Method for selectively capturing metal ions

Claim 1

The method of eliminating at least one kind of metal ions selected from the group consisting of the following metals having the respective characteristic complexing pH ranges ______________________________________ cadmium (Cd.sup.2.sup.+) around 10 - around 12 mercury (Hg.sub.2.sup.2.sup.+) around 7 - around 12 iron (Fe.sup.2.sup.+) around 7 - around 12 chromium (Cr.sup.3.sup.+) around 8 - around 12 copper (Cu.sup.2.sup.+) around 6 - around 12 nickel (Ni.sup.2.sup.+) around 7 - around 12 lead (Pb.sup.2.sup.+) around 8 - around 12 cobalt (Co.sup.2.sup.+) around 9 - around 12 zinc (Zn.sup.2.sup.+) around 10 - around 12 manganese (Mn.sup.2.sup.+) around 10 - around 12 ______________________________________ from a solution containing at least said one kind of metal ions in solution by the steps comprising complexing said ions by adding to said solution an effective amount for complexing with said metal ions of a condensation product of a fatty acid having at least about 8 carbon atoms or an ester or halide thereof with an excess molar amount of a polyamine having the general formula: ##STR2## where R.sub.4-7 each represent a hydrogen atom or a hydrophobic group selected from an alkyl group, and an arylalkyl group, and x is an integer from 1 to 5 and y is an integer from 1 to 4, adjusting the pH of the resultant complex-containing solution to a value within the above-specified characteristic range for the kind of metal ions to be separated, subjecting the pH adjusted solution containing said complex to foaming conditions, and separating from the solution the resultant foam containing the complex of said ions and said condensation product.

Claim 2

The method of eliminating at least one kind of metal ions selected from the group consisting of the following metals having the respective characteristic complexing pH ranges ______________________________________ cadmium (Cd.sup.2.sup.+) around 10 - around 12 mercury (Hg.sub.2.sup.2.sup.+) around 7 - around 12 iron (Fe.sup.2.sup.+) around 7 - around 12 chromium (Cr.sup.3.sup.+) around 8 - around 12 copper (Cu.sup.2.sup.+) around 6 - around 12 nickel (Ni.sup.2.sup.+) around 7 - around 12 lead (Pb.sup.2.sup.+) around 8 - around 12 cobalt (Co.sup.2.sup.+) around 9 - around 12 zinc (Zn.sup.2.sup.+) around 10 - around 12 manganese (Mn.sup.2.sup.+) around 10 - around 12 ______________________________________ from a solution containing at least said one kind of metal ions in solution by the steps comprising complexing said ions by adding to said solution an effective amount for complexing with said metal ions of a condensation product of a fatty acid having at least about 8 carbon atoms or an ester or halide thereof with an excess molar amount of a polyamine having the general formula: ##STR2## where R.sub.4-7 each represent a hydrogen atom or a hydrophobic group selected from an alkyl group, and an arylalkyl group, and x is an integer from 1 to 5 and y is an integer from 1 to 4, adjusting the pH of the resultant complex-containing solution to a value within the above-specified characteristic range for the kind of metal ions to be separated, subjecting the pH adjusted solution containing said complex to foaming conditions, and separating from the solution the resultant foam containing the complex of said ions and said condensation product.