Chemical controls on the solubility, transport and deposition of platinum and palladium in hydrothermal solutions; a thermodynamic approach

Mountain, Bruce W.; Wood, Scott A.

doi:10.2113/gsecongeo.83.3.492

Cited by 187 publications

(102 citation statements)

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“…Potential Pt(II) complexes present in the reactions systems included Pt(II), Pt(OH)n −2+n and PtCln −2+n . Likely Pt(IV) compounds included Pt(IV), Pt(OH)n −4+n and PtCln −4+n , but very little data exists for these species [29,30,34,37,53]. EXAFS confirmed platinum-chloride to be the dominant aqueous species prior to (A) XANES spectra of bacteria reacted with 5000 µM Pt(II) and Pt(IV) solutions for up to 28 days.…”

Section: Discussionmentioning

confidence: 99%

“…Under surficial weathering conditions, the predicted oxidation state of platinum in aqueous solutions is Pt(II) or Pt(IV) [29]. Based on thermodynamic calculations, platinum is likely to occur as free aqueous ions only in oxidising and acidic environments, therefore, under most surficial conditions, platinum occurs as stable colloids/nanoparticles or is bound by coordination complexes to organic and inorganic ligands [29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

“…Platinum commonly forms complexes with chlorides, hydroxides and thiosulphates, but amorphous organo-platinum and platinum-hydroxide colloids also occur [29,30,[32][33][34][35][36]. Aqueous platinum is transported in the surficial environment until conditions favour its (biogeo)chemical transformation and/or chemical precipitation.…”

Section: Introductionmentioning

confidence: 99%

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Immobilisation of Platinum by Cupriavidus metallidurans

et al. 2018

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Abstract:The metal resistant bacterium Cupriavidus metallidurans CH34, challenged with aqueous platinous and platinic chloride, rapidly immobilized platinum. XANES/EXAFS analysis of these reaction systems demonstrated that platinum binding shifted from chloride to carboxyl functional groups within the bacteria. Pt(IV) was more toxic than Pt(II), presumably due to the oxidative stress imparted by the platinic form. Platinum immobilisation increased with time and with increasing concentrations of platinum. From a bacterial perspective, intracellular platinum concentrations were two to three orders of magnitude greater than the fluid phase, and became saturated at almost molar concentrations in both reaction systems. TEM revealed that C. metallidurans was also able to precipitate nm-scale colloidal platinum, primarily along the cell envelope where energy generation/electron transport occurs. Cells enriched in platinum shed outer membrane vesicles that were enriched in metallic, colloidal platinum, likely representing an important detoxification strategy. The formation of organo-platinum compounds and membrane encapsulated nanophase platinum, supports a role for bacteria in the formation and transport of platinum in natural systems, forming dispersion halos important to metal exploration.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Immobilisation of Platinum by Cupriavidus metallidurans

et al. 2018

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“…L'étage d'oxydation prédominant pour le Pt est +2 (Mountain et Wood 1988a, b), tandis que celui de l'or est +1 (Shenberger and Barnes 1989;Benedetti et Boulègue 1991).…”

Section: Rôle De La Matière Organiqueunclassified

“…Les complexes chlorurés sont souvent mis en avant comme responsables de la mise en solution des EGP et de l'Au sous les conditions oxydantes et acides (Mann 1984;Jaireth 1988;Tait et al 1991;Mountain and Wood 1988a;Plimerand William 1988;Wood et al 1989;Wood et al 1992;Gammons et al 1992;Jaireth 1992). Il ressort de toutes ces études que sous les conditions de basse température, la formation des complexes chlorurés du Pt et du Pd reste limitée aux milieux acides (pH < 4) et extrêmement oxydants (hématite stable), que l'on peut retrouver dans la CU.…”

Section: Rôle Des Complexes Chlorurésunclassified