Gold-leaching performance and mechanism of sodium dicyanamide

Li, Gen-zhuang; Kou, Jue; Xing, Yi; Hu, Yang; Han, Wei; Liu, Zi-yuan; Sun, Chunbao

doi:10.1007/s12613-020-2153-6

Cited by 10 publications

(2 citation statements)

References 19 publications

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“…This hinders the formation of a passivating oxide layer, which lowers the dissolution in the absence of the IL . Second, it is known that dicyanamide forms complexes with different metals, such as Cr, Mn, Fe, Co, Ni, and Cu and Au. − For Au, Li et al found during gold leaching in the presence of sodium dicyanamide (NaN(CN) 2 ) various gold complexes ([AuNa x (N(CN) 2 ) x +2 ] − ( x = 1, 2, 3, 4)) in solution. Such complexes stabilize the Au ions against redeposition on the surface, resulting in an increase of the Au signal in the online ICP-MS measurements in the presence of the IL.…”

Section: Results and Discussionmentioning

confidence: 99%

Interactions of the Ionic Liquid [C₂C₁Im][DCA] with Au(111) Electrodes: Interplay between Ion Adsorption, Electrode Structure, and Stability

Yang,

Hilpert,

Qiu

et al. 2024

J. Phys. Chem. C

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Modification of electrocatalysts with ionic liquids (ILs) allows us to control the activity and selectivity on the one hand but also directly affects the stability of the electrode. In this work, we studied the interaction of the IL 1-ethyl-3-methylimidazolium dicyanamide [C 2 C 1 Im][DCA] with a Au(111) surface in an aqueous electrolyte (phosphate buffer, pH 7) and the impact of the IL on the electrochemical stability of the surface. We combined complementary electrochemical in situ methods, namely, electrochemical infrared reflection absorption spectroscopy (EC-IRRAS), cyclic voltammetry (CV), electrochemical scanning tunneling microscopy (EC-STM), and online inductively coupled plasma mass spectrometry. We observe the potential-dependent and reversible adsorption−desorption of ionic species on the Au(111) surface in the potential window between 0.1 and 1.1 V RHE . We identified two types of adsorbed [DCA] − species, showing different adsorption kinetics. Already at low concentrations, the IL (10 mM) enhances the dissolution during oxidation and reduction cycles by a factor of more than 40. We observe a suppressed redeposition of dissolved Au-ions in the presence of the IL due to the formation of gold complexes with the [DCA] − anions. Our result provides molecular insights into the interplay between ionic liquid−surface interactions and surface stability.

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Section: Results and Discussionmentioning

confidence: 99%

Interactions of the Ionic Liquid [C₂C₁Im][DCA] with Au(111) Electrodes: Interplay between Ion Adsorption, Electrode Structure, and Stability

Yang,

Hilpert,

Qiu

et al. 2024

J. Phys. Chem. C

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“…In addition to the alternative lixiviants mentioned above, new highly efficient and environmentally friendly reagents have been discovered or designed, such as ionic liquid, dicyanamide, ferrocyanide, etc. [ 22 , 23 , 24 ]. However, those new gold leaching reagents are in the preliminary research phase.…”

Section: Introductionmentioning

confidence: 99%

Investigation on Gold–Ligand Interaction for Complexes from Gold Leaching: A DFT Study

2023

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Gold leaching is an important process to extract gold from ore. Conventional alkaline cyanide process and alternative nontoxic lixiviants including thiosulfate, thiourea, thiocyanate, and halogen have been widely investigated. However, density functional theory (DFT) study on the gold complexes Au(CN)2−, Au(S2O3)23−, Au[SC(NH2)2]2+, Au(SCN)2−, and AuCl2− required for discovering and designing new highly efficient and environmentally friendly gold leaching reagents is lacking, which is expected to support constructive information for the discovery and designation of new high-efficiency and environmentally friendly gold leaching reagents. In this study, the structure information, electron-transferring properties, orbital interaction, and chemical bond composition for complexes Au(CN)2−, Au(S2O3)23−, Au[SC(NH2)2]2+, Au(SCN)2−, and AuCl2− depending on charge decomposition analysis (CDA), natural bond orbital (NBO), natural resonance theory (NRT), electron localization function (ELF), and energy decomposition analysis (EDA) were performed based on DFT calculation. The results indicate that there is not only σ-donation from ligand to Au+, but also electron backdonation from Au+ to ligands, which strengthens the coordinate bond between them. Compared with Cl−, ligands CN−, S2O32−, SC(NH2)2, and SCN− have very large covalent contribution to the coordinate bond with Au+, which explains the special stability of Au-CN and Au-S bonds. The degree of covalency and bond energy in Au–ligand bonding decreases from Au(CN)2−, Au(S2O3)23−, Au[SC(NH2)2]2+, Au(SCN)2−, to AuCl2−, which interprets the stability of the five complexes: Au(CN)2− > Au(S2O3)23− > Au[SC(NH2)2]2+ > Au(SCN)2− > AuCl2−.

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Selective gold extraction from electronic waste using high-temperature-synthesized reagents

Li,

Sun,

Wang

et al. 2023

Environ Sci Pollut Res

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Gold-leaching performance and mechanism of sodium dicyanamide

Cited by 10 publications

References 19 publications

Interactions of the Ionic Liquid [C₂C₁Im][DCA] with Au(111) Electrodes: Interplay between Ion Adsorption, Electrode Structure, and Stability

Interactions of the Ionic Liquid [C₂C₁Im][DCA] with Au(111) Electrodes: Interplay between Ion Adsorption, Electrode Structure, and Stability

Investigation on Gold–Ligand Interaction for Complexes from Gold Leaching: A DFT Study

Selective gold extraction from electronic waste using high-temperature-synthesized reagents

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Gold-leaching performance and mechanism of sodium dicyanamide

Cited by 10 publications

References 19 publications

Interactions of the Ionic Liquid [C2C1Im][DCA] with Au(111) Electrodes: Interplay between Ion Adsorption, Electrode Structure, and Stability

Interactions of the Ionic Liquid [C2C1Im][DCA] with Au(111) Electrodes: Interplay between Ion Adsorption, Electrode Structure, and Stability

Investigation on Gold–Ligand Interaction for Complexes from Gold Leaching: A DFT Study

Selective gold extraction from electronic waste using high-temperature-synthesized reagents

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Product

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Interactions of the Ionic Liquid [C₂C₁Im][DCA] with Au(111) Electrodes: Interplay between Ion Adsorption, Electrode Structure, and Stability

Interactions of the Ionic Liquid [C₂C₁Im][DCA] with Au(111) Electrodes: Interplay between Ion Adsorption, Electrode Structure, and Stability