Influence of Surface Compositions on the Reactivity of Pyrite toward Aqueous U(VI) Articles uri icon

authors

  • MA, BIN
  • FERNANDEZ MARTINEZ, ALEJANDRO
  • KANG, MINGLIANG
  • WANG, KAIFENG
  • LEWIS, ALED R.
  • MAFFEIS, THIERRY G. G.
  • FINDLING, NATHANIEL
  • SALAS COLERA, EDUARDO
  • TISSERAND, DELPHINE
  • BUREAU, SARAH
  • CHARLET, LAURENT

publication date

  • July 2020

start page

  • 8104

end page

  • 8114

issue

  • 13

volume

  • 54

International Standard Serial Number (ISSN)

  • 0013-936X

Electronic International Standard Serial Number (EISSN)

  • 1520-5851

abstract

  • Pyrite plays a significant role in governing the mobility of toxic
    uranium in an anaerobic environment via an oxidation−reduction process
    occurring at the mineral−water interface, but the factors influencing the
    reaction kinetics remain poorly understood. In this study, natural pyrites with
    different impurities (Pb, As, and Si) and different surface pretreatments were
    used to react with aqueous U(VI) from pH ∼3.0 to ∼9.5. Both aqueous and
    solid results indicated that freshly crushed pyrites, which do have more surface
    Fe2+/Fe3+ and S2− sites that were generated from breakage of Fe(S)−S bonds
    during ball milling, exhibited a much stronger reactivity than those treated
    with acid washing. Besides, U(VI) reduction which involves the possible
    intermediate U(V) and the formation of hyperstoichiometric UO2+x(s) was
    found to preferentially occur at Pb- and As-rich spots on the pyrite surface,
    suggesting that the incorporated impurities could act as reactive sites because
    of the generation of lattice defects and galena- and arsenopyrite-like local
    configurations. These reactive surface sites can be removed by acid washing, leaving a pyrite surface nearly inert toward aqueous
    U(VI). Thus, reactivity of pyrite toward U(VI) is largely governed by its surface compositions, which provides an insight into the
    chemical behavior of both pyrite and uranium in various environments.

subjects

  • Materials science and engineering

keywords

  • transfer reactions; redox reactions; uranium; pyrite; x-ray photoelectron spectroscopy