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Selenium Adsorption To Aluminum-Based Water Treatment Residuals
Ippolito, J. A., K. G. SCHECKEL, AND K. A. Barbarick. Selenium Adsorption To Aluminum-Based Water Treatment Residuals. D. T. Wasan (ed.), JOURNAL OF COLLOID AND INTERFACE SCIENCE. ELSEVIER, AMSTERDAM, Holland, 338(1):48-55, (2009).
To determine if Al-based WTR could sequester Se(VI) and Se(IV), and to identify Se adsorption chemistries onto the mineral phases present in WTR.
Aluminum-based water treatment residuals (WTR) can adsorb water-and soil-borne P, As(V), As(III), and perchlorate, and may be able to adsorb excess environmental selenium. WTR, clay minerals, and amorphous aluminum hydroxide were shaken for 24 hours in selenate or selenite solutions at pH values of 5 to 9, and then analyzed for selenium content. Selenate and selenite adsorption edges were unaffected across the pH range studied. Selenate adsorbed on to WTR, reference mineral phases, and amorphous aluminum hydroxide occurred as outer sphere complexes (relatively loosely bound), while selenite adsorption was identifed as inner sphere complexation (relatively tightly bound). Selenite sorption to WTR in an anoxic environment reduced Se(IV) to Se(0), and oxidation of Se(0) or Se(IV) appeared irreversible once sorbed to WTR. Al-based WTR could play a favorable role in sequestering excess Se in affected water resources.