20 %. The yield of humic acids and the water solubility of the Shivee-Ovoo coal are much higher than those of the Ulaan-Ovoo coal, because the coal of Shivee-Ovoo deposit is a highly oxidized brown coal, while the coal of the Ulaan-Ovoo deposit is a higher rank subbituminous coal. These results show that the humic acids of both kinds of coal have good penetration ability in soil and higher bioavailability for plants. The IR spectra of humic acids of both coals and their humic acids show that the organic matter of humic acids consists mainly of aliphatic and aromatic compounds with carboxylic (-COOH), carbonyl (>CO), hydroxyl (-OH) and etheric (-O-) groups, which are characteristic of highly oxidized organic matter. Humic acids of the Shivee-Ovoo coal exhibit a high biological activity in relation to Iren wheat seeds. The highest biological activity was detected for humic acid concentration of 0.005 %.

Automated summary

The study found that coals from Shivee-Ovoo and Ulaan-Ovoo deposits are suitable raw materials for obtaining humic acids. Humic acids extracted from Shivee-Ovoo coal have much higher yield and water solubility compared to those from Ulaan-Ovoo coal, attributed to the former's highly oxidized nature. Additionally, the organic compounds in humic acids from both coals consist mainly of aliphatic and aromatic compounds, with carboxylic (-COOH), carbonyl (>CO), hydroxyl (-OH) and etheric (-O-) groups, characteristic of highly oxidized organic matter.