Simple Extraction of Sulfite and Sulfate in Cogeneration Plant Circulating Fluidized Bed Fly Ash for Ion Chromatographic Analysis

Abstract

A simple method is described for analyses of sulfite and sulfate, in cogeneration plant fly ash/bottom ash from a coal-fired circulating fluidized bed (CFB) steam-electricity cogeneration process. Ash is shaken for 3 h (room temperature) in 3 mM disodium EDTA solution, and then the filtrate is analyzed by ion chromatography/suppressed conductivity. The EDTA slows the rate of metal ion-catalyzed sulfite oxidation by dissolved oxygen without using formaldehyde preservative. Sulfite standards in EDTA solution were stable for up to 3 days at room temperature in the presence of air. Detection limits were 0.08% by mass SO32− and 0.1 % by mass SO42− for 0.1 g fly ash extracted with 100 m1 of the EDTA reagent.