Efficiently enriching zinc(II) from and into ammonium chloride media with species regulation and Aliquat336

Solvent extraction of zinc(II) from and into ammoniacal chloride media with trialkylmethylammonium chloride (Aliquat336) has been investigated in the presence and absence of trioctylphospine oxide (TOPO). The results indicate that zinc extraction with Aliquat336 is sensitive to pH and ammonia concentration of ammoniacal chloride solutions. The extraction efficiency of zinc increases with increasing chloride concentration due to the formation of ZnCl3- species. Meanwhile, zinc can be effectively stripped with ammoniacal solutions from the loaded organic phases because of the formation of Zn(NH3)(4)(2+) species. The Aliquat336 mixed with TOPO can induce a synergistic effect on zinc extraction but antagonistic effect on ammonia stripping of zinc. Therefore, through adjusting the coordination equilibrium of zinc species in extraction and stripping processes, the efficient enrichment of zinc ions from and into the ammoniacal chloride media can be achieved by solvent extraction, which is beneficial for zinc recovery from the complex ore resources.