MOBILIZATION AND CHARACTERIZATION OF COLLOIDS GENERATED FROM CEMENT LEACHATES MOVING THROUGH A SRS SANDY SEDIMENT

Li, D. ; Roberts, K. ; Kaplan, D. ; Seaman, J.

关键词: AR FACILITIES;    CATIONS;    CEMENTS;    COLLOIDS;    LEACHATES;    PLUMES;    POROUS MATERIALS;    RADIOISOTOPES;    RADIONUCLIDE MIGRATION;    SAVANNAH RIVER PLANT;    SEDIMENTS;    SUBSURFACE STRUCTURES;    TRANSPORT;    VECTORS;    X-RAY DIFFRACTION;   

DOI  :  10.2172/1030793
RP-ID  :  SRNL-STI-2011-00498
PID  :  OSTI ID: 1030793
Others  :  TRN: US1200066

美国|英语

来源: SciTech Connect

【 摘 要 】

Naturally occurring mobile colloids are ubiquitous and are involved in many important processes in the subsurface zone. For example, colloid generation and subsequent mobilization represent a possible mechanism for the transport of contaminants including radionuclides in the subsurface environments. For colloid-facilitated transport to be significant, three criteria must be met: (1) colloids must be generated; (2) contaminants must associate with the colloids preferentially to the immobile solid phase (aquifer); and (3) colloids must be transported through the groundwater or in subsurface environments - once these colloids start moving they become 'mobile colloids'. Although some experimental investigations of particle release in natural porous media have been conducted, the detailed mechanisms of release and re-deposition of colloidal particles within natural porous media are poorly understood. Even though this vector of transport is known, the extent of its importance is not known yet. Colloid-facilitated transport of trace radionuclides has been observed in the field, thus demonstrating a possible radiological risk associated with the colloids. The objective of this study was to determine if cementitious leachate would promote the in situ mobilization of natural colloidal particles from a SRS sandy sediment. The intent was to determine whether cementitious surface or subsurface structure would create plumes that could produce conditions conducive to sediment dispersion and mobile colloid generation. Column studies were conducted and the cation chemistries of influents and effluents were analyzed by ICP-OES, while the mobilized colloids were characterized using XRD, SEM, EDX, PSD and Zeta potential. The mobilization mechanisms of colloids in a SRS sandy sediment by cement leachates were studied.