N, N’-Methylene-bis-acrylamide- Crosslinked Polyacrylamides as Supports for Dithiocarbamate Ligands for Metal Ion Complexation

The complexation behaviour of dithiocarbamate functions supported on polyacrylamides with varying extents (2-20 mol YO) of 4”-methylene-bisacrylamide (NNMBA) crosslinks was investigated. The crosslinked polyacrylamides were prepared by the free radical solution polymerization of the mononicrs in water at 80°C using potassium persulphate as initiator. The dithiocarbamate ligands were introduced by polymer-analogous reaction involving transamidation with ethylenediamine and dithiocarbamylation with carbon disulphide and alkali. The complexation behaviour of these dithiocarbamate resins with the ligand functions in different macromolecular environments were investigated towards Co(lI), Ni(Il), Cu(lI), Zn(I1) and Hg(l1) ions by a batch equilibration technique. The metal ion intake varied with the extent of the NNMBA-crosslinking. Thus the 8 % crosslinked system has the highest complexation capacity. The values for metal ion intake followed the order Hg(I1) >> Cu(1I) > Zn(1I) > Ni(l1) > Co(1I). Thc timccourse of complexation, the possibility of recycling and the swelling characteristics of the uncomplexed and complexed resins were considered, and I R characterization and thermal studies were undertaken. The swelling values of the complexed resins are lower than those of the uncomplexed resins. The thermal stability of dithiocarbamates varied with the extent of NNMBA-crosslinks and with the metal ion. Key iwrdss: polymer-metal complexes, crosslinked polyacrylamide-support, dithiocarbarnate-metal complexes, thermal stability.