A study of adsorptive bubble separation methods for removal of metal ions from aqueous solution

Abstract

A study has been made of the removal of the copper (II) ions from aqueous solution by dispersed-air flotation, dissolved-air
flotation and liquid-liquid extraction techniques. Precipitation of the copper (II) species has been achieved by complexing
with a long-chain a-dioxime, 5,6-decandionedioxime, which was synthesised and characterised by spectroscopic and analytical techniques.
The effects of-variables, including recycle volume and solution pH, on the removal by flotation of copper (II) in the presence of the dioxime have been studied and the results discussed in terms of the flotation process. It has been found in general that flotation was complete within two minutes and redispersion tended to occur with extended flotation times. The flotation process produced-good removal of copper (It) ions (395%) from solutions with pH >6.0.
Liquid-liquid extraction studies were carried out using the dioxime dissolved in octan-l-ol and the •results obtained have been used to compare liquid-liquid extraction and flotation processes and to obtain information concerning the nature of the extracted species.
The extraction of copper (II) was studied as a function of pH and of varying copper (II):oxime ratio. The results were analysed
in terms of the general extraction equation: rnHA "'n/x (HxA)(mn)/x + nHx and it was established chat under the extraction conditions studied n = 2 and (mix) 2.
The non-aqueous phasein the liquid-liquid extraction system studied was varied in order to investigate the effect on the extraction of copper (II), and the copper (II) concentration was varied at a constant oxime concentration to determine whether there was evidence of polymerisation in the extracted species.
The results obtained indicated the existence of such polymerisation but it was not possible to establish unequivocally the actual degree of polymerisation from the graphical methods of analysis used.