Time-dependent leaching of coal fly ash by chelating agents

TLDR: The rates of leaching of several transition-metal ions from coal fly ash by pH 7.4 solutions of the chelating agents citric acid, EDTA, Listidine and glycine have been measured as part of an investigation of the potential health effects of inhaled fly ash.

Abstract: The rates of leaching of several transition-metal ions from coal fly ash by pH 74 solutions of the chelating agents citric acid, EDTA, Listidine and glycine have been measured as part of an investigation of the potential health effects of inhaled fly ash The results are compared to leaching of the same fly ash by 05M HCl, 010 M pH 74 Tris buffer, 05 M NH/sub 4/OH, and canine serum For the trace elements, Zn, Mn, G, Ni, and Cu, the initial leaching rates with 05 M HCl range from 350 to 850 ppm/d The rates drop by 1-2 orders of magnitude within 24 h and then level off at 1-10 ppm/d The initial rates with EDTA and citric acid are also high, 100-400 ppm/d, but they fall off even more rapidly than the HCl leaching rates The leaching of vanadium is exceptionally rapid, with initial rates of 1000-3000 ppm/d