Abstract

CONTRERAS, Eliasara; LEAL, Edgardo  and  MARTINEZ, Manuel. Effect of temperature, oxidation time and substrate: oxidant agent ratio in the yield and composition of humic acids derived from coal, monitored by ¹H NMR and FT-irEfecto de la temperatura, el tiempo de oxidación y la relación oxidante/sustrato en el rendimiento y composición de los ácidos húmicos derivados de carbón, seguido por RMN de ¹H y FT-ir. Rev. Téc. Ing. Univ. Zulia [online]. 2004, vol.27, n.2, pp.114-122. ISSN 0254-0770.

The yield and composition of coal-derived humic acids (AH) was studied, obtained by oxidation of a Venezuelan bituminous coal with alkaline potassium permanganate under different temperature, reaction time and substrate: oxidizing agent ratios, with the aim of establishing the optimal conditions of extraction and yield, and to compare the structure of the generated AH. Oxidation products were analyzed by ¹H RMN, FT-ir and elemental analysis. The yield of AH obtained by coal oxidation is increased as temperature and time increasing, and it decreased with the increase of the relationship KMnO₄ to coal. Elemental composition of the obtained AH differs not very to each other, except for those coming from the reactions in that the oxidizing ratio to coal is 3:1. The yields, as well as the spectroscopic and compositional results clear evidence that the AH initially formed in the oxidation of the coal, are further oxidized by the excess of oxidizing agent, to generate structures simpler and fulvic acids.

Keywords : Humic acids; coal; weathering; oxidation; NMR; FT-ir.