Model cationic flocculants from the Mannich reaction of polyacrylamide

Abstract 14 C‐Labeled cationic derivatives of polyacrylamide were prepared by the reaction of polyacrylamide with 14 C‐labeled formaldehyde and dimethylamine hydrochloride. The resulting Mannich base was reacted with dimethyl sulfate. Both reactions produced a yield of about 50% and the final product was a substituted polyacrylamide with tertiary and quaternary amine groups. Extensive dialysis removed the tertiary groups to give a stable radio‐labeled polymer that was an effective flocculant. Treatment with mixed‐bed ion exchange resin was effective in purifying polyacrylamide derivatives; however, counterions for the quanternary amine groups were not quantitatively exchanged for hydroxide groups.