MODIFIED POLYACRYLONITRILE FOR ADSORPTION APPLICATIONS

Polyacrylonitrile (PAN) was produced by redox polymerization of acrylo nitrile and then was modified with 50% aqueous solutions of H2SO4 or N aOH. Copolymers of acrylonitrile' with acrylic acid, acrylamide or met hylenebisacrylamide were prepared by radical polymerization. The struc tures of these polymers based on PAN were studied by IR-spectroscopy i n order to determine their characteristic groups. The cation exchange capacity is higher in polymers containing more acidic groups (COOH), a nd for the examined cases the adsorbability was Cu2+ > Zn2+ (ion excha nge selectivity). The discoloring ability of the examined polymers was studied with aqueous solutions of three dyes, i.e. methylene blue (ca tionic or basic dye), congo red (direct dye having similarities with a nionic dyes) and alizarin yellow (acid dye or anionic monoazo dye). Th e results are interpreted in terms of electron donor-acceptor (EDA) in teractions between the main groups of the polymers and the dyes. The p resence of -CONH2 (having polar character) in the polymers based on PA N, produces favorable interactions with the groups (electron donor or acceptor) of the molecules of the three dyes. The design of new polyme r materials based on PAN with increased adsorption ability, could be p erformed with such a discoloring investigation, especially for methyle ne blue and alizarin yellow.