Flotation of organic reagent precipitates

HIRAIDE Masataka, MIZUIKE Atsushi

doi:10.2116/bunsekikagaku.26.10_655

The collection of trace elements on organic reagent precipitates from aqueous solutions offers a useful separation technique in trace analysis, but difficulties sometimes arise in filtering off the bulky amorphous precipitates from the mother liquor. Centrifugation is often not applicable because of incomplete sedimentation. Previously, the authors have proposed a simple and rapid flotation technique to overcome these difficulties. The present paper describes the flotation step in detail. An acetone solution of organic reagent {(0.550)mg/ml}, 5 ml, was added to 200 ml of diluted nitric acid, which was then stirred for 15 min to coagulate the precipitates. Nitrogen was passed through a sintered-glass disc (porosity-4) into the solution containing the precipitates for about 30 s. The precipitates were readily floated by the capture of small bubbles (below 0.5 mm diam.) in the interstices and on the surfaces of the precipitates, and a stable precipitate layer containing numerous bubbles was formed on the solution surface. The precipitates were hydrophobic. For the successful flotation, however, it was also necessary to coagulate the precipitates larger than bubble diameters by the stirring. Surfactants were not added, because the removal of the resulting stable numerous bubbles from the precipitates was difficult.

Flotation of organic reagent precipitates

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