Photochemical Degradation of Organic Pollutants in Solutions of Soil Humic Acids

Abstract

Chernozem humic acid (HA) fractions with nominal molecular sizes (MS) >100, 30–100, 5–30 and <5 kDa were obtained, using a combination of low-pressure preparative size exclusion chromatography with analytical polyacrylamide gel electrophoresis or multistep ultrafiltration. The initial HA and fractions were tested for the ability to destroy model aromatic compounds 2,4,6-trimethylphenol and furfurol in aqueous solution when illuminated with polychromatic light in the range 300–450 nm under laboratory conditions. It has been found that chernozem HA fractions with MS less than 5 kDa had the maximum ability to decompose the above-mentioned substances, while fractions with MS above 30 kDa practically did not perform this function. The data obtained allow us to explain partially the mechanisms of the photoinduced transformation of many organic pollutants by soil humic substances.