PROCESS AND ION-EXCHANGE MATERIALS FOR REMOVAL OF AMMONIA FROM AQUEOUS STREAMS

摘要

1411815 Treating ammoniacal solutions; hydrous oxides BATTELLE DEVELOPMENT CORP 6 Oct 1972 [7 Oct 1971] 46215/72 Headings C1A C1C and ClN [Also in Divisions C7 and C3] Ammonia is removed from an aqueous stream, e.g. an effluent by contacting the stream at a pH of 9-12 with a water-insoluble ionexchange medium containing a firmly-bound metal which forms a stable ammine complex with the ammonia. The metal may be CoII, CoIII, NiII, Cu1, CuII, AgI, ZnII, Cd11 or HgII. The ion exchange medium may be a synthetic resin, which is loaded by contact with metal salt solution, or a hydrous oxide, e.g. of Zr, Ti, Th, Sn, Ta, Cr or Nb, which may be precipitated from a salt solution by means of an ammoniacal solution, e.g. of CuSO 4 or the preformed oxide may be treated with the ammoniacal solution, followed by removal of the bound NH 3 by means of a buffer solution of pH # 8 or of HOCl solution. Regeneration may be effected by contact with an aqueous buffer solution of pH # 8, preferably 4-7, e.g. a buffered alkali metal acid phosphate solution of pH 6À8. The resulting solution may contain NaCl and is then electrolysed to form N 2 ; or it may be treated with H 3 PO 4 or H 2 SO 4 , or with a source of Mg, e.g. MgO to form MgNH 4 PO 4 . Alternatively, acids may be used for regeneration, e.g. H 2 SO 4 , HNO 3 , H 3 PO 4 or HCl, to form the corresponding NH 4 salts. Preferably the ion-exchanger is in the form of a membrane, the ammonia solution being fed to one side and the regenerating stream to the other, continuously. Thus pulverized hydrous TiO 2 or ZrO 2 was mixed with divinylidene fluoride in dimethylacetamide, the mixture spread over a piece of cheesecloth, allowed to dry and submerged in water to complete the polymerization and produce a membrane.