Methods of removing silver
AssigneeFuji Photo Film Co., Ltd.
InventorsTakashi Nakamura, Yasuhiro Nakayama, Haruhiko Iwano, Hideo Miyazaki
Life of this patent
Estimating the term…
Abstract
A method of removing silver from a solution containing silver halide and silver ion is described, which comprises a step of adding an a sulfur atom-containing hydrophilic polymer chelating agent to the solution.
Claims11
A method of removing silver, comprising adding, into a solution which is generated in the step of producing a photosensitive material and contains silver halide and silver ion, a water-soluble sulfur atom-containing hydrophilic polymer chelating agent wherein said chelating agent is represented by the general formula I, ##STR4## wherein one of the substituents X and X.sub.1 is --SM, --NHCOSM, --NHCS.sub.2 M or --CH.sub.2 NHCS.sub.2 M, and the other is H;
- M is Li, Na, K or H;
- 0.ltoreq.n.ltoreq.30,000;
- 0.ltoreq.m.ltoreq.30,000;
- and n+m>100 and wherein said chelating agent has a molecular weight in a range of from 50,000 to 500,000 and containing at least one group selected from the group consisting of a dithiocarbamate group, a dithiocarbaminic acid group, and a thiol group.
A method of removing silver, comprising a step of feeding a solution containing silver halide and silver ion into an activated sludge tank and a step of adding a sulfur atom-containing hydrophilic polymer chelating agent, during or subsequently to the treatment with the activated sludge, said sulfur atom-containing hydrophilic polymer chelating agent being a water-soluble sulfur atom-containing hydrophilic polymer chelating agent which contains at least one group selected from among a dithiocarbamate group, a thiocarboxyl group, a dithiocarboxyl group, a dithiocarbaminic acid group and a thiol group.
A method of removing silver as described in the claim 6, wherein the solution containing silver halide and silver ion is fed into the activated sludge tank and an inorganic precipitant and/or an organic polymer precipitant is added before or during the treatment with activated sludge.
A method of removing silver, comprising a step of feeding a solution containing silver halide and silver ion into an activated sludge tank and a step of passing the solution through a single membrane MF filter during or continuously to the treatment with activated sludge.
A method of removing silver from a quantity of waste solution, comprising a step of adding a sulfur atom-containing hydrophilic polymer chelating agent to a solution containing silver halide and silver ion to precipitate and separate out silver, treating the resulting solution with activated sludge and then filtering through a single membrane MF filter under a low pressure of 1 Kg/cm.sup.2 or less, said sulfur atom-containing hydrophilic polymer chelating agent being a water-soluble sulfur atom-containing hydrophilic polymer chelating agent which contains at least one group selected from among a dithiocarbamate group, a thiocarboxyl group, a dithiocarboxyl group, a dithiocarbaminic acid group and a thiol group.
Dependencies are inferred from the claim text.