REMOVAL OF CU(II) FROM AQUEOUS-SOLUTION WITH HIGH IONIC-STRENGTH BY ADSORBING COLLOID FLOTATION

Copper ion was removed from wastewater by adsorbing colloid flotation with iron(III) hydroxide and sodium dodecyl sulfate (SDS) at optimum pH (7.5-8.5) provided that the ionic strength of the solution was small (containing no greater than 0.03 M Na2SO4 or 0.5 M NaNO3). The electrolyte tolerance of adsorbing colloid flotation of Cu(II) is improved with the aid of activators, such as Mg(II) or Ca(II) ions. Effective separation was achieved over a greater range of pH (7.5-10.0) from wastewater with much greater ionic strength (0.8 M Na2SO4 or 1.6 M NaNO3) when a mixture of SDS and sodium oleate is used as the frother and collector, in contrast to that using SDS alone. The applicability of an adsorbing colloid flotation technique to remove heavy metals from wastewater is thus greatly extended. As the separation efficiency is insensitive to the variation of pH and ionic strength, the flotation process operates much more easily with a mixture of SDS and oleate as the frother and collector.