Nickel (II) Oxide Solubility and Phase Stability in High Temperature Aqueous Solutions.

Ziemniak, S. E. ; Goyette, M. A.

Technical Information Center Oak Ridge Tennessee

关键词: Aqueous solutions;    Nickel oxides;    Solubility;    Phase stability;    High temperature;   

RP-ID  :  DE2005837463

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

A platinum-lined, flowing autoclave facility was used to investigate the solubility behavior of nickel(II) oxide (NiO) in deoxygenated ammonium and sodium hydroxide solutions between 21 and 315 C. Solubilities were found to vary between 0.4 and 400 nmol kg(sup -1). The measured nickel ion solubilities were interpreted via a Ni(II) ion hydroxo-and amino-complexing model and thermodynamic functions for these equilibria were obtained from a least-squares analysis of the data. Two solid phase transformations were observed: at temperatures below 149 C, the activity of Ni(II) ions in aqueous solution was controlled by a hydrous Ni(II) oxide (theophrastite) solid phase rather than anhydrous NiO (bunsenite); above 247 C, Ni(II) activities were controlled by cubic rather than rhombohedral bunsenite.