Effects of NaOH Solution Concentration on the Determination of Free Humic Acid Content in Coal
The weathered coal and lignite from different origins were extracted with 0.2%,0.5%and 1.0%NaOH solutions to detect the content of free humic acid and to verify the effects of NaOH solution concentration on the determination of free humic acid content in coal.The results showed that the results of 1.0%NaOH solution as the extraction agent were lower than those of 0.2%and 0.5%for weathered coal.The results of the extraction with different concentrations of NaOH solution were not different for lignite.