Studies on the Chemical Structure of Regenerated Humic Acid (I)

Abstract

Since it is very difficult to investigate the chemical structure of coal itself by chemical means, studies of the regenerated humic acid which is the primary decomposition product of coal have been done.In this paper, the results of experiments carried out for preparing the regenerated humic acids from some kinds of coal by alkaline fusion method were reported. Sodium or potassium hydroxide was used as a reagent of the alkaline fusion, and the reaction temperature was arranged in the range from 175°C to 350°C. The carbon content of coals used in the experiment was between 70% and 80%.In the case of reaction of Ube Coal having carbon content of 70.0% with sodium hydroxide, the yield of humic acid was maximum, about 55%, at 250°C; and that of residual coal (the unreacted) was minium, about 17%, at 300°C.Reactivity of potassium hydroxide with coal was greater than sodium hydroxide at the same temperature.The following results depended on the degree of the carbon content of sample coals were obtained:(1) C>80%(a) The yield of humic acid was very low.(b) The carbon content of residual coal was similar to that of the original coal.(2) C=77-80%(a) The yield of humic acid was low with sodium hydroxide at 250°C, while very high with potassium hydroxide at 300°C.(b) Even in the case of the low yield of humic acid, the carbon content of residual coal was higher than that of the original coal.(3) C<76%(a) The yield of humic acid was high.(b) The carbon content of residual coal was higher than that of the original coal.It was remarkable that the carbon content of the regenerated humic acid obtained from coal by alkaline fusion method was more than 70%, and different from the humic acid obtained from the other ordinary oxidation methods.