4.8 Article

Synergistic Enhancement of Lead and Selenate Uptake at the Barite (001)-Water Interface

期刊

ENVIRONMENTAL SCIENCE & TECHNOLOGY
卷 56, 期 23, 页码 16801-16810

出版社

AMER CHEMICAL SOC
DOI: 10.1021/acs.est.2c04413

关键词

sorption; incorporation; thin film formation; lead; selenate; barite; fate and transport of contaminants

资金

  1. U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division
  2. Argonne National Laboratory [DE-AC02-06CH11357]
  3. Office of Science of the U.S. Department of Energy [DE-AC05-00OR22725]
  4. National Energy Research Scientific Computing Center (NERSC)
  5. U.S. Department of Energy Office of Science User Facility [DE-AC02-05CH11231]
  6. NERSC award [BES-ERCAP-0020278]
  7. U.S. Department of Energy Office of Science laboratory

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The study found synergistically enhanced uptake of lead and selenate on the barite surface through multiple mechanisms, with increasing co-sorbed ion coverages leading to a systematic increase in sorption affinity. Computational simulations showed thermodynamically favorable co-incorporation of lead and selenate on the mineral surface.
The interactions of heavy metals with minerals influence the mobility and bioavailability of toxic elements in natural aqueous environ-ments. The sorption of heavy metals on covalently bonded minerals is generally well described by surface complexation models (SCMs). However, understanding sorption on sparingly soluble minerals is challenging because of the dynamically evolving chemistry of sorbent surfaces. The interpretation can be even more complicated when multiple metal ions compete for sorption. In the present study, we observed synergistically enhanced uptake of lead and selenate on the barite (001) surface through two sorption mechanisms: lattice incorporation that dominates at lower coverages and two-dimensional monolayer growth that dominates at higher coverages. We also observed a systematic increase in the sorption affinity with increasing co-sorbed ion coverages, different from the assumption of invariant binding constants for individual adsorption processes in classical SCMs. Computational simulations showed thermodynamically favorable co-incorporation of lead and selenate by simultaneously substituting for barium and sulfate in neighboring sites, resulting in the formation of molecular clusters that locally match the net dimension of the substrate lattice. These results emphasize the importance of ion-ion interactions at mineral-water interfaces that control the fate and transport of contaminants in the environment.

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