An X-ray Absorption Fine Structure study of Au adsorbed onto the non-metabolizing cells of two soil bacterial species

Song, Zhen; Kenney, Janice P.L.; Fein, Jeremy B.; Bunker, Bruce A.

doi:10.1016/j.gca.2012.02.030

Cited by 40 publications

(29 citation statements)

References 42 publications

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“…This lead to the formation of gold(I)-S cell wall complexes [52]. Further reduction to metallic gold particles was not observed, even after extended incubation periods [52].…”

Section: Cupriavidus Metallidurans Ch34-putative Co-utilization Of Otmentioning

confidence: 99%

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Geobiological Cycling of Gold: From Fundamental Process Understanding to Exploration Solutions

et al. 2013

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Microbial communities mediating gold cycling occur on gold grains from (sub)-tropical, (semi)-arid, temperate and subarctic environments. The majority of identified species comprising these biofilms are β-Proteobacteria. Some bacteria, e.g., Cupriavidus metallidurans, Delftia acidovorans and Salmonella typhimurium, have developed biochemical responses to deal with highly toxic gold complexes. These include gold specific sensing and efflux, co-utilization of resistance mechanisms for other metals, and excretion of gold-complex-reducing siderophores that ultimately catalyze the biomineralization of nano-particulate, spheroidal and/or bacteriomorphic gold. In turn, the toxicity of gold complexes fosters the development of specialized biofilms on gold grains, and hence the cycling of gold in surface environments. This was not reported on isoferroplatinum grains under most near-surface environments, due to the lower toxicity of mobile platinum complexes. The discovery of gold-specific microbial responses can now drive the development of geobiological exploration tools, e.g., gold bioindicators and biosensors. Bioindicators employ genetic markers from soils and groundwaters to provide information about gold mineralization processes, while biosensors will allow in-field analyses of gold concentrations in complex sampling media.

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“…This lead to the formation of gold(I)-S cell wall complexes [52]. Further reduction to metallic gold particles was not observed, even after extended incubation periods [52].…”

Section: Cupriavidus Metallidurans Ch34-putative Co-utilization Of Otmentioning

confidence: 99%

“…This lead to the formation of gold(I)-S cell wall complexes [52]. Further reduction to metallic gold particles was not observed, even after extended incubation periods [52]. This initial passive sorption is followed by uptake into the cytoplasm, which promotes gold toxicity [27,45].…”

Section: Cupriavidus Metallidurans Ch34-putative Co-utilization Of Otmentioning

confidence: 99%

Geobiological Cycling of Gold: From Fundamental Process Understanding to Exploration Solutions

et al. 2013

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“…X-ray Absorption Fine Structure (EXAFS) experiments were conducted by Song et al (2012) which place rigorous constraints on the form, valence state, and chemical environment of bacteria-associated Au. Using both X-ray Absorption Near Edge Structure (XANES) and EXAFS measurements of Au bound to biomass, Song et al (2012) found that greater than 90% of the adsorbed Au, which began as Au(III) in solution, was reduced to Au(I) by nonmetabolizing Bacillus subtilis and Pseudomonas putida cells.…”

Section: Introductionmentioning

confidence: 99%

“…Using both X-ray Absorption Near Edge Structure (XANES) and EXAFS measurements of Au bound to biomass, Song et al (2012) found that greater than 90% of the adsorbed Au, which began as Au(III) in solution, was reduced to Au(I) by nonmetabolizing Bacillus subtilis and Pseudomonas putida cells. Song et al (2012) also observed no Au(0) or Au-Au nearest neighbors, indicating that Au(0) nanoparticles were not formed in their experiments. Furthermore, although Au was present in their experiments initially as aqueous Au(III)-chloride species, chloride was not a constituent of the Au-bacterial surface complexes that formed.…”

Section: Introductionmentioning

confidence: 99%

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An experimental study of Au removal from solution by non-metabolizing bacterial cells and their exudates

Kenney

Song

Bunker

et al. 2012

Geochimica et Cosmochimica Acta

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Sulfur Promotion in Au/C Catalyzed Acetylene Hydrochlorination

Dawson

Pattisson

Malta

et al. 2021

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The addition of a second metal has demonstrated various improvements such as stabilizing Au active species by preventing reduction of Au (I) or Au (III), [3][4][5][6][7] increasing electron density of active species, and thereby promoting chemisorption of HCl which inhibits reduction of the gold, [8][9][10][11] promoting a higher dispersion of the gold, [12,13] and decreasing the formation of nanoparticles by agglomeration. [14] However, the addition of another metal can also incur drawbacks such as lower selectivity, which can lead to coke deposition and rapid deactivation of the catalyst, [13] short lifetime of the catalyst, [3,15] or the requirement of high loadings of the second metal to achieve comparable results to the gold monometallic. [5,13,16] In addition to these issues, a secondary metal may also lead to complications with precious metal recovery from spent catalysts. [17,18] Therefore non-metallic promoters are an interesting alternative for enhancing the activity and stability of gold catalysts for acetylene hydrochlorination. Zhang et al. investigated the modification of gold catalysts with nitrogen, phosphorous, and oxygen containing ligands. The authors concluded that coordination with these heteroatoms stabilized cationic gold species due to increased electron density around the active species. This also promoted a higher surface concentration of HCl compared with acetylene which facilities the hydrochlorination The formation of highly active and stable acetylene hydrochlorination catalysts is of great industrial importance. The successful replacement of the highly toxic mercuric chloride catalyst with gold has led to a flurry of research in this area. One key aspect, which led to the commercialization of the gold catalyst is the use of thiosulphate as a stabilizing ligand. This study investigates the use of a range of sulfur containing compounds as promoters for production of highly active Au/C catalysts. Promotion is observed across a range of metal sulfates, non-metal sulfates, and sulfuric acid treatments. This observed enhancement can be optimized by careful consideration of either pre-or post-treatments, concentration of dopants used, and modification of washing steps. Pre-treatment of the carbon support with sulfuric acid (0.76 m) resulted in the most active Au/C in this series with an acetylene conversion of ≈70% at 200 °C.

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An X-ray Absorption Fine Structure study of Au adsorbed onto the non-metabolizing cells of two soil bacterial species

Cited by 40 publications

References 42 publications

Geobiological Cycling of Gold: From Fundamental Process Understanding to Exploration Solutions

Geobiological Cycling of Gold: From Fundamental Process Understanding to Exploration Solutions

An experimental study of Au removal from solution by non-metabolizing bacterial cells and their exudates

Sulfur Promotion in Au/C Catalyzed Acetylene Hydrochlorination

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