AVS 65th International Symposium & Exhibition
    Applied Surface Science Division Wednesday Sessions
       Session AS+NS+SA-WeM

Paper AS+NS+SA-WeM6
Speciation and Reactivity of Organic Matter in Uranium Mine Wastes from Laguna- New Mexico: An Application of Surface Sciences in Environmental Systems.

Wednesday, October 24, 2018, 9:40 am, Room 204

Session: Beyond Traditional Surface Analysis
Presenter: Carmen A. Velasco, University of New Mexico
Authors: C.A. Velasco, University of New Mexico
A.M. Ali, University of New Mexico
C. Osburn, North Carolina State University
K. Artyushkova, University of New Mexico
J.M. Cerrato, University of New Mexico
Correspondent: Click to Email
The co-occurrence of organic matter and uranium in the Jackpile Morrison formation, New Mexico was investigated using spectroscopy, microscopy, and water chemistry techniques to better understand the effects of organic matter on uranium (U) binding from abandoned U mine wastes. Samples were collected from the Jackpile Mine (JP)- New Mexico. The mean concentration of acid extractable content for mine waste from the JP was 2.61±0.09% U. Results from microprobe mapping suggest that U particles are surrounded by carbon (C) inclusions, while results from XRF analyses showed 2.78% (JP) carbon (C). Loss on ignition (LOI) analysis showed that 19.90±0.95% of organic carbon within the samples. Thermal gravimetric analysis (TGA) show the maximum weight loss between 105°C and 505°C, confirming that change on mass after the LOI is likely due to the loss of organic content of the samples. Analyses using XPS suggest that changes occur on the C binding and U oxidation state after modifying the pH in batch experiments. Emission Matrix (EMM) identified humic-acid and fulvic-acid like components present in the organic matter comprised in the mine waste, which is consistent with the organic functional groups detected by XPS. These findings suggest that uranium minerals are possibly complexed carboxylic functional groups from humic-and fulvic like substances. This study identified the relevance of considering the binding of U and C in mine wastes to better understand U mobilization in the environment.
*This work was awarded the best talk award at the 2018 NMAVS Symposium (Albuquerque-May2018)