GB1260186A - Recovering constituents of photographic colour development solutions - Google Patents

Abstract

1,260,186. Recovery of aromatic amines from developers. EASTMAN KODAK CO. 25 March, 1969 [27 March, 1968], No. 15419/69. Heading C2C. [Also in Division G2] Primary aromatic amino developing agents, particularly those of general formula wherein R and R 1 each represents hydrogen, a C 1 -C 6 alkyl group, which may be substituted (e.g. by hydroxy, amino, acetamido, or methylsulphonamido), a C 1 -C 6 alkoxy group, hydroxy or halogen, and R 2 and R 3 each represents a substituted or unsubstituted alkyl group, are recovered from a photographic colour developing solution by adding to the solution, the pH of which is (adjusted if necessary) between 9 and 14, a water soluble inorganic salt, having a water solubility of at least 30 g./l., in sufficient amount to result in the formation of a second phase, and thereafter separating the second phase, which consists essentially of the developing agent as the free base. Colour couplers that are also present in the photographic solution may be removed prior to the salt treatment by precipitation using mineral acid and carbon dioxide. Alternatively, the pH of the solution is adjusted to between 9À0 and 10À5 and the watersoluble salt added when the second phase is found to contain both colour developing agent and coupler. Benzyl alcohol, when present, can also be removed in the second phase if the process is operated at pH between 9 and 11. Specified water-soluble salts include sodium sulphate and other alkali metal and ammonium salts, e.g. bisulphate, sulphite, carbonate, bicarbonate and chloride. The salt content is between 60 and 500 g./l., preferably from 125-250 g./l. The process may be operated continuously or intermittently and the recovered materials can be recycled to the colour processing bath.