The thermal stability of humic substances (humic acids, sodium humate and ammonium humate) manufactured on the plant or pilot plant scale was examined within the temperature range 150-250°C with a period of heating up to 60 min. Under these conditions no significant destruction of the skeleton of the humic substances occurs; in spite of a certain loss in weight, these materials retain the fundamental characteristics of humic substances such as the content of functional groups and the distribution of molecular weights. By heating ammonium humate to 150°C, liberation of ammonia takes place and the resulting product has the properties of pure humic acids. © 1995.
Janoš, P., & Kozler, J. (1995). Thermal stability of humic acids and some of their derivatives. Fuel, 74(5), 708–713. https://doi.org/10.1016/0016-2361(94)00007-E