Study Of The Extraction Of Fulvic Acid From Weathered Coal

Sulfuric acid method, base-dissolving acidification method, ion exchange resin method, and acetone-sulfuric acid method were studied in this paper for extraction of fulvic acid from weathered coal in which the content of humic acid is high, fulvic acid is low.The four effect factors of Sulfuric acid method, including reaction time, solvent-to-solid ratio, acid-to-coal ratio, and ultrasonic, were investigated. Under the optimum condition, the rate of extraction was less than 8%.The base-dissolving acidification method was studied by changing the pH when the reaction finished. Under the optimum condition, the rate of extraction was less than 10%.The ion exchange resin method was studied by changing the weight ratio of resin to coal when the reaction finished. Under the optimum condition, the rate of extraction was less than 7%.The effect of four factors, reaction time, solvent-to-solid ratio, acid-to-coal ratio and the water content in extraction mixture, were studied on the extraction rate of acetone-sulfuric acid method. The results showed that the optimum extraction conditions as follows: the water content was 10%, acid-to-coal ratio was 0.05, solid-to-solvent ratio was 7.5, and reaction time was 30 minutes. Under these conditions, the extraction rate was 41%, the humic acid content 78.8%, the fulvic acid content 43.4%, ash content 1.53%, moisture content 6.8%, water-insoluble 60%.The acetone-sulfuric acid method was further studied by comparison of FA extraction rate with HA extraction rate. When acid-to-coal ratio, solvent-to-solid ratio, reaction time changed respectively, the change trends of FA and HA extraction rate were generally similar. When the water content in extraction mixture changed, the extraction rate of HA gradually declined, while the extraction rate of FA declined first and increased later.The structure of FA was also studied by IR and the result is in accord with documents.