title: Reductive immobilization of pertechnetate in soil and groundwater using synthetic pyrite nanoparticles.
abstract: Radioactive technetium (99Tc) is of intense concern because of its toxicity and high mobility in the environment. Reduction of Tc(VII) to Tc(IV) decreases the mobility and availability of technetium in soil and groundwater. In this study, pyrite nanoparticles (FeS2) were synthesized, characterized and tested for immobilizing/removing99Tc(VII) in soil and groundwater through batch and column experiments. Influences of particle dosage, dissolved organic matter (DOM), and pH on the reductive immobilization kinetics were examined. At a dosage of 0.28 g/L as Fe, the pyrite nanoparticles were able to rapidly and completely remove 4.88 × 10-7M of Tc(VII) by converting it to insoluble Tc(IV), with a retarded first-order rate constant of 0.30 h-1. The presence of high concentrations of DOM only moderately inhibited the reduction effectiveness, and acidic pH was more favorable for Tc(VII) reduction. Column experiments showed that embedding a 0.8 cm pyrite layer of the material in a soil bed, simulating a permeable reactive barrier, was able to retard technetium transport 710 times more than a model sandy soil. The results demonstrated that the pyrite particles may serve as a long-lasting reactive material to remediate Tc-contaminated soil, groundwater and solid wastes.
authors.affiliation: College of Environment and Safety, Taiyuan University of Science and Technology, Taiyuan, Shanxi, 030024, China; Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
authors.forename: Lijuan
authors.initials: L
authors.lastname: Huo
authors.affiliation: Environmental Engineering Program, Department of Civil Engineering, 238 Harbert Engineering Center, Auburn University, Auburn, AL 36849, USA.
authors.forename: Wenbo
authors.initials: W
authors.lastname: Xie
authors.affiliation: College of Environment and Safety, Taiyuan University of Science and Technology, Taiyuan, Shanxi, 030024, China.
authors.forename: Tianwei
authors.initials: T
authors.lastname: Qian
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Guan
authors.affiliation: College of Environment and Safety, Taiyuan University of Science and Technology, Taiyuan, Shanxi, 030024, China; Environmental Engineering Program, Department of Civil Engineering, 238 Harbert Engineering Center, Auburn University, Auburn, AL 36849, USA. Electronic address: zhaodon@auburn.edu.
authors.forename: Dongye
authors.initials: D
authors.lastname: Zhao
mesh_terms: D060587:Groundwater / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D013670:Sodium Pertechnetate Tc 99m / Q000737:chemistry* / Q000302:isolation & purification; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000737:chemistry* / Q000302:isolation & purification; D013440:Sulfides / Q000138:chemical synthesis / Q000737:chemistry*; D014875:Water Pollutants, Radioactive / Q000737:chemistry* / Q000302:isolation & purification
chemical_list: D012987:Soil; D012989:Soil Pollutants; D013440:Sulfides; D014875:Water Pollutants, Radioactive; C011342:pyrite; D013670:Sodium Pertechnetate Tc 99m; D007501:Iron
keywords: Groundwater remediation; Pyrite; Radionuclide; Reductive immobilization; Soil remediation; Technetium