Liquid purification or separation – Processes – Ion exchange or selective sorption
Reexamination Certificate
2002-02-11
2003-04-29
Barry, Chester T. (Department: 1724)
Liquid purification or separation
Processes
Ion exchange or selective sorption
Reexamination Certificate
active
06555008
ABSTRACT:
FIELD OF THE INVENTION
This invention concerns a method for the removal of silver contained in an used photographic silver halide developer.
BACKGROUND OF THE INVENTION
In the photographic industry silver halide films (and papers) are processed after exposure in several treatment baths, in particular at least one developing bath. Such processing methods are well known (see for example Chimie et Physique Photographiques, P. Glafkidès, Vol Chapter XL pages 947-967, 5
th
edition, 1987). One known problem met in the development of silver halide photographic films is the accumulation metallic silver in the forme of silver-laden slurries in the developing bath. This accumulation of silver-laden slurries results in silver deposits adhering to tank walls, conveyor rollers and all the parts of the processing line. These silver deposits require more frequent maintenance and cleaning operations. Also, the presence of silver-laden slurries in the developing bath reduces the useful life of the developer. Lastly, the silver-laden slurries can be deposited on the processed film, where they form black spots or fogging, which may spoil the developed image.
It is therefore desirable to be able to extract these silver-laden slurries and recover the silver in them. Silver recovery may be economically worthwhile, and is becoming mandatory with the increasingly strict current standards for effluent disposal.
SUMMARY OF THE INVENTION
The object of this invention is therefore a method to extract the metallic silver contained in a developer for photographic silver halides, comprising the step of placing the developer in contact with an aluminosilicate polymer having surface organic radicals with functions, selected in the class consisting of SH and —S(CH
2
)
n
S— functions, where n is an integer from 1 to 4 inclusive.
A further object of this invention is a product to extract silver from a photographic developer, comprising (i) an aluminosilicate polymer bearing organic radicals on its surface with functions, selected in the class of SH and —S(CH
2
)
n
S— functions where n is a integer from 1 to 4 inclusive, and (ii) a complexing agent that is released into the photographic developer.
REFERENCES:
patent: 4508838 (1985-04-01), Buckl
patent: 5792793 (1998-08-01), Oda et al.
patent: 0 789 271 (1997-08-01), None
patent: 0 937 393 (1999-08-01), None
JP 62115447—Abstract.
Pine et al., Organic Chemistry, 4th ed., McGraw-Hill Book Company, 1980, p.28, defining “functional groups.”.
Poncelet Olivier J.
Roussilhe Jacques
Wettling Danielle M.
Barry Chester T.
Eastman Kodak Company
Konkol Chris P.
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