Direct Observation of Pure Cu and Cu-Ag Anode Passivation in H{sub 2}SO{sub 4}-CuSO{sub 4} Aqueous Solution by Channel Flow Double Electrode and Optical Microscopy

Journal Article · Fri Feb 15 04:00:00 EST 2019 · Metallurgical and Materials Transactions. B, Process Metallurgy and Materials Processing Science

DOI:https://doi.org/10.1007/S11663-018-1447-9· OSTI ID:22933600

Ninomiya, Yuma; Sasaki, Hideaki; Yoshikawa, Takeshi; Maeda, Masafumi ^[1]

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1. The University of Tokyo, Institute of Industrial Science (Japan)

The dissolution and passivation of pure Cu and Cu-5 wt pct Ag anodes in H{sub 2}SO{sub 4}-CuSO{sub 4} electrolyte were investigated by a direct observation method that combined the techniques of optical microscopy and channel flow double electrode. Linear sweep voltammetry of the anodes showed that the dissolution of Cu transited from the charge transfer-controlled reaction to the mass transfer-controlled reaction, followed by the passivation of the electrodes. The direct observation of the pure Cu anode revealed that Cu particles were generated on the surface and the particles fell away during passivation. On the other hand, a slime layer of Ag particles that adhered to the surface was generated during the dissolution of the Cu-5 wt pct Ag anode. The Cu-5 wt pct Ag anode was passivated with a lower current density than the pure Cu anode, which suggested that the morphology and adhesive characteristics of the slime on the anode affected the passivation. The direct observation method described herein is useful for understanding reactions on electrodes that undergo drastic changes in their surface morphology. Information obtained from this method can help with the development of new processes for the effective utilization of limited natural resources and energy, such as the recycling of Cu by electrorefining.

• OSTI ID: 22933600
• Journal Information: Metallurgical and Materials Transactions. B, Process Metallurgy and Materials Processing Science, Journal Name: Metallurgical and Materials Transactions. B, Process Metallurgy and Materials Processing Science Journal Issue: 1 Vol. 50; ISSN 1073-5615; ISSN MTBSEO
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANODES
AQUEOUS SOLUTIONS
COPPER
COPPER SULFATES
CURRENT DENSITY
DISSOLUTION
ELECTROLYTES
ELECTROREFINING
MASS TRANSFER
MORPHOLOGY
OPTICAL MICROSCOPY
PASSIVATION
RECYCLING
SULFURIC ACID
VOLTAMETRY