PMID- 30113817
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20180910
LR  - 20180910
IS  - 1520-510X (Electronic)
IS  - 0020-1669 (Linking)
VI  - 57
IP  - 17
DP  - 2018 Sep 4
TI  - An EPR Investigation of Binding Environments by N-Donor Chelating Exchange Resins 
      for Cu Extraction from Aqueous Media.
PG  - 10857-10866
LID - 10.1021/acs.inorgchem.8b01519 [doi]
AB  - Chelating exchange resins (CERs) are now widely used for metal extraction in 
      aqueous acidic media. Many of these CERs contain surface N-donor ligands, such as 
      di(2-picolylamine) (BPA) and picolylamine (PA), which are highly selective for 
      Cu(II) uptake. Two such widely used resins are Dowex M4195 and CuWRAM. 
      Surprisingly, very little is known about the Cu(II) binding environments on the 
      exchange resins, particularly at variable concentrations and pH's, and therefore 
      we used EPR spectroscopy to investigate this binding. The broad EPR spectra of 
      the Cu(II) loaded resins are quite complex, indicating the presence of multiple 
      Cu(II) binding environments. By preparing a series of well-defined [Cu(II)(PA) 
      (x)] and [Cu(II)(BPA) (x)] complexes and studying their EPR and UV-vis spectra, 
      the individual Cu(II) species contributing to the broad and overlapping EPR 
      spectra of the loaded resins were identified. For Dowex M4195, 
      [Cu(II)(BPA)](H(2)O) (m) and [Cu(II)(BPA)(2)] complexes are most dominant, 
      whereas for CuWRAM two dominant species including [Cu(II)(PA)(2)](H(2)O) (m) and 
      [Cu(II)(PA)(3)] were identified. Notably, [Cu(II)(PA)](H(2)O) (m) was not present 
      in this sample. The experimental spin Hamiltonian parameters for all these 
      species were in good agreement with the density functional theory derived values. 
      Additional intermolecular Cu(II) species were identified on both resins, labeled 
      [Cu(II)(BPA) (x)(BPA) (y)(H(2)O) (n)] and [Cu(II)(PA) (x)(PA) (y)(H(2)O) (n)]. 
      The presence of coordinated water in these intermolecular anchored sites was 
      confirmed in a series of dehydration-rehydration experiments. Furthermore, a 
      series of acid elution experiments also confirmed that these species are less 
      strongly coordinated to the resins compared to the intramolecular species 
      [Cu(II)(BPA)](H(2)O) (m), [Cu(II)(BPA)(2)], [Cu(II)(PA)(2)](H(2)O) (m), and 
      [Cu(II)(PA)(3)]. Finally, while equilibrium batch uptake measurements revealed 
      that the CuWRAM material had a much lower Cu(II) capacity compared to the 
      polymeric Dowex material, the adsorbed copper can be recovered more efficiently 
      using acid elution.
FAU - Spencer, Jacob
AU  - Spencer J
AD  - School of Chemistry , Cardiff University , Park Place , Cardiff CF10 3AT , United 
      Kingdom.
FAU - Stevens, James
AU  - Stevens J
AD  - Johnson Matthey Technology Center , Blounts Court Road , Sonning Common, Reading 
      RG4 9NH , United Kingdom.
FAU - Perry, Christopher
AU  - Perry C
AD  - Johnson Matthey , Building 22, CSIR, Meiring Naude Road , Brummeria 0184 , 
      Pretoria , South Africa.
FAU - Murphy, Damien M
AU  - Murphy DM
AUID- ORCID: 0000-0002-5941-4879
AD  - School of Chemistry , Cardiff University , Park Place , Cardiff CF10 3AT , United 
      Kingdom.
LA  - eng
PT  - Journal Article
DEP - 20180816
PL  - United States
TA  - Inorg Chem
JT  - Inorganic chemistry
JID - 0366543
EDAT- 2018/08/17 06:00
MHDA- 2018/08/17 06:01
CRDT- 2018/08/17 06:00
PHST- 2018/08/17 06:00 [pubmed]
PHST- 2018/08/17 06:01 [medline]
PHST- 2018/08/17 06:00 [entrez]
AID - 10.1021/acs.inorgchem.8b01519 [doi]
PST - ppublish
SO  - Inorg Chem. 2018 Sep 4;57(17):10857-10866. doi: 10.1021/acs.inorgchem.8b01519. 
      Epub 2018 Aug 16.