Separation of transition metals and chelated complexes in wastewaters

This review responds to the ongoing needs of wastewater engineers tasked with treating aqueous solutions containing chelated complexes of metal ions, of which nickel citrate in electrodeless plating and copper-EDTA in electronic chip board manufacturing are two key examples. Because of the presence of these sequestering agents, metallic ions cannot be readily precipitated by alkalinity, making a compelling case for the discovery of alternative methods of treatment. This review is a critical appraisal of the varying degrees of success in separation process strategies deployed for the recovery of metallic ions under such challenging chemical conditions. Guidance is provided on making progress toward satisfactory industrial solutions to surmount these difficulties. (c) 2014 American Institute of Chemical Engineers Environ Prog, 34: 761-783, 2015