Metal ion retention from aqueous solution using the ultrafiltration technique: preparation, retention capacity of copolymers of N-maleimide derivatives with beta-methylhydrogen itaconate and metal complexes
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Chlorophenylmaleimide (Cl-PhMI) and N-maleoylglycine (N-MG) with beta-methylhydrogen itaconate (beta-MHI) were copolymerized by radical polymerization, and their metal ion retention capacity (MRC) and thermal behavior were studied. The copolymers were obtained by varying the mole fraction of Cl-PhMI or N-MG in the feed from 0.25 to 0.75. The monomer reactivity ratios, r(1), and r(2), were determined using the Kelen-Tudos method. The molecular weight and polydispersity were also determined. The capacity to remove several metal ions, such as Cu(II), Cr(III), Co(II), Zn(II), Ni(II), Pb(II), and Fe(III), in aqueous phase was determined using the liquid-phase polymer-based retention technique. Inorganic ion interactions with the hydrophilic polymer were determined as a function of pH and the filtration factor. The MRC depends strongly on the pH. Metal ion retention increased with increases in pH and the content of beta-MHI units in the macromolecular backbone. The copolymers and polymer-metal complexes of transition metal ions were characterized using elemental analysis, Fourier transform infrared spectroscopy, H-1 NMR, and electron paramagnetic resonance spectroscopy. The maximum MRC of Cu(II) ions of poly(Cl-PhMI-co-beta-MHI) varied from 240 to 260 mg g(-1), while the MRC of Cu(II) ions of poly(N-MG-co-P MHI) varied from 270 to 318 mg g(-1) at pH 5 and pH 7. The thermal behavior of the copolymers and polymer-metal complexes was studied using differential scanning calorimetry and thermogravimetry techniques under nitrogen atmosphere. The copolymers have a lower thermal decomposition temperature than the polymer-metal complex for the same copolymer composition. The thermal behavior may be correlated with the copolymer composition.