Preparation of poly(vinyl alcohol) grafted with acrylic acid/styrene binary monomers for selective permeation of heavy metals

A study was made to modify water-soluble poly(vinyl alcohol) (PVA) by graft ing acrylic acid and styrene (AAc/Sty) comonomers using gamma rays as an in itiator. The factors that affect the preparation process and grafting yield were studied and more economical grafts under the most favorable reaction conditions were obtained. It was found that the high degree of grafting in such systems was obtained in the presence of an ethanol-water mixture in wh ich water plays a significant role in enhancing the graft copolymerization. The critical amount of water to afford the maximum grafting yield was eval uated. The effect of the comonomer composition on the grafting yield was al so investigated and it was observed that using a mixture of AAc/Sty monomer s influences the extent of grafting of each monomer onto the PVA substrate and the phenomenon of synergism occurs during such a reaction. Also, the de gree of grafting increases as the content of the solvent decreases in the r eaction medium. However, the grafting yield increased as the total dose inc reased. The graft copolymer was characterized by IR and UV spectroscopic me thods. The permeation of heavy metals such as Ni and Co through the grafted membranes was investigated and the efficiency of the separation process wa s also determined. (C) 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 80 6-815, 1999.