SIR Chemistry Investigation Abstract
METHODS TO REMOVE CARCINOGENIC ARSENIC FROM GROUNDWATER USING MINERAL OXIDES AND CITRATE TO SEQUESTER ARSENIC(III)
Presenter:
Yuxi Ji, Illinois Mathematics and Science Academy
Advisor:
Professor Jean-Francois Gaillard, Northwestern University
Abstract:
Arsenic poses significant health problems to humans. It is an element present in soils at many contaminated sites and in aquatic systems as a result of either anthropogenic activities or natural processes. In the environment, arsenic is present as As(III) and As(V). It forms different chemical species of varying toxicity and mobility. In contrast to organic pollutants, arsenic cannot be destroyed, only its speciation can be modified. This speciation will change as a result of reactions with oxygen.
In Bangladesh, arsenic is present in drinking water at concentrations that affect human health. The goal of this research is to determine how arsenic could be removed from drinking water by using benign chemicals. In the laboratory, we have recreated the chemical composition of Bangladesh groundwater and are studying the removal of As(III) by the natural precipitation of oxides. The oxidation of As(III) to As(V) is facilitated by the presence of citrate that forms a complex with iron that is photoactive. With exposure to oxygen and sunlight, Fe(II) will oxidize to Fe(III) and form Fe(OH)3, whereas As(III) is oxidized to As(V) that is sorbed onto Fe(OH)3 precipitates. After filtration, the water contains reduced levels of total dissolved arsenic.