SELECTIVE RECOVERY OF MERCURY(II) FROM INDUSTRIAL WASTEWATERS .2. ANION-EXCHANGE OF HG(II) CHLOROCOMPLEXES

Strong-base and weak-base anion exchangers are able to remove mercury( II) selectively from chloride-containing solutions at pH 1.5. Leakages are lower from the strong base resin IRA900 than from the weakly basi c IRA93, but at initial Hg concentrations of 10-40 mg/l mercury leakag e from both is below 20 mug/l over at least several hundred bed volume s. Conventional regenerants are ineffective, but Hg(II) is readily des orbed by complexing agents. Desorption reaches 100% in 5 bed volumes o f 1.5 M aqueous 1,2-diaminoethane or about 15 bed volumes of 1 M sodiu m sulfite solution. In some cases the desorbed Hg(II) complex crystall izes from the regeneration effluent. allowing the regenerant to be rec ycled. Chemical or electrolytic reduction of the recovered Hg(II) yiel ds valuable byproduct Hg(I) or Hg(0).