Abstract: Process and composition for treating aqueous media to remove impurities using chitosan, polysilicic acid and/or poly aluminosilicate, ferric compound and clay.

Abstract: N-Halochitosans which are terpolymers containing 1 to 35% of 2-deoxy-2-acetaminodoglucose monomeric units, 1 to 90% of 2-deoxy-2-haloaminoglucose monomeric units, and 8-98% of 2-deoxy-2-haloaminoglucose monomeric units wherein the halogen is chlorine or bromine and their preparation is disclosed. The preferred preparation is by treatment of an aqueous solution of a chitosan salt with a halogenating agent.

Abstract: A process for the removal of soluble polyvalent metal impurities from aqueous streams, the polyvalent metal selected from groups IIIA, IIIB, IVA, IVB, VA, VB, VIB, VIIB, and VIII in the periodic table of elements, is disclosed. The process comprises, in order:(1) dissolving (a) chitosan or a water soluble salt thereof and (b) a halogenating agent capable of converting chitosan to an N-halochitosan in an aqueous stream that (i) contains said polyvalent metal impurity as a cationic or complex anionic moiety and (ii) is at a pH of 2 to 5.5, wherein an effective amount of N-halochitosan is formed in said aqueous stream to remove said polyvalent metal impurity;(2) raising the pH of the aqueous stream to a pH greater than 6, the pH being sufficiently high to form an insoluble product containing the polyvalent metal impurity and said N-halochitosan; and(3) separating the insoluble product from the aqueous stream.