ИСТИНА

Conversion of lignin-containing organic matter into qualitative organic fertilizers is an important task of the present. LTD RET Company has developed and patented an industrial technology for the conversion of technical lignosulfonate with following synthesis of a number of humic-like biologically active substances (HLS), which finally compose the commercial humic product Lignohumate® (LH). Depending on the technological regimes used (alkali content, changes in temperature, pressure, oxidation rate and time), composition and properties of the obtained product are different. The objectives of the study were: (1) to characterize chemical composition and biological activity of the product in a number of LH samples taken at different times during the technological process; (2) to reveal differences in LH composition as a function of time and to determine the optimum duration of the process for obtaining a high-quality product. Samples of LH were taken from the heated working mixture at 0, 15, 30, 45, 60 and 120 min from the start of the oxidation process. Chemical parameters (elemental content, functional groups, carbohydrate content, MW, FTIR, 13C-NMR) were determined, biological activity was evaluated in phytotests as an increment of oven-dry biomass of shoots and roots of radish. Principal component analysis (PCA) was carried out considering set of chemical data and root biomass. Data on chemical parameters and biological activity combined with PCA show that LH-samples can be divided into three groups, depending on the duration of synthesis: initial raw material (0-time sample); “young” HLS (15-30 min) and “mature” HLS at 45-120 min of treatment. Starting from 15 min, content of HLS, elemental composition, content of functional groups, molecular weight distribution, character of IR and 13C-NMR spectra change. After 45-60 minutes the composition stabilizes, the share of high molecular weight fraction increases, and biological activity reaches maximum. At that stage further synthesis can be stopped.