URANIUM SORPTION UTILIZING CLAY PELLETS TO PRODUCE POTABLE WATER ON THE NAVAJO NATION: PURSUING A SURROGATE CATION TO MODEL URANIUM ABATEMENT
Ryan Yazzie, Antonio S. Lara.
New Mexico State University, Las Cruces, NM.
Many water sources on the Navajo Nation which straddles Arizona, Utah, New Mexico, and Colorado are contaminated with high concentrations of uranium. Some uranium concentrations exceed the safe drinking water level established by the United States Environmental Protection Agency (EPA) and the World Health Organization, 30 ppb and 15 ppb respectively. A study by the EPA Region 9 included 36 unregulated water samples; 5 water sources (14%) in 5 chapters exceeded the maximum concentration levels (MCL) for uranium. Clay pellets are an appropriate solution to remove uranium from polluted water sources to provide potable water. Our research objectives are two-fold: 1) that the final uranium concentrations are acceptable and at safe drinking water limits; and 2) find a surrogate for uranium because direct uranium studies are potentially dangerous and expensive. Therefore, we will investigate iron (II) bromide, iron (III) bromide, cobalt chloride, copper (II) acetate and cupric sulfate to find the best metal cation that mimics uranium abatement, and we propose an S-curve adsorption isotherm. Handheld colorimeters and fluorometry will be used to probe kinetics and thermodynamics for surrogate and uranium adsorption. We anticipate that uranium and surrogate adsorption will be optimal in a pH range of 1 to 6 and a redox potential range of 0.2 to 1.4.