Time-dependent leaching of coal fly ash by chelating agents

Journal Article · Tue Mar 01 04:00:00 EST 1983 · Environ. Sci. Technol.; (United States)

DOI:https://doi.org/10.1021/es00109a004· OSTI ID:5130161

Harris, W R; Silberman, D

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, histidine, and glycine have been measured. These results are compared to leaching of the same fly ash by 0.5 M HCl, 0.10 M pH 7.4 Tris buffer, 0.5 M NH/sub 4/OH, and canine serum. The general order of leaching ability is HCl>>EDTA approx. citric acid > histidine > glycine approx. Tris. Canine serum is more effective as a leaching agent than one would predict on the basis of its concentrations of citrate and histidine, so that other biological chelators, possibly cysteine, appear to be important leaching agents. For the trace elements Zn, Mn, Cr, Ni, and Cu, the initial leaching rates with 0.5 M HCl range from 350 to 850 ..mu..g of metal per gram of ash per day (ppm/day). The rates drop by 1-2 orders of magnitude within 24 h and then level off at 1-10 ppm/day. The initial rates with EDTA and citric acid are also high, approx.100-400 ppm/day, 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/day. In addition, EDTA and citric acid leach over 50% of the acid-soluble vanadium compared to only 10-35% of the other transition metals.

• Research Organization: Univ. of California, Davis
• OSTI ID: 5130161
• Journal Information: Environ. Sci. Technol.; (United States), Journal Name: Environ. Sci. Technol.; (United States) Vol. 17:3; ISSN ESTHA
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010800 -- Coal
Lignite
& Peat-- Waste Management
500200* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
AEROSOL WASTES
AIR POLLUTION
AMINO ACIDS
ASHES
AZOLES
CARBONACEOUS MATERIALS
CARBOXYLIC ACIDS
CHELATING AGENTS
CITRIC ACID
COAL
CONCENTRATION RATIO
DISSOLUTION
ELEMENTS
ENERGY SOURCES
FLY ASH
FOSSIL FUELS
FUELS
GLYCINE
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HISTIDINE
HYDROXY ACIDS
IMIDAZOLES
LEACHING
MATERIALS
METALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PH VALUE
POLLUTION
RESIDUES
SEPARATION PROCESSES
TIME DEPENDENCE
TRACE AMOUNTS
TRANSITION ELEMENTS
WASTES