Influence of gamma-radiation on the behavior of humic acids from peat and tropical soil

HA samples obtained from sedimentary soil and peat in aqueous media were irradiated with gamma-rays, in the dose range from 10 to 100 kGy, with the aim to study the chemical differences in the material before and after irradiation. ?he materials were analyzed by elemental analysis, UV/Vis spectroscopy (E4E6 ratio), functional groups content, gel permeation chromatography (GPC) and IR spectroscopy. Gas chromatography was utilized to analyze the generated gases. Humic acids from peat and from soil are quite different After irradiation an increasing in the average molecular weight was observed which depends on the material characteristics. There was observed also a release of CO2 upon irradiation. By infrared spectroscopy, with the help of computer simulations, the characteristic bands of ester C=O and C-O stretchings reinforces the contribution of carboxylic groups in the condensation process.