Spectroscopic Analysis of the Effects of Alkaline Extractants on Humic Acids Isolated from Herbaceous Peat

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 [...]