Preparation of modified polyacrylamide hydrogels and application in removal of Cu(II) ion

Modified polyacrylamide hydrogels were prepared by transamidation and Hofmann reactions using different amine compounds. Products were characterized by their amine value (AV), equilibrium degree of swelling (EDS) and FT-IR spectroscopy. In case of transamidation on crosslinked polyacrylamide (CPAAm) in aqueous media, AV increased with reaction time and temperature, but EDS decreased with time, especially for reactions at higher temperatures. On the other hand, transamidation reactions on linear polyacrylamide (LPAAm) gave products with higher AV, but quite lower EDS than aqueous media products. Hofmann reactions were carried out on CPAAm with different amounts of NaOCl in the presence of amine compounds, to yield products with higher AV and EDS compared with conventional Hofmann reactions. The products were used for removal of copper (II) ion at pH = 5.5 by batch equilibrium technique. A maximum removal capacity of 2.93 mmol Cu(II)/g was obtained after a regeneration cycle. (C) 2001 Elsevier Science Ltd. All rights reserved.