Anionic sorbents for arsenic and technetium species.

Lucero, Daniel A. ; Moore, Robert Charles ; Bontchev, Ranko Panayotov ; Hasan, Ahmed Ali Mohamed ; Zhao, Hongting ; Salas, Fred Manuel ; Holt, Kathleen Caroline

Sandia National Laboratories

关键词: Materials Testing;    Zirconium;    Zeolites;    Technetium-Absorption And Adsorption.;    Reaction Kinetics;   

DOI  :  10.2172/917480
RP-ID  :  SAND2003-3360
RP-ID  :  AC04-94AL85000
RP-ID  :  917480

美国|英语

来源: UNT Digital Library

【 摘 要 】

Two sorbents, zirconium coated zeolite and magnesium hydroxide, were tested for their effectiveness in removing arsenic from Albuquerque municipal water. Results for the zirconium coated zeolite indicate that phosphate present in the water interfered with the sorption of arsenic. Additionally, there was a large quantity of iron and copper present in the water, corrosion products from the piping system, which may have interfered with the uptake of arsenic by the sorbent. Magnesium hydroxide has also been proven to be a strong sorbent for arsenic as well as other metals. Carbonate, present in water, has been shown to interfere with the sorption of arsenic by reacting with the magnesium hydroxide to form magnesium carbonate. The reaction mechanism was investigated by FT-IR and shows that hydrogen bonding between an oxygen on the arsenic species and a hydrogen on the Mg(OH)2 is most likely the mechanism of sorption. This was also confirmed by RAMAN spectroscopy and XRD. Technetium exists in multiple oxidation states (IV and VII) and is easily oxidized from the relatively insoluble Tc(IV) form to the highly water soluble and mobile Tc(VII) form. The two oxidation states exhibit different sorption characteristics. Tc(VII) does not sorb to most materials whereas Tc(IV) will strongly sorb to many materials. Therefore, it was determined that it is necessary to first reduce the Tc (using SnCl2) before sorption to stabilize Tc in the environment. Additionally, the effect of carbonate and phosphate on the sorption of technetium by hydroxyapatite was studied and indicated that both have a significant effect on reducing Tc sorption.