Reductive Immobilization of Rhenium in Soil and Groundwater Using Pyrite Nanoparticles

This study reports a method for preparation of pyrite nanoparticles and experimental results of reductive removal of perrhenate (a surrogate for radioactive pertechnetate) from water using the nanoparticles. The pyrite nanoparticles were prepared by ball milling in ethanol. Batch kinetic tests and column tests indicated that the pyrite nanoparticles were able to rapidly reduce and remove perrhenate at ambient temperatures. The pyrite nanoparticles were characterized using XRD and SEM. The effects of particle size and pH on the immobilization of perrhenate were studied in batch experiments with pyrite particles of different sizes (20 mu m and 100 nm) and under different initial pH conditions (3.5, 6.6, and 12). To probe the potential of the nanoparticles for in situ immobilization of perrhenate in soil, column tests were carried out, where the pyrite nanoparticles were packed in the column to simulate a permeable reactive barrier. The column tests showed that the pyrite nanoparticles reduced the water leachable ReO4- by 44 %. The results revealed great potential of pyrite nanoparticles for possible reductive immobilization of pertechnetate and other redox-sensitive metals and radionuclides in soil and groundwater.