Ligand Separation with a Copper(II)-Loaded Polymeric Ligand Exchanger

Abstract

The present study characterizes a new polymeric ligand exchanger (PLE) for enhanced separation of trace anionic ligands, and investigates related interfacial chemistry. Compared to conventional anion exchangers, the PLE exhibited significantly different selectivity sequence and elution profiles, which may be utilized in enhancing selective capture of target solutes and/or chromatographic separation of anionic ligands. Experimental data indicate that the exchanger phase pH is significantly higher across the resin-solution interface caused by the Donnan coion exclusion effect. Intraparticle diffusion appears to be the rate-limiting step during a typical fixed-bed column run. A linear free-energy relationship (LFER) was derived and experimentally validated between the binary separation factors and the aqueous phase metal-ligand stability constants.

Physical–Chemical Processes for Phosphorus Removal and Recovery

“…From a thermodynamic viewpoint, the contribution of DG 0 EL in eqn [21] may be viewed as comparable for both IRA-958 and DOW 3N-Cu. However, the DG 0 SP term is practically zero for IRA-958, but highly negative for DOW 3N-Cu (Zhao and SenGupta, 2000).…”

“…For PLEs, intraparticle diffusion is more likely the rate-limiting step (Zhao, 1997;Zhao andSenGupta, 1998, 2000;An et al, 2005). In a prior study on phosphate sorption, Zhao and SenGupta (2000) identified that intraparticle diffusion is the rate-limiting step during sorption of phosphate to DOW 3N-Cu.…”

“…The solution was given by Crank (1975) and Zhao and SenGupta (2000) as the fractional attainment of equilibrium (F):…”

“…Phosphate can exist in different ionic species such as monovalent H 2 PO À 4 , divalent HPO 2À 4 , and trivalent PO 3À 4 ions, depending on the pH of the solution (pK 1 ¼ 2.1, pK 2 ¼ 7.2, and pK 3 ¼12.3). In most cases, the sorption of anions like phosphate decreases at an elevated pH (e.g., pH 49) (Huang et al, 2008;Zhao and SenGupta, 2000). The pH effect can be attributed to two factors: (1) When the solution pH exceeds the point of zero charge (PZC), the surface of the adsorbents turns negative, and thus, would repulse the negatively charged phosphate species in the solution and (2) the competition of hydroxyl anions becomes more fierce at an elevated pH (e.g., 49 for PLE) (Zhao and SenGupta, 2000).…”

Removal of chelated copper from wastewaters by Fe2+-based replacement–precipitation

“…In response to this challenge and the increasingly stringent environmental regulations, many new treatment methods have been investigated (Fu et al 2007;Korshin et al 2007;Zhao and SenGupta 2000;Ureña-Nuñez et al 2007). Among these methods, replacement-precipitation process is the most economic and effective way.…”