Silver removal with halogen impregnated activated carbon

• US 4,394,354 A
• Filed: 09/28/1981
• Issued: 07/19/1983
• Est. Priority Date: 09/28/1981
• Status: Expired due to Term

• Current Assignee: Calgon Carbon Corporation (Kuraray Company Limited)
• Original Assignee: Calgon Carbon Corporation (Kuraray Company Limited)
• Inventors: Joyce, Ronald S.
• Primary Examiner(s): Vertiz, O. R.
• Assistant Examiner(s): Stoll, Robert L.
• Application Number:
  US06/305,889
• Time in Patent Office: 659 Days
• Field of Search: 423/25, 75/118 R, 75/118 P, 75/83, 252/415, 252/441, 252/444, 252/447, 210/688, 210/753, 210/501, 210/684
• US Class Current: 423/25
• CPC Class Codes: C01G 5/003 Preparation involving a liquid-liquid extraction, an adsorption or an ion-exchange
• CPC Class Codes: C01G 5/02 Halides
• CPC Class Codes: C22B 3/24 by adsorption on solid substances, e.g. by extraction with solid resins
• CPC Class Codes: G03C 5/3956 Microseparation techniques using membranes, e.g. reverse osmosis, ion exchange, resins, active charcoal G03C5/3954 takes precedence
• CPC Class Codes: Y02P 10/20 Recycling

Abstract

The removal of silver from photographic and other solutions using halogen impregnated activated carbon is described.

Claims

1. A process for removing the anionic silver thiosulfate complex from an aqueous solution comprising contacting said solution with halogen impregnated activated carbon containing at least 0.1 weight percent halogen, said halogen being selected from the group consisting of iodine, bromine or any combination of iodine and bromine.

2. The process of claim 1 wherein the halogen impregnated activated carbon contains from about 5 to 50 weight percent of iodine, bromine, or the combination of iodine and bromine.

3. The process of claim 2 wherein the halogen impregnated activated carbon contains about 10 weight percent of iodine, bromine or the combination of iodine and bromine.

4. The process of claim 3 which further comprises contacting said solution and said impregnated activated carbon up to breakthrough.

5. The process of claim 1 wherein the aqueous silver-thiosulfate complex concentration is less than 500 ppm.

6. The process of claims 1 or 2 or 3 or 4 wherein the halogen is iodine.