DIFFERENTIAL THERMAL ANALYSIS AND INFRARED INVESTIGATIONS ON SOIL HYDROPHOBIC SUBSTANCES

Abstract

The differential thermal analysis [DTA] of a water-repellent soil, collected in a coastal pine forest, was characterized by 2 exothermic peaks in the temperature range of 220 550.degree. C. The 2nd exothermic peak was suppressed, as well as the nonwettable property, after extraction of the soil with benzene. Further differential thermal analyses on the extracted material substantiated a positive correlation between them. The DTA coupled with the IR spectrophotometry suggested the hypothesis that the soil''s water-repellency may be due to a fraction of organic matter with a low degree of humification. The IR investigation and fractionation by absorption chromatography of the extracted substances showed their great complexity; the only hypothesizable compound arrangement was an ester between phenolic acids and polysaccharide-like substances. The complete combustion curve of the soil''s water-repellent substances suggested that only temperatures above 550.degree. C can destroy the nonwettable property in the soil.