Aqueous extraction of anions from coal and fly ash followed by ion-chromatographic determination

• Main Authors: Tasić Aleksandra M., Sredović-Ignjatović Ivana D., Ignjatović Ljubiša M., Đuranović Danijel, Antić Mališa P.
• Format: Article
• Language: English
• Published: Serbian Chemical Society 2016-01-01
• Series: Journal of the Serbian Chemical Society
• Subjects: coal; fly ash; anions; extraction; ion chromatography
• Online Access: http://www.doiserbia.nb.rs/img/doi/0352-5139/2016/0352-51391600086T.pdf

Three different techniques were applied for the aqueous extraction of anions from coal and fly ash: rotary mixer- and ultrasonic-assisted extraction with different duration time, and microwave-assisted extraction at different temperatures. Validation showed that the ion-chromatographic method was suitable for the analysis of anions in coal and fly ash extracts. The variations in the amounts of anions using different extraction times during rotary-assisted extraction were minimal for all investigated anions. The efficiency of ultrasound-assisted extraction of anions from coal depended on the sonication time and was highest at 30 min. The ultrasound-assisted extraction was less efficient for the extraction of anions from fly ash than rotary-assisted extraction. Increase of temperature in the microwave-assisted extraction had a positive effect on the amounts of all anions extracted from coal and sulphate from fly ash, while the amounts of fluoride and chloride in fly ash extracts decreased. The microwave-assisted extraction of coal at 150°C was compared with standard ASTM methods, and results were in good agreement only for chloride. Changes in the pH value and conductivity during ultrasound-assisted extraction were measured in order to explain changes on the surface of coal particles in contact with water and different processes that occur under environmental conditions. [Projekat Ministarstva nauke Republike Srbije, br. 172030, br. 176006 i br. III43009]