Synergistic extraction of zinc from ammoniacal/ammonia sulfate solution by a mixture of β-diketone and 2-hydroxy-5-nonylacetophenone oxime

Abstract

The solvent extraction of zinc from ammoniacal/ammonium sulfate solutions using a mixture of β-diketone, 1-benzoyl-2 nonyl ketone (Mextral54-100, HA), and 2-hydroxy-5-nonylacetophenone oxime (Mextral 84H, HR) in sulphonated kerosene has been investigated. The effects of different ratio of extractants, extractants concentration, aqueous pH, total ammonia concentration and temperature on zinc extraction were examined. The results indicate that the mixture of Mextral54-100 and Mextral 84H shows evident synergistic effects on zinc extraction, and zinc is extracted as ZnAR by the mixed extractants. As the molar fraction of HR rises, the co-extraction ammonia content increases constantly and reaches a maximum value at χ(HR) 0.5. The extraction efficiency decreases dramatically with the increase of aqueous pH and total ammonia concentration, indicating that the formation of zinc amine complexes depresses the ligand exchange reaction. The thermodynamic parameter ΔH shows that the extractions of zinc by both extraction systems are exothermic driven. FT-IR studies confirm that the ammonia molecules can be co-extracted into synergistic adducts.