Method for removing trace pollutants from aqueous solutions

• US 4,572,797 A
• Filed: 03/02/1983
• Issued: 02/25/1986
• Est. Priority Date: 03/02/1983
• Status: Expired due to Fees

• Current Assignee: United States Department Of Health And Human Services (Government of the United States of America)
• Original Assignee: United States Department of Energy (Government of the United States of America)
• Inventors: Silver, Gary L.
• Primary Examiner(s): Lechert, Jr., Stephen J.
• Assistant Examiner(s): Locker, Howard J.
• Application Number:
  US06/471,566
• Time in Patent Office: 1,091 Days
• Field of Search: 252/631, 252/626, 252/627, 252/632, 210/717, 210/721, 210/722, 210/724, 210/737, 210/682, 423/2, 423/11, 423/12, 423/55, 423/142, 423/92, 423/140, 423/158, 423/160
• US Class Current: 588/18
• CPC Class Codes: C02F 1/72 by oxidation C02F1/4672 takes precedence
• CPC Class Codes: C02F 2101/20 Heavy metals or heavy metal compounds
• CPC Class Codes: G21F 9/06 Processing separating different isotopes of the same chemical element B01D59/00

Abstract

A method of substantially removing a trace metallic contaminant from a liquid containing the same comprises,

adding an oxidizing agent to a liquid containing a trace amount of a metallic contaminant of a concentration of up to about 10^-1 ppm, the oxidizing agent being one which oxidizes the contaminant to form an oxidized product which is insoluble in the liquid and precipitates therefrom, and the conditions of the addition being selected to ensure that the precipitation of the oxidized product is homogeneous, and

separating the homogeneously precipitated product from the liquid.

Claims

1. A method of substantially removing a trace metallic contaminant from a liquid containing the same, consisting of:

continuously adding an oxidizing agent to a liquid containing up to 10^-2 ppm of the contaminant to form an oxidized product which precipitates therefrom, with the conditions of the addition being selected to ensure that the precipitation of the oxidized product is homogeneous; and

continuously separating the homogeneous precipitated product from the liquid by allowing said precipitate to crystallize on the walls of a cylindrical container in which the method is carried out;

said contaminant being cobalt, nickel, manganese, thallium, iron (II), platinum, iridium, antimony, strontium, osmium, lead, tin, uranium, or plutonium; and

said oxidizing agent being an alkali or alkaline earth metal hypochlorite or a combination of an alkali or alkaline earth metal sulfite and O₂.

2. The method of claim 1 wherein the contaminant is a radioactive metal.

3. The method of claim 2 wherein the contaminant is radioactive cobalt.

4. The method of claim 1 wherein the oxidixing agent is a combination of calcium sulfite or sodium sulfite and O₂ and the pH of the liquid is about 5-13.

5. The method of claim 4 wherein the oxidizing agent is a combination of calcium sulfite, a liquid-soluble soluble Ni²⁺ salt and O₂.

6. The method of claim 4 wherein the oxidizing agent is sodium hypochlorite and the pH of the liquid is about 3-13.

7. The method of claim 1 wherein the contaminant is radioactive cobalt and wherein non-radioactive cobalt is added prior to oxidation and precipitation to raise the total cobalt concentration to about 1000 ppm.