Metal ion retention using the ultrafiltration technique: Preparation, characterization of the water-soluble poly(1-vinyl-2-pyrrolidone-co-itaconic acid) and its metal complexes in aqueous solutions

摘要

Radical copolymerization of 1-vinyl-2-pyrrolidone with itaconic acid at different feed monomer ratios (75-25 mol %) were investigated. The copolymers were characterized by elemental analysis, Fourier transform infrared (FTIR), H-1 and C-13 NMR spectroscopy. The copolymer composition was determined from elemental analysis and found to be statistical copolymers. Additionally, viscosimetric measurements, molecular weight, and polydispersity have been determined. The metal complexation of poly(l-vinyl-2-pyrrolidone-co-itaconic acid) for the metal ions such as Cr(III), Co (II), Zn(II), Ni(II), Cu(II), Cd(II), and Fe(Ill) were investigated at pH 3, 5, and 7 in aqueous solution. The metal ion interaction with hydrophilic polymers was determined as a function of the pH and filtration factor. Poly(1-vinyl-2-pyrrolidone-co-itaconic acid) showed a high affinity for the metal ions at pH 5 and 7. The poly(NVP-co-IA), with a copolymer composition of 29 : 71 mol % (PVA-3), presented the highest metal ion retention values, particularly at higher pHs, at which the carboxylic acid groups are nonprotonated and could easily coordinate with the metal ions. According to the interaction pattern obtained, Cr(II), Zn(II), Pb(II), and Ni(II) formed the most stable complexes at pH 7. The thermal behaviors of the copolymer and polymer metal complex were characterized using differential scanning calorimetry (DSC) and thermogravimetry techniques under nitrogen atmosphere. The copolymers present high thermal stability and do not present glass transition in DSC curves between 25 and 500 degrees C. (C) 2008 Wiley Periodicals, Inc.