Stainless steel microbeads coated with sulfonated polystyrene-co-divinylbenzene

A new kind of gel-type magnetic cation-exchange resin based on stainless steel microspheres coated with sulfonated polystyrene-co-divinylbenzene has been synthesized in a two-step process. First, magnetic polymeric beads were prepared by radical suspension polymerization, after which these particles were functionalized by a post-polymerization sulfonation process. The effects of slight modifications in the synthesis process (metal surface modification, initial contact between metal and catalyst, and the use of double polymerization) on the thickness of the polymeric layer were evaluated. Both the precursor magnetic polymeric beads and the final cation exchange resins were studied by scanning electron microscopy and X-ray energy dispersive (EDX) analysis. Finally, the cation exchange capacity of the resins was determined.