Polymer-supported pendant urea groups have been demonstrated to be very efficient in selective removal of mercuric ions from aqueous solutions. Methyl methacrylate (0.5 mol)-glycidyl methacrylate (0.4 mol)-divinylbenzene (0.1 mol) terpolymer beads have been prepared by suspension polymerisation. Urea functions have been incorporated into the bead polymer (210-420 mum) via a two-step modification of the epoxy groups involving firstly reaction with excess of triethylenetetramine followed by acidic isocyanate. The resulting polymer resin has a urea group loading of 7.8 mmol g(-1) and shows excellent mercury binding capacity > 6.7 mmol g(-1), even in the presence of excess chloride ions. The mercury sorption is strictly selective and Ca(II), Mg(II), Zn(H), Pb(II), Fe(II) and Cd(II) ions (0.2-0.3 M) do not give rise to any interference. The mercury can be recovered from loaded beads using hot acetic acid thereby regenerating the polymer. Recovered samples can be recycled more than 20 times without loss of activity as a result of the hydrolytic stability of the urea group in acetic acid.
- selective mercury removal
- polymer supported urea