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Selenium-Water Treatment Residual Adsorption And Characterization
Citation:
Ippolito, J., K. G. SCHECKEL, AND K. Barbarick. Selenium-Water Treatment Residual Adsorption And Characterization. Presented at Annual Meeting Of The Soil Science Society Of America, Houston, TX, October 05 - 11, 2008.
Impact/Purpose:
To determine Se speciation by analyzing all samples using XAS method.
Description:
Aluminum-based water treatment residuals (WTR) have the ability to adsorb tremendous quantities of soil-borne P, and have been shown to adsorb other anions, such as As (V), As (III), and ClO4-. Environmental issues associated with Se in the Western US led us to study WTR sorption of Se (VI) and Se (IV). The WTR were mixed with either Na2SeO4 (Se (VI)) or Na2SeO3 (Se (IV)) at a Se concentration of 60 mg L-1. Solution pH was varied from 5 to 9, and triplicate samples of WTR-Se (VI) (exposed to atmospheric conditions) and WTR-Se (IV) (exposed to an N2 atmosphere to control redox) were shaken for 24 hours. All samples were centrifuged, the solution discarded, and the WTR-Se (VI) mixtures were allowed to dry under atmospheric conditions, while the WTR-Se (IV) mixtures were dried in an anaerobic glove bag. An additional set of WTR-Se (IV) redox controlled treatments were reacted for 24 hours at pH 7, exposed to compressed air for 1, 2, 4, 7, 14, and 28 day(s), then centrifuged and allowed to dry under atmospheric conditions. All samples were analyzed using XAS to detemine Se speciation. Results will be discussed.