Determination of chloride, nitrite, nitrate and sulfate ions in water extract of coal by ion chromatography.

HONMA Haruo, SUZUKI Keiko, YOSHIDA Mutsuko, YANASHIMA Hisako

doi:10.2116/bunsekikagaku.37.4_t55

A method for the determination of free anions in coal was developed. The qualitative analysis was performed by ion chromatography for the water extracts from two kinds of coal which were commercially available as standard samples for elemental analysis. Chloride, nitrite, nitrate and sulfate ions could be detected as main anions. To extract these anions completely, 100200 mg of each kind of coal was weighed in a quartz flask, 20 ml of deionized water was added and this mixture was refluxed with a quartz condenser for 60 min. After the coal was separated by filtration, the extract was diluted with 8 mM Na₂CO₃-NaHCO₃ solution to 50.000 g and injected into the ion chromatograph. The precision of the results was good for chloride and sulfate ions, but not satisfactory for nitrite and nitrate ions. To determine the total amount of anions, the coals combusted gaseous products were absorbed in deionized water, the residue was stirred with deionized water and heated on a water bath. Each solution was injected into the ion chromatograph and the total amount of anions was obtained by adding both results. It was found that the amounts of free anions were 010% of those of the total anions. These values were useful as an indicator of the quality of coal.

Determination of chloride, nitrite, nitrate and sulfate ions in water extract of coal by ion chromatography.

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