Publication Date

5-2011

Advisor(s) - Committee Chair

Dr. Wei-Ping Pan (Director), Dr. Bangbo Yan, Dr. Eric Conte, Dr. Yan Cao

Degree Program

Department of Chemistry

Degree Type

Master of Science

Abstract

An approach to arsenic and selenium removal from fly ash is studied. This research includes a comparison of the leaching ability of ammonium oxalate, ammonium citrate, ammonium nitrate and EDTA to extract arsenic and selenium; use of common agricultural waste as a source of oxalate anion to remove arsenic and selenium from fly ash and estimation of additional calcium effects on arsenic and selenium leaching behaviors.
This research shows that extraction strength order is EDTA > ammonium oxalate > ammonium citrate > ammonium nitrate > water, achieving arsenic extraction efficiencies of 94.18%, 84.17%, 4.50%, 2.89% and 0.18%, respectively; achieving selenium extraction efficiencies of 96.14%, 96.26%, 84.34%, 26.60% and 0.71%,respectively, in single-stage extraction. Tall fescue is applied as a source of natural oxalate resource and is able to remove over 70% of arsenic and selenium from fly ash. Additional calcium is found to make 82.20% of total arsenic in free oxalate leachate drop to 1.65% of total arsenic in free oxalate and free calcium leachate. All samples were analyzed using HG-AFS.
Hopefully, this research will be helpful when a large scale, cheap and sustainable fly ash clean-up approach is needed for power plants prior to landfilling. Also, calcium effects will enable arsenic and selenium to move to the solid phase and could possibly solve the problem of toxic wastewater generated from the clean-up process. The enriched toxic solid waste could be used for pesticide applications.

Disciplines

Environmental Chemistry | Organic Chemistry | Soil Science