University of Guilan Caspian Journal of Environmental Sciences 1735-3033 21 5 2023 12 01 Thermogravimetric analysis of brown coals and also humic acids as well as their extracted bitumens in the Circumpolar Urals 1309 1313 7336 10.22124/cjes.2023.7336 EN Olga Alexandrovna Gurova Department of Biological Sciences, Yugorsk State University, Higher Oil School, 16 Chekhov St., Khanty Mikhail Petrovich Sartakov Department of Biological Sciences, Yugorsk State University, Higher Oil School, 16 Chekhov St., Khanty Journal Article 2023 12 10 The purpose of this work is to study the thermal stability of humic acids and bitumens extracted from brown coals of the Circumpolar Urals in the Khanty-Mansi Autonomous Okrug-Ugra. Waxes, bitumens and resins were extracted from brown coals with benzene on Soxhlet apparatuses. Extraction of humic acids was carried out by the Instorf method. Thermal analysis of all humic acid samples was performed at Novosibirsk Institute of Organic Chemistry in the Siberian Branch of the Russian Academy of Sciences on a STA 409 PC Luxx synchronous thermal analyser (Netzsch Company) in an inert atmosphere in a platinum crucible. It was found that thermal stability of humic acid macromolecules obtained from brown coals is characterized by typical thermal effects and quantitatively different value of macromolecule destruction within the ranges from 220 to 400 °C and from 400 to 800 °C. https://cjes.guilan.ac.ir/article_7336_357c8f5d9ac7769fe2f2a142e3e1d241.pdf