Enhanced release of palladium and platinum from catalytic converter materials exposed to ammonia and chloride bearing solutions

Deborah M. Aruguete, Mitsuhiro Murayama, Terry Blakney, Christopher Winkler

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

The environmental levels of platinum group elements (PGEs) are steadily rising, primarily due to exhaust emissions of vehicle catalytic converter (VCC) materials containing solid PGEs. Once these VCC materials reach soil and water, the PGEs may be transported in the form of nanoparticles (dimensions 1-100 nm) or they may be mobilized by forming coordination complexes with ligands in the environment. Chloride (Cl - ) and ammonia (NH 3 ) are two ligands of particular concern due to their ubiquity as well as their potential to form the chemotherapy drug cisplatin (Pt(NH 3 ) 2 Cl 2 ) or other potentially bioactive complexes. This initial study examines the release of Pd and Pt into solutions exposed to VCC materials at pH 8 and 25 °C, using elemental analysis of metal content in post-exposure extracts. The solutions had total ammonia nitrogen concentrations (TAN, [NH 4 + ] + [NH 3 ]) of 0 μM, 5.56 μM, 55.6 μM and 1.13 × 10 5 μM (0 ppm, 0.1 ppm, 1 ppm, and 2147 ppm). The former three represent background environmental levels had a minimal effect on release. However, when combined with 1.13 × 10 5 μM Cl - (4000 ppm Cl - ), 55.6 μM TAN induced a marked increase in metal release (∼41× for Pd). High TAN solutions induced more Pd and Pt release than equimolar NaCl solutions. Materials characterization revealed that ∼4 nm palladium-containing nanoparticles were present, spatially associated with nanoparticles of γ-Al 2 O 3 ; ceria-zirconia nanoparticles were also present but did not have any metal associated with them. Platinum-containing nanoparticles were not observed.

Original languageEnglish (US)
Pages (from-to)133-144
Number of pages12
JournalEnvironmental Science: Processes and Impacts
Volume21
Issue number1
DOIs
StatePublished - Jan 2019

Fingerprint

Bearings (structural)
Catalytic converters
palladium
Palladium
Platinum
platinum
Ammonia
Triacetoneamine-N-Oxyl
Nanoparticles
Chlorides
ammonia
chloride
platinum group element
Metals
ligand
metal
Ligands
Vehicle Emissions
chemotherapy
exhaust emission

All Science Journal Classification (ASJC) codes

  • Environmental Chemistry
  • Public Health, Environmental and Occupational Health
  • Management, Monitoring, Policy and Law

Cite this

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title = "Enhanced release of palladium and platinum from catalytic converter materials exposed to ammonia and chloride bearing solutions",
abstract = "The environmental levels of platinum group elements (PGEs) are steadily rising, primarily due to exhaust emissions of vehicle catalytic converter (VCC) materials containing solid PGEs. Once these VCC materials reach soil and water, the PGEs may be transported in the form of nanoparticles (dimensions 1-100 nm) or they may be mobilized by forming coordination complexes with ligands in the environment. Chloride (Cl - ) and ammonia (NH 3 ) are two ligands of particular concern due to their ubiquity as well as their potential to form the chemotherapy drug cisplatin (Pt(NH 3 ) 2 Cl 2 ) or other potentially bioactive complexes. This initial study examines the release of Pd and Pt into solutions exposed to VCC materials at pH 8 and 25 °C, using elemental analysis of metal content in post-exposure extracts. The solutions had total ammonia nitrogen concentrations (TAN, [NH 4 + ] + [NH 3 ]) of 0 μM, 5.56 μM, 55.6 μM and 1.13 × 10 5 μM (0 ppm, 0.1 ppm, 1 ppm, and 2147 ppm). The former three represent background environmental levels had a minimal effect on release. However, when combined with 1.13 × 10 5 μM Cl - (4000 ppm Cl - ), 55.6 μM TAN induced a marked increase in metal release (∼41× for Pd). High TAN solutions induced more Pd and Pt release than equimolar NaCl solutions. Materials characterization revealed that ∼4 nm palladium-containing nanoparticles were present, spatially associated with nanoparticles of γ-Al 2 O 3 ; ceria-zirconia nanoparticles were also present but did not have any metal associated with them. Platinum-containing nanoparticles were not observed.",
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Enhanced release of palladium and platinum from catalytic converter materials exposed to ammonia and chloride bearing solutions. / Aruguete, Deborah M.; Murayama, Mitsuhiro; Blakney, Terry; Winkler, Christopher.

In: Environmental Science: Processes and Impacts, Vol. 21, No. 1, 01.2019, p. 133-144.

Research output: Contribution to journalArticle

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