The citric acid–MnIII,IVO2(birnessite) reaction. Electron transfer, complex formation, and autocatalytic feedback

Wang, Yun; Stone, Alan T.

doi:10.1016/j.gca.2006.06.1551

Cited by 77 publications

(72 citation statements)

References 58 publications

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“…The XRD analysis yielded dspacing patterns located at 7.23, 3.66, 2.57 and 1.69 Å. These patterns are consistent with the literature (Wang and Stone, 2006a (Fig. 3).…”

Section: Manganese Dioxide Preparation and Characterizationsupporting

confidence: 90%

“…Perhaps most interesting was that the initial Mn(II) dissolution from the Cu-Citrate 1:0.5 and 1:1 (oxic) solutions followed the ionic Cu(II) curve, in contrast to the s-shaped induction curves of Mn(II) dissolution mediated by citrate found in this study and in Wang and Stone, 2006a. This similarity suggests that Cu-Citrate1:1 (oxic) may form initial ternary surface complexes through the octahedral coordination sphere of the citrate coordinated Cu instead of through the citrate ligand.…”

Section: àcontrasting

confidence: 67%

“…S4). The initial oxidation product is acetonedicarboxylic acid (Wang and Stone, 2006a;Meichtry et al, 2011), as shown in Fig. 2A and B. Acetonedicarboxylate ( Fig.…”

Section: àmentioning

confidence: 93%

“…Manganese hydr(oxides) are powerful oxidants and effective natural cation-exchange sinks, and they can be reduced by organic acid carboxyl or hydroxyl functional groups (Stone and Morgan, 1984). In a study of the citric acid d-MnO 2 reaction, an induction period and s-shaped Mn(II) dissolution curves led to the proposal of a special auto-catalytic Mn(II)-Mn(III)-citrate cycle (Wang and Stone, 2006a). Although some amount of foundational work on the interactions of citrate under different conditions has been laid, questions remain regarding the Cu-Citrate reactions with subsurface (hydr)oxides or other Cu-coordination complexes.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Reaction of aqueous Cu–Citrate with MnO2 birnessite: Characterization of Mn dissolution, oxidation products and surface interactions

Jefferson

Liu

et al. 2015

Chemosphere

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“…The XRD analysis yielded dspacing patterns located at 7.23, 3.66, 2.57 and 1.69 Å. These patterns are consistent with the literature (Wang and Stone, 2006a (Fig. 3).…”

Section: Manganese Dioxide Preparation and Characterizationsupporting

confidence: 90%

Section: àcontrasting

confidence: 67%

“…S4). The initial oxidation product is acetonedicarboxylic acid (Wang and Stone, 2006a;Meichtry et al, 2011), as shown in Fig. 2A and B. Acetonedicarboxylate ( Fig.…”

Section: àmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

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Reaction of aqueous Cu–Citrate with MnO2 birnessite: Characterization of Mn dissolution, oxidation products and surface interactions

Jefferson

Liu

et al. 2015

Chemosphere

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“…Here the trisodium citrate was oxidized by I 3 À to produce disodium 1,3-acetonedicarboxylate (C 5 H 4 Na 2 O 5 ). 8 In addition, Au 0 produced by reduction of Au III ions by citrate was reoxidized by I 3 À . In other words, excess I 3 À could prevent Au III ions from being reduced by trisodium citrate.…”

mentioning

confidence: 99%

Simple and Environmentally Compatible One-pot Synthesis of Au Nanoparticles from Bulk: Separation of Au, Ag, and Cu in Water

Nishida¹,

Ichikawa²,

Toshima³

2009

Chemistry Letters

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Simple and environmentally compatible one-pot synthesis of Au nanoparticles, starting from dissolving bulk Au into mixed aqueous solution of poly(N-vinyl-2-pyrrolidone), potassium iodide, and iodine and ending by isolating Au nanoparticles produced by reducing the dissolved Au ions with sodium citrate, was developed to provide a novel method to separate Au from mixtures of Au, Ag, and Cu.Au nanoparticles have received much attention from the viewpoint of novel properties such as catalyses 1 and optics 2 because they have quite different properties from bulk Au. On the other hand, bulk Au is known to be chemically stable and have excellent electroconductivity. Thus, the noble metal elements of not only Au but also Ag, Cu, Pd, and Pt have been used for various applications, for example, mobile phones, personal computers, and automobile catalysts. Simple and environmentally compatible methods for recovery of noble metals from used electronic equipment are expected to be developed.3 However, much energy and special reagents are required such as strong acid or base to collect or recover noble metal elements because of their chemical stability. Previously, Nakao reported a method to dissolve noble metal elements into a halogen-halide-organic solvent system. [4][5][6][7] This method does not use strong acid, for example aqua regia, but requires the use of an organic solvent like acetonitrile or methanol. In the present study, we would like to report a selective one-pot synthetic method of Au nanoparticles from bulk by dissolving it into an aqueous solution of poly(N-vinyl-2-pyrrolidone) (PVP), potassium iodide, and iodine. This method has several advantages with respect to environmental load because the solvent is only water, no aqua regia is used, and the separation is carried out by ultrafiltration. It is very useful that Au nanoparticles can be obtained directly from discarded electronic products.The schematic chart of synthesis of Au nanoparticles is shown in Scheme 1. PVP (K30, average molecular weight 40000, 630 mg, 5.6 mmol in monomer unit) was put into a 200-mL two-neck flask with deionized water (70 mL), and the mixtures were stirred at room temperature for 10 min. Potassium iodide (93 mg, 0.56 mmol) was added to the mixtures. After 10 min stirring, iodine (70 mg, 0.28 mmol) was added to the mixtures under stirring. After further 10 min stirring, a noble metal wire (Au, Ag, Cu, Pd, or Pt, ¼ 0:2 mm, 0.05 mmol) was added, and the mixtures were heated at 80 C in an oil bath with a reflux condenser and heated for 24 h. Then, trisodium citrate (200 mg, 0.78 mmol) dissolved in deionized water (20 mL) was added to the reaction mixtures, which were stirred for 10 min. Finally 0.1 mmol L À1 sodium hydroxide (10 mL, 1.0 mmol) was added to the mixtures, which were stirred for 20 min.The extent of dissolved metals in solution was determined by measuring weight of wire after the reaction. Within 24 h 100 wt % of Cu and 96.3 wt % of Au were dissolved, but Ag was not. In the case of Ag wire, a weight increase was observed wh...

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Evidence that Crystal Facet Orientation Dictates Oxygen Evolution Intermediates on Rutile Manganese Oxide

Kakizaki

Ooka

Hayashi

et al. 2018

Adv Funct Materials

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Elucidating the mechanism that differentiates the oxygen-evolving center of photosystem II with its inorganic counterpart is crucial to develop efficient catalysts for the oxygen evolution reaction (OER). Previous studies have suggested that the larger overpotential for MnO 2 catalysts under neutral conditions may result from the instability of the Mn 3+ intermediate to charge disproportionation. Here, by monitoring the surface intermediates of electrochemical OER on rutile MnO 2 with different facet orientations, a correlation between the stability of the intermediate species and crystal facets is confirmed explicitly for the first time. The coverage of the Mn 3+ intermediate is found to be 11-fold higher on the metastable (101) surfaces compared to (110) surfaces, leading to the superior OER activity of (101) surfaces. The difference in OER activity may result from the difference in surface electronic states of Mn 3+ , where interlayer charge comproportionation of Mn 2+ and Mn 4+ to generate two Mn 3+ species is favored on (101) facets. Considering the fact that the OER enzyme accommodates Mn 3+ stably during the Kok cycle, the enhanced OER activity of the rutile MnO 2 catalyst with a metastable surface highlights the importance of mimicking not only the crystal structure but also the electronic structure of the targeted natural enzyme.

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The citric acid–MnIII,IVO2(birnessite) reaction. Electron transfer, complex formation, and autocatalytic feedback

Cited by 77 publications

References 58 publications

Reaction of aqueous Cu–Citrate with MnO2 birnessite: Characterization of Mn dissolution, oxidation products and surface interactions

Reaction of aqueous Cu–Citrate with MnO2 birnessite: Characterization of Mn dissolution, oxidation products and surface interactions

Simple and Environmentally Compatible One-pot Synthesis of Au Nanoparticles from Bulk: Separation of Au, Ag, and Cu in Water

Evidence that Crystal Facet Orientation Dictates Oxygen Evolution Intermediates on Rutile Manganese Oxide

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