CHARACTERISTICS OF PYROGALLOL-DERIVED POLYMERS FORMED BY CATALYSIS OF OXIDES

The influence of the nature and properties of oxides in soil and sediment environments on the characteristics of polyphenol-derived humic polymers formed by abiotic catalysis is not fully understood. The objective of this study was to investigate the catalytic power of Mn(IV), Fe(III), Al, and Si oxides in the transformation of pyrogallol and the development of carboxylic and aliphatic groups in the resulting humic polymers. The metal oxides differed significantly in their effectiveness for catalyzing pyrogallol humification. The results indicate that the carboxylic group of humic polymers developed as a result of ring cleavage of pyrogallol catalyzed by the oxides. The ability of short-range ordered oxides of Al, Si, and especially Fe and Mn, in enhancing the formation of aliphatic and carboxylic groups in humic polymers derived from polyphenol humification may, in part, contribute to the origin of aliphaticity of humic substances and the variation of their characteristics, including carboxylic group contents with soils from different climatic zones.