Spectroscopic, thermic and metal binding properties of commercial humic acid and leonardite

Abstract

Humic acids are formed from a combination of variable chemical groups found in natural sources containing partially aromatic groups in an amorphous structure. These substances have been shown to significantly impact plant biomass, affecting nutrient distribution through direct interaction with the plant and nutrient supply and regulation through indirect interaction. The lack of a regular and repeating molecular structure in humic substances makes them challenging to determine. Humic substances used in agriculture commercially are humic and fulvic acid or combinations of both in different proportions. In our research, we used spectroscopic and thermal methods to understand the structures of commercial samples. We conducted FT-IR (Fourier Transform Infra-Red) spectroscopy to analyze the structure's bonds, thermal analysis to comprehend its thermal properties, and NMR (Nuclear Magnetic Resonance) analysis to obtain information about the carbon content. By combining, comparing, and interpreting all these methods, we can predict commercial samples' spectroscopic and thermal properties during the production stage. This can serve as a foundation for researchers studying or utilizing humic acid.