The precipitation of alkaline-earth metal and transition metal ‘oxinate’ powders from aqueous solution. Crystal numbers and final sizes

✍ Scribed by Dr. A. Packter; P. Chauhan

• Publisher: John Wiley and Sons
• Year: 1975
• Tongue: English
• Weight: 406 KB
• Volume: 10
• Category: Article
• ISSN: 0232-1300
• DOI: 10.1002/crat.19750100911

✦ Synopsis

Abstract

The precipitation of barium strontium, calcium, magnesium, zinc, cadmium and lead, manganese, cobalt, nickel and copper 8‐quinolinolates (‘oxinates’) was studied from equivalent solutions, at __p__Hs from 4.5 to 10, by optical microscopy: the metal cation and overall ‘oxinate’ with ‘oxine’ concentrations were varied from 0.0002 to 0.020 M (while the mean metal oxinate concentrations varied from 10^−7^ to 0.001 M). Crystal growth started after induction periods; the precipitations were heterogeneously nucleated at low supersaturations and homogeneously nucleated at medium to high supersaturations. The final precipitate crystal numbers depended on the number of nuclei formed during the induction periods. Crystal numbers at medium to high supersaturations increased with increasing initial metal oxinate concentration according to the relation,
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The final crystal lengths in this supersaturation range then decreased (from maximum values) with increasing initial mean metal oxinate concentration according to the relation,
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For precipitation from solutions of any concentration at any __p__H, smaller crystals were generally obtained in the precipitates from solutions of the metal oxinate of lower solubility.