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Title: Method for the recovery of silver from waste photographic fixer solutions

Abstract

The method of the present invention is directed to the recovery of silver from spent photographic fixer solutions and for providing an effluent essentially silver-free that is suitable for discharge into commercial sewage systems. The present method involves the steps of introducing the spent photographic fixer solution into an alkaline hypochlorite solution. The oxidizing conditions of the alkaline hypochlorite solution are maintained during the addition of the fixer solution so that the silver ion complexing agents of thiosulfate and sulfite ions are effectively destroyed. Hydrazine monohydrate is then added to the oxidizing solution to form a reducing solution to effect the formation of a precipitate of silver which can be readily removed by filtration or decanting. Experimental tests indicate that greater than 99.99% of the original silver in the spent photographic fixer can be efficiently removed by practicing the present method. Also, the chemical and biological oxygen demand of the remaining effluent is significantly reduced so as to permit the discharge thereof into sewage systems at levels in compliance with federal and state environmental standards.

Inventors:
 [1];  [2]
  1. (Concord, TN)
  2. (Oak Ridge, TN)
Publication Date:
Research Org.:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN
OSTI Identifier:
864979
Patent Number(s):
US 4445935
Assignee:
United States of America as represented by United States (Washington, DC) ORNL
DOE Contract Number:  
W-7405-ENG-26
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
method; recovery; silver; waste; photographic; fixer; solutions; directed; spent; providing; effluent; essentially; silver-free; suitable; discharge; commercial; sewage; systems; involves; steps; introducing; solution; alkaline; hypochlorite; oxidizing; conditions; maintained; addition; complexing; agents; thiosulfate; sulfite; effectively; destroyed; hydrazine; monohydrate; added; form; reducing; effect; formation; precipitate; readily; removed; filtration; decanting; experimental; tests; indicate; 99; original; efficiently; practicing; chemical; biological; oxygen; demand; remaining; significantly; reduced; permit; levels; compliance; federal; environmental; standards; oxidizing conditions; significantly reduce; complexing agents; method involves; complexing agent; significantly reduced; readily removed; oxygen demand; experimental tests; photographic fixer; method involve; oxidizing solution; hypochlorite solution; fixer solution; fixer solutions; /75/423/

Citation Formats

Posey, Franz A., and Palko, Aloysius A. Method for the recovery of silver from waste photographic fixer solutions. United States: N. p., 1984. Web.
Posey, Franz A., & Palko, Aloysius A. Method for the recovery of silver from waste photographic fixer solutions. United States.
Posey, Franz A., and Palko, Aloysius A. Sun . "Method for the recovery of silver from waste photographic fixer solutions". United States. https://www.osti.gov/servlets/purl/864979.
@article{osti_864979,
title = {Method for the recovery of silver from waste photographic fixer solutions},
author = {Posey, Franz A. and Palko, Aloysius A.},
abstractNote = {The method of the present invention is directed to the recovery of silver from spent photographic fixer solutions and for providing an effluent essentially silver-free that is suitable for discharge into commercial sewage systems. The present method involves the steps of introducing the spent photographic fixer solution into an alkaline hypochlorite solution. The oxidizing conditions of the alkaline hypochlorite solution are maintained during the addition of the fixer solution so that the silver ion complexing agents of thiosulfate and sulfite ions are effectively destroyed. Hydrazine monohydrate is then added to the oxidizing solution to form a reducing solution to effect the formation of a precipitate of silver which can be readily removed by filtration or decanting. Experimental tests indicate that greater than 99.99% of the original silver in the spent photographic fixer can be efficiently removed by practicing the present method. Also, the chemical and biological oxygen demand of the remaining effluent is significantly reduced so as to permit the discharge thereof into sewage systems at levels in compliance with federal and state environmental standards.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1984},
month = {1}
}

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