102767 Effects of pH and Nitrate on Perrhenate Sorption in Zerovalent Iron.

Poster Number 467-327

See more from this Division: SSSA Division: Soil Chemistry
See more from this Session: Soil Chemistry Poster

Wednesday, November 9, 2016
Phoenix Convention Center North, Exhibit Hall CDE

Yuji Arai, Dept of Nat Res & Environ Sci, University of Illinois-Urbana-Champaign, Urbana, IL and Brian Lenell, University of Illinois at Urbana-Champaign, Urbana, IL
Abstract:
Technetium(Tc)-99 is one of major risk drivers in low level radioactive liquid waste at the U.S. Department of Energy sites. Cementitious waste technology (CWT) has been considered immobilizing pertechnetate, Tc(VII)O4-, in brine and alkaline wastes, as Tc(IV) oxides and/or sulfides with the use of reducing agents like slag. In this study, zero valent iron (ZVI) was evaluated as a potential reducing agent for Tc(VII) as a function of pH and [nitrate] (0-0.1M). Batch Re(VII)O4- (i.e.,   as an analogue for Tc(VII)O4-) sorption experiments and X-ray absorption spectroscopic analysis showed that the Re(VII) sorption occurred via the reductive precipitation of Re(IV)O2(s) and the extent of sorption decreased with increasing pH from 8 to 10. Interestingly, pseudo 2nd order kinetic rates increased with increasing [nitrate] which was attributed to co-adsorption of NH4+ (i.e., a reaction product of reduced nitrate by ZVI), facilitating electrostatic attraction towards ReO4- under alkaline conditions. Considering the thermodynamically favorable reduction of Tc(VII) over Re(VII),  ZVI might have potential for improving the reduction capacity of the current immobilization method.

See more from this Division: SSSA Division: Soil Chemistry
See more from this Session: Soil Chemistry Poster