1 research outputs found
Arsenic Speciation in Bituminous Coal Fly Ash and Transformations in Response to Redox Conditions
The
risk of the mobilization of coal ash into the environment has
highlighted the need for the assessment of the environmental behavior
of coal ash, particularly with respect to toxic trace elements such
as arsenic (As). Here, we examined As speciation in coal fly ash samples
and transformations in response to aquatic redox conditions. X-ray
absorption spectroscopy indicated that 92–97% of total As occurred
as AsÂ(V), with the remainder present as AsÂ(III). Major As-bearing
hosts in unamended ashes were glass, iron (oxyhydr)Âoxides, and calcium
arsenate. Oxic leaching resulted in immediate As mobilization to the
aqueous phase, reprecipitation of As-iron ferrihydrite, and As adsorption
to mineral surfaces. Under anoxic conditions, the (reductive) dissolution
of As-bearing phases such as iron ferrihydrite resulted in increased
dissolved As compared to oxic conditions and reprecipitation of iron
arsenate. Overall, As in coal ash is not environmentally stable and
can participate in local biogeochemical cycles