Compositions for removing lead from metal surfaces
AssigneeStone Chemical Company
InventorsDavid Hunt, George Kuhlmann
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Abstract
The invention provides an aqueous composition that includes a hydroxy-substituted mono-, di-, or tri-carboxylic acid; phosphoric acid; a surfactant; and water. The invention further provides a method for removing lead from the surface of metal, the method includes contacting a metal surface with an aqueous composition that includes a hydroxy-substituted mono-, di-, or tri-carboxylic acid; phosphoric acid; a surfactant; and water; to provide a metal surface with a reduced amount of leachable lead. The leachable lead on the surface of the metal can be reduced to below 1 ppb by using the composition described herein.
Claims21
A metal treating composition for removing lead from a brass surface and passivating the surface, wherein the metal treating composition is a nitric acid-free and perfume-free composition comprising:
- a) about 0.01 wt. % to about 12 wt. % of a hydroxy-substituted mono-, di-, or tri-carboxylic acid;
- b) about 0.01 wt. % to about 10 wt. % phosphoric acid;
- c) about 0.01 wt. % to about 10 wt. % of one or more surfactants, wherein at least one surfactant is an ethoxylated aryl surfactant;
- and
- d) about 70 wt. % to about 99.7 wt. % water.
A metal treating composition for removing lead from a metal surface and passivating the surface, the composition consisting essentially of:
- a) a hydroxy-substituted mono-, di-, or tri-carboxylic acid;
- b) phosphoric acid;
- c) an ethoxylated aryl non-ionic surfactant;
- and
- d) water.
A metal treating composition for removing lead from a metal surface and passivating the surface, wherein the metal treating composition is a nitric acid-free and polymer-free composition consisting of:
- a) a hydroxy-substituted mono-, di-, or tri-carboxylic acid;
- b) phosphoric acid;
- c) an ethoxylated aryl non-ionic surfactant of formula I:
- wherein m is 0 to 3;
- n is about 6 to about 12;
- and
- R is a straight, branched, or cyclic (C1-C12)alkyl group;
- and
- d) water.
Dependencies are inferred from the claim text.