Uptake of metal ions from aqueous sulphuric acid by resins

The uptake capacity towards heavy metal ions in aqueous sulphuric acid of fourteen crosslinked polymer resins has been studied. Some resins contain poly(amido-amine)s or poly(amido-aminoacid)s crosslinked with 1,4-diaminobutane, others contain free NH2 or oxime groups on a tightly crosslinked structure. All the resins are highly swellable in sulphuric acid solution and, except for the resin containing oxime groups, degrade in a 7-20 days period. All the resins show capacity of retention for Ni2+ in 1.53 M sulphuric acid. The resins of the first group also show some selectivity towards several metal ions in this order: Fe3+ {reversed tilde equals} Zn2+ > Ni2+ > Cu2+. The resin containing oxime as a donor group does not show such a selectivity, but does exhibit larger retention capacity. N.m.r. spectra indicate the presence of ion pairs in H2SO4 solution containing metal ions as M(HSO4)x - n n, vis. negative species, which are retained from the positively charged resins. For the resin containing oxime groups, the retention seems to occur via a coordination mechanism. © 1987.