[Spectral analysis of dissolved organic matter derived from rice straw after chemical treatment]

Fourier transform infrared spectroscopy (FTIR), ultraviolet spectroscopy (UV), and nuclear magnetic resonance spectroscopy (NMR) were used to study the chemical composition of Dissolved Organic Matter (DOM) derived from rice straw in the hydrolysis process with a dilute complex acid solution. The results obtained are as follows. FTIR spectra could indicate the changes of DOM during the hydrolysis process of rice straw. With the progress of rice straw hydrolysis, methyl, methylene, aromatic compounds and carbohydrates decreased, most of aliphatic compounds were oxidized to CO2 and H2O, and others were turned into carbonates. Most of the organic silicon was hydrolyzed into inorganic silicon. The proteins, amino acids and other nitrogen were hydrolyzed to NH4+. All the recalcitrant fractions of rice straw, such as hemi-cellulose, cellulose and silicon sharply decreased during the process of chemical treatment. The results obtained in this paper proposed that the changes of DOM of rice straw in the hydrolysis could be an indication in the changes of chemical composition of rice straw during the hydrolyzation, and FTIR, UV and NMR were good methods to study the changes in the structure of organic compounds.